In a balanced Wheatstone bridge, across the centre of the bridge there is.

current and voltage at maximum.

no voltage present at either end

A parallel circuit with any number of 2 terminal connections.

the individual voltage drops is equal to the emf.

has the same current throughout.

the resistance is dependent on current

To find the internal resistance of a battery in a circuit of known current.

find the lost volts of the circuit.

In a series circuit with 3 resistors, the current is.

the total of all 3 using ohms law to find the current.

A load that is subject to a potential difference with a current running through it will.

dissipate power in the form of heat.

have a magnetic field around it with the magnitude and direction of the field determined by the corkscrew rule.

will move in a direction shown by the right hand rule.

The resistance of a material is.

the reciprocal of its conductance

independent of the material type.

The electron flow through a conductor will be decreased the most if the cross sectional area.

is decreased and the length is increased.

and the length are both decreased.

and the length are both increased

Small resistors too small or mis-shapen for the application of colour are marked instead using.

an abbreviated resistance value.

If the resistance of a resistor which is in series with two other resistors is doubled.

the volts drop across that resistor increases.

the current in that resistance is doubled.

the current in that resistance is halved.

In general, increasing the cross sectional area of an electrical cable.

enables it to carry more current.

enables it to carry more voltage.

The formula for resistance in series is.

1/RT = 1/( R1 * R2 * R3 .....Rn).

The resistance to electrical flow in a wire depends on.

the diameter, length, material of wire and temperature.

the material only - copper or aluminium.

the length and material of the wire only.

When resistors are in parallel the total current is equal to.

the current through one resistor.

the reciprocal of all the currents.

Which of these will cause the resistance of a conductor to decrease?.

Decrease the length or increase the cross-sectional area

Decrease the length or the cross-sectional area.

Increase the length or decrease the cross-sectional area.

In a parallel circuit containing resistors.

the voltage is the same in all parts of the circuit.

the sum of the voltage drops equals applied voltage.

resistance is determined by value of current flow.

A 47 Kilohm resistor with a 10% tolerance has the following colour code:.

Yellow, Violet, Orange, Silver.

Quiz

Física 2

oriol arrufat 200 questions

Take the quiz

Questions in this quiz (200)

1The source voltage in the circuit shown is.
1. A200V.
2. B50V.
3. C150V.
2Referring to the drawing, if the volts dropped across the 20 ohm resistor is 10 volts, the resistance of R1 is.
1. A2 ohms.
2. B16 ohms.
3. C20 ohms.
3The current in the circuit shown is.
1. A5 mA.
2. B0.2 A.
3. C5 A
4In the following circuit, the input at P is 4 amps and at Q is 5 amps. What is the voltage across the 6 ohm resistor?.
1. A54V.
2. B6V.
3. C1.5V.
5The unknown current in the network below is.
1. A22A.
2. B3A.
3. C47A
6In a balanced Wheatstone bridge, across the centre of the bridge there is.
1. Acurrent and voltage at maximum.
2. Bno current flow.
3. Cno voltage present at either end
7A 24V battery has an internal resistance of 1 ohm. When connected to a load, 12 amps flows. The value of the load is.
1. A12 ohms.
2. B1/2 ohm.
3. C1 ohm
8A parallel circuit with any number of 2 terminal connections.
1. Athe individual voltage drops is equal to the emf.
2. Bhas the same current throughout.
3. Cthe resistance is dependent on current
9The diagram shows a 200V long shunt generator. What is the voltage across the series resistor.
1. A10V.
2. B6V.
3. C30V.
10To find the internal resistance of a battery in a circuit of known current.
1. Ause the formula R = V * I.
2. Bfind the lost volts of the circuit.
3. Cfind the emf of the circuit.

11For the diagram shown find the voltage at point B.
1. A7V.
2. B26V.
3. C10V.
12In a series circuit with 3 resistors, the current is.
1. Alower than the smallest.
2. Bthe total of all 3 using ohms law to find the current.
3. Ceven in all 3.
13What is the voltage dropped across resistor 'A'?.
1. A2 V.
2. B20 V.
3. C10 V.
14What is the current through resistor C?.
1. A4.5A.
2. B18A.
3. C9A.
15Which is not thermally operated?.
1. AA limiting resistor.
2. BA current limiter.
3. CA fuse
16In a Desynn indicator system, the rotor is.
1. Aan electromagnet.
2. Ba permanent magnet.
3. Can AC magnet.
17A load that is subject to a potential difference with a current running through it will.
1. Ahave a magnetic field around it with the magnitude and direction of the field determined by the corkscrew rule.
2. Bdissipate power in the form of heat.
3. Cwill move in a direction shown by the right hand rule.
18The resistance of a material is.
1. Aindependent of the material type.
2. Bthe same as its conductance.
3. Cthe reciprocal of its conductance
19Resistance is measured using what unit of temperature?.
1. AAbsolute.
2. BCentigrade.
3. CFahrenheit.
20A resistor has 4 bands on it coloured blue, yellow, yellow, gold. It’s value is.
1. A640 kΩ ± 5%.
2. B6.4 mΩ ± 10%.
3. C64 kΩ ± 5%.
21The electron flow through a conductor will be decreased the most if the cross sectional area.
1. Ais decreased and the length is increased.
2. Band the length are both decreased.
3. Cand the length are both increased
22Small resistors too small or mis-shapen for the application of colour are marked instead using.
1. Aan abbreviated resistance value.
2. Ba letter code.
3. Ca dot code
23Total resistance in a parallel resistor circuit, of R1 and R2 is.
1. ART = 1/R1 + 1/R2.
2. B1/RT = (R1 * R2) ÷ (R1 + R2).
3. C1/RT = 1/R1 + 1/R2.
24If the resistance of a resistor which is in series with two other resistors is doubled.
1. Athe current in that resistance is doubled.
2. Bthe volts drop across that resistor increases.
3. Cthe current in that resistance is halved.
25The total resistance of the circuit shown is.
1. A3 Ohms.
2. B1.33 Ohms.
3. C12 Ohms
26Potentiometers are used as a.
1. Avariable voltage source.
2. Bvariable resistor.
3. Cvariable current source.
27 In a Wheatstone Bridge, the ammeter reads zero, and the variable resistor is adjusted to 5 ohms. Resistor P has a value of 10 ohms and Q has a value of 100 ohms. What is the value of the unknown resistor?.
1. A5 ohms.
2. B0.5 ohms.
3. C50 ohms
28In general, increasing the cross sectional area of an electrical cable.
1. Aincreases its resistance.
2. Benables it to carry more voltage.
3. Cenables it to carry more current.
29Six resistors each of 6 ohms would be.
1. A1 ohm in series.
2. B1 ohm in parallel.
3. C36 ohms in parallel.
30A potentiometer varies.
1. Aresistance.
2. Bcurrent.
3. Cvoltage
31The formula for resistance in series is.
1. ART = R1 + R2 + R3 .....Rn.
2. BRT = R1 * R2 * R3 .....Rn.
3. C1/RT = 1/( R1 * R2 * R3 .....Rn).
32What is the combined value of resistances of 4 ohm and 6 ohm connected in parallel?.
1. A0.24 ohm.
2. B2.4 ohm.
3. C24 ohm.
33If a number of resistors are connected in parallel, the total resistance is.
1. Asmaller than the lowest.
2. Bthe same as the lowest.
3. Cgreater than the lowest.
34The resistance to electrical flow in a wire depends on.
1. Athe diameter, length, material of wire and temperature.
2. Bthe material only - copper or aluminium.
3. Cthe length and material of the wire only.
35When resistors are in parallel the total current is equal to.
1. Athe current through one resistor.
2. Bthe sum of the currents.
3. Cthe reciprocal of all the currents.
36Which of these will cause the resistance of a conductor to decrease?.
1. ADecrease the length or the cross-sectional area.
2. BIncrease the length or decrease the cross-sectional area.
3. CDecrease the length or increase the cross-sectional area
37 If 2 resistors, one red, yellow, black, gold and the other violet, blue, black, silver were replaced by a single resistor. Ignoring tolerance, what would the colour coding be?.
1. ABrown, black, brown.
2. BBlack, brown, black.
3. CBrown, black, black.
38A 47 kilohm resistor has the following colour code:.
1. AYellow, Violet, Orange.
2. BRed, Orange, Yellow.
3. COrange, Violet, Red.
39The bridge circuit shown will be balanced when the value of the unknown resistor R is.
1. A2 ohms.
2. B18 ohms.
3. C14 ohms.
40A 300 ohm resistor would have a colour code of.
1. Aorange, brown, black.
2. Borange, orange, brown.
3. Corange, black brown
41In this circuit, Rx is equal to.
1. AR2 * R4 ÷ R3.
2. BR3 * R4 ÷ R2.
3. CR3 * R2 ÷ R4.
42In a parallel circuit containing resistors.
1. Athe sum of the voltage drops equals applied voltage.
2. Bthe voltage is the same in all parts of the circuit.
3. Cresistance is determined by value of current flow.
43Five different value resistors all have the same voltage dropped across them. How are the resistors connected?.
1. AIn Series/Parallel.
2. BIn Series.
3. CIn Parallel
44Conductance of a circuit is 2 milliMhos. What is its resistance?.
1. A5000 Ohms.
2. B500 Ohms.
3. C5 Megohms.
45When light hits a photodiode, its resistance.
1. Astays the same.
2. Bincreases.
3. Cdecreases
46 A 2 Megohm resistor can be written.
1. A2M0F.
2. B20MF.
3. CM20F
47In a Wheatstone bridge at balance the galvanometer reads zero.
1. Aamps.
2. Bohms.
3. Cvolts.
48The unit for resistivity is the.
1. Aohms/square meter.
2. Bohms/meter.
3. Cohm.meter.
49A 47 Kilohm resistor with a 10% tolerance has the following colour code:.
1. AYellow, Violet, Orange, Silver.
2. BOrange, Violet, Red, Gold.
3. CRed, Orange, Yellow, Silver.
50The total resistance in a circuit is greater than the least resistor. This is true for a.
1. Aseries and parallel circuit.
2. Bseries circuit only.
3. Cparallel circuit only.
51The unknown resistance R in the Wheatstone bridge shown is.
1. A4 ohms.
2. B16 ohms.
3. C1 ohm
52This is a symbol for.
1. Aa visual display rectifier.
2. Ba variable differential resistor.
3. Ca voltage dependant resistor
53A potentiometer has which of the following properties?.
1. AWire wound.
2. B3 terminals.
3. CPreset values
54An increase in operating temperature in most electrical devices carrying current results in.
1. Aa decrease in resistance and an increase in current.
2. Bno effect on the resistance and current.
3. Can increase in resistance and a decrease in current
55Copper is an inferior conductor to aluminium when comparing.
1. ACSA with CSA.
2. Bweight for weight.
3. Cload for load.
56What happens to the resistance of a copper conductor when the temperature increases?.
1. AIt decreases.
2. BIt increases.
3. CIt remains the same.
57Carbon has a.
1. Atemperature coefficient of zero.
2. Bpositive temperature coefficient.
3. Cnegative temperature coefficient.
58The 5th coloured band on a resistor represents the.
1. Areliability or temperature coefficient.
2. Btolerance.
3. Cmultiplier.
59If the temperature of a pure metal is reduced to absolute zero, its resistance will be.
1. Aunaffected.
2. Bpractically zero.
3. Cinfinity.
60What is represented by this diagram?.
1. AThermistor.
2. BRheostat.
3. CPotentiometer.
61If a resistor is too small or misshapen to fit the colour code bands, how else is it's value indicated?.
1. ADots.
2. BNumber code.
3. CLetter code.
62This is a diagram of a.
1. ALight Dependant Resistor.
2. BLaser Diode Rectifier.
3. CLogarithmic Differential Resistor.
63This is a diagram of a.
1. AVariable Voltage source.
2. BVariable Current source.
3. CVariable Resistor.
64Resistors required to carry a comparatively high current and dissipate high power are usually of.
1. AWire wound metal type.
2. BCarbon compound type.
3. CWire wound ceramic type.
65A thyristor.
1. Aif energized on, will switch on a circuit.
2. Bhas a positive temperature coefficient.
3. Cif energized on, will switch off a circuit
66The temperature of a pure metal can greatly affect the resistance of it. What temperature scale is used?.
1. AAbsolute.
2. BCentigrade.
3. CFahrenheit.
67A 10 V battery supplies a resistive load of 10 ohms for 1 minute. What is the power supplied?.
1. A100 W.
2. B10 VA.
3. C10 W
68A resistor dissipates 80 Watts. If it runs for 4 hours 15 minutes, how much energy is dissipated in total?.
1. A20.4 kJ.
2. B1.224 MJ.
3. C191.25 J.
69The earth lead of a 24 V equipment is 0.5 ohm resistance and carries 80 A. How much power does it dissipate?.
1. A1.92 kW.
2. B1.152 kW.
3. C3.2 kW.
70What is the power dissipated in a 500 ohm resistor with a 3A flow?.
1. A4.5 kW.
2. B1.5 kW.
3. C750 kW.
71A DC circuit containing a total resistance of 100 ohms has a current flow of 250 mA. The power dissipated in the circuit is.
1. A0.4 watts.
2. B5 watts.
3. C6.25 watts
72Power is the rate of doing work. It is measured in.
1. Ajoules/second.
2. Bjoules * seconds.
3. Cwatts/second
73The power in a circuit when voltage and resistance is given can be found by.
1. AV*R.
2. BV*V*R.
3. CV*V / R
74A 500 ohm resistor carries a 3 amp current. What is the power dissipated?.
1. A500 W.
2. B5 kW.
3. C4.5 kW.
75A 3 ohm resistor dissipates 27 Watts. How much current flows through it?.
1. A9 A.
2. B0.15 A.
3. C3 A.
76A 48-volt source is required to furnish 192 watts to a parallel circuit consisting of three resistors of equal value. What is the value of each resistor?.
1. A4 ohm.
2. B36 ohm.
3. C12 ohm
77A piece of equipment is rated at 750 watts and the applied voltage is 30 volts. The value of the protection fuse should be.
1. A20 amps.
2. B15 amps.
3. C30 amps.
78How much power must a 24-volt generator furnish to a system which contains the following series loads? 5 ohm, 3 ohm and 12 ohm.
1. A402 watts.
2. B28.8 watts.
3. C450 watts.
79A direct current of 12 milliamperes flows through a circuit which has a resistance of 1000 ohms. The power dissipated by the circuit is.
1. A144 milliwatts.
2. B12 watts.
3. C12 milliwatts.
80In the circuit shown, the power developed across the 10 kilo ohm resistor is.
1. A250 mW.
2. B250 W.
3. C50 mW.
81A single phase circuit has an input voltage of 100V. The current is 10A and the circuit has a power factor of 0.5. The true power is.
1. A50W.
2. B1000W.
3. C500W.
82Power in a DC circuit is found by.
1. Amultiplying the voltage by itself and dividing by the current.
2. Bmultiplying current by resistance.
3. Cmultiplying the resistance by the current squared
83If the energy supplied to a circuit for 4hrs 15 minutes at 800 j/sec what would be the energy consumed?.
1. A3400 KW Hrs.
2. B3.4 KW Hrs.
3. C340 KW Hrs.
84A heater which consumes 800 Kilojoules/sec is on for 4hrs 15min. The energy consumed is.
1. A340 kWh.
2. B3.4 kWh.
3. C3400 kWh.
85A voltage of 250V causes a current of 30mA. What is the wattage?.
1. A7.5W.
2. B7500W.
3. C0.225W
86Which requires the most electrical power during operation?.
1. AA 12-volt motor requiring 8 amperes.
2. BFour 30-watt lamps in a 12-volt parallel circuit.
3. CTwo lights requiring 3 amperes each in a 24volt parallel system
87The power dissipated in a circuit with a known potential difference and resistance is calculated by.
1. Amultiplying the square of the potential difference by the resistance.
2. Bdividing the square of the potential difference by the resistance.
3. Cfinding the current and multiplying the answer by the resistance
88The power expended in a given circuit is.
1. Ainversely proportional to cube-root of the current.
2. Bproportional to the square-root of the voltage.
3. Cproportional to the square of the voltage.
89A capacitor is fully charged after 25 seconds to a battery voltage of 20 Volts. The battery is replaced with a short circuit. What will be the voltage across the capacitor after one time constant?.
1. A0 volts.
2. B7.36 volts.
3. C12.64 volts.
90The voltage rating of a capacitor is.
1. Athe max voltage that can be constantly applied.
2. Bthe min voltage required to charge.
3. Cthe normal operating voltage.
91The relative permittivity of a capacitor is.
1. Athe permittivity of the dielectric.
2. Bthe relative permittivity of the dielectric in relation to a vacuum.
3. Cthe permittivity of dielectric in relation to dry air.
92When checking a capacitor with an ohmmeter, if the reading shows charging but the final reading is less than normal then the possible fault is a.
1. Aleaking dielectric capacitor.
2. Bshort circuit dielectric.
3. Copen circuit dielectric.
93Three capacitors 10 microfarads, 10 nanofarads and 10 millifarads are connected in parallel. What is the total capacitance?.
1. A10.01001 millifarads.
2. B111 millifarads.
3. C1.001001 millifarads.
94If a 1milliFarad capacitor has a potential difference across it of 5V, what is the energy stored?.
1. A12.5 Joules.
2. B12.5 milliJoules.
3. C25 mJoules.
95A capacitor with double the area and double the dielectric thickness will have.
1. Adouble the capacitance.
2. Bthe same capacitance.
3. Chalf the capacitance.
96 An electrolytic capacitor is used where.
1. Aminimum losses are essential.
2. Bthere is a polarized input.
3. Chigh frequency AC is used
97What must you do to make a 3 F capacitor circuit into a 2 F circuit?.
1. APut a 2 F capacitor in parallel.
2. BPut a 6 F capacitor in series.
3. CPut a 1 F capacitor in series.
98The time required to fully charge a 1 µ(micro)F capacitor in series with a 100k ohm resistor is.
1. A100 seconds.
2. B100 milliseconds.
3. C500 milliseconds.
99A 50 μ(micro) Farad capacitor is fed with a current of 25 milliAmpere. How long will it take to charge it to 100Volts?.
1. A1 second.
2. B0.2 seconds.
3. C12 minutes.
100In a circuit C = 25 microfarads and the current flow is 40 microamps for 4 seconds. What is the voltage?.
1. A6.4Volts.
2. B3.2Volts.
3. C12.8Volts
101Three 12 µ(micro)F capacitors are in series. The total capacitance is.
1. A12 µ(micro)F.
2. B4 µ(micro)F.
3. C36 µ(micro)F.
102The time constant of a capacitor is the time.
1. Athe current to reach 63.2% of maximum.
2. Bfor the emf to reach 63.2% of maximum.
3. Cto reach maximum current.
103The amount of electricity a capacitor can store is directly proportional to the.
1. Aplate area and inversely proportional to the distance between the plates.
2. Bdistance between the plates and inversely proportional to the plate area.
3. Cplate area and is not affected by the distance between the plates.
104The capacitance of a capacitor is dependant upon.
1. Athe rate of change of current in the circuit.
2. Bthe type of material separating the plates.
3. Cthe charge on it.
105When different rated capacitors are connected in parallel in a circuit, the total capacitance is.
1. Aless than the capacitance of the lowest rated capacitor.
2. Bequal to the capacitance of the highest rated capacitor.
3. Cequal to the sum of all the capacitances.
106One Picofarad is.
1. A1 * 1012 farad.
2. B1 * 10-6 farad.
3. C1 * 10-12 farad.
107The switch on a DC circuit containing a fully charged capacitor is opened. The voltage across the capacitor.
1. Adrops immediately to zero.
2. Bstarts to fall exponentially to zero.
3. Cremains equal to the original charging voltage supply.
108The current in a DC circuit containing a fully charged capacitor is.
1. Azero.
2. Bis dependent upon the size of the capacitance of the capacitor.
3. Cmaximum.
109 A capacitor is a barrier to.
1. Aboth.
2. BA.C.
3. CD.C
110What is the total capacitance of a parallel circuit containing three capacitors with capacitance of 0.25microfarad, 0.03microfarad, and 0.12microfarad, respectively?.
1. A0.4 µ(micro)F.
2. B0.04 µ(micro)F.
3. C0.04 piko Farad.
111When two capacitors are connected in series.
1. Athe charge stored on each is inversely proportional to the voltage across it.
2. Bthe charge stored on each is the same.
3. Cthe charge stored on each is directly proportional to its capacitance
112The charge on a capacitor is expressed as.
1. Athe ratio Q/V.
2. Bthe product Q * V.
3. Cthe product C * V.
113When handling a high voltage capacitor in an electrical circuit, be sure it.
1. Ahas a full charge before removing it from the circuit.
2. Bis fully discharged before removing it from the circuit.
3. Chas at least a residual charge before removing it from the circuit
114The dielectric constant of a capacitor is a measurement of.
1. Athe electrical resistance of the capacitor dielectric.
2. Bthe electrostatic energy storing capacity of the capacitor dielectric.
3. Cthe electrical repulsion of electrons within the dielectric material
115Three 12 microfarad capacitors in parallel. The overall circuit capacitance is.
1. A4 microfarads.
2. B1 microfarads.
3. C36 microfarads.
116A circuit has 1 megohm and 8 microfarads. What is the time constant?.
1. A8 seconds.
2. B1 second.
3. C40 seconds.
117 A capacitor rating is.
1. Athe voltage it will charge to.
2. Bthe maximum continuous voltage it can take.
3. Cthe voltage it will rupture at
118The multiplier colour coding on a capacitor is in.
1. Apicofarads.
2. Bfarads.
3. Cmicrofarads.
119The total capacitance of the circuit shown is.
1. A36µ(micro)F.
2. B4µ(micro)F.
3. C3µ(micro)F.
120When a capacitor is charged from a DC supply, the voltage/time curve is.
1. Alogarithmic.
2. Blinear.
3. Cexponential.
121An electrolytic capacitor is used because it has a.
1. Asmall physical size for low leakage current.
2. Blarge physical size for a large capacity.
3. Csmall physical size for a large capacity
122An electrolytic capacitor would be used in circuits supplying.
1. Aheavy loads.
2. Blight loads.
3. Cheavy / light loads.
123A 20 Picofarad capacitor with a 1 Megohm resistor takes how long to charge?.
1. A100 microseconds.
2. B20 milliseconds.
3. C0.1 second.
124The discharge curve of a capacitor is.
1. AExponential.
2. BLogarithmic.
3. CLinear
125What is the value of a monolithic capacitor with 103 on it?.
1. A1000pf.
2. B10,000pf.
3. C100,000pf.
126What is the formula for working out the capacitance of a capacitor if K = dielectric constant, A = area of the plates, d = distance plates apart?.
1. Ac = K*A/d.
2. Bc = d/K*A.
3. Cc = K*d/A.
127Total capacitance of 3 capacitors each 12milliFarad in a parallel circuit.
1. A36milliFarad.
2. B12milliFarad.
3. C6mf.
128A combination of 1 megohm and 8 microfarad would give a time constant of.
1. A40 seconds.
2. B400 ms.
3. C8 seconds
129Generally, what is the voltage across a fully charged capacitor?.
1. ALess than circuit voltage.
2. BSame as circuit voltage.
3. CMore than circuit voltage.
130 When would you use an electrolytic capacitor?.
1. AOn a balanced circuit.
2. BLow output compared to size required.
3. CLarge output compared to size required
131 A capacitor has Brown, Black and Orange bands. It's value is.
1. A10 picofarads.
2. B10 nanofarads.
3. C100 picofarads.
132Voltage measured between the plates of a capacitor will be generally.
1. Acan dangerously higher than applied voltage.
2. Bthe same as applied voltage.
3. Cless than applied voltage.
133Dielectric constant of a capacitor is.
1. Amax V that can be applied to a capacitor.
2. Belectrostatic storing capability of the dielectric.
3. Cmax I stored in the capacitor
134One microfarad is.
1. A1 * 10-12 farads.
2. B1 * 1012 farads.
3. C1 * 10-6 farads.
135A circuit with a capacitor has 6 volts applied to it with a charge of 2400 pico-coulombs. What would the charge be if the applied voltage was 1.5 volts ?.
1. A2400 * 10-12 coulombs.
2. B600 * 10-9 coulombs.
3. C600 * 10-12 coulombs
136 In a capacitor, the dielectric strength is measured in.
1. AFarads per meter.
2. BVolts per metre.
3. CCoulombs per m2.
137Three capacitors connected in series, each having a value of 12 picofarads, calculate the total capacitance.
1. A36 picofarads.
2. B4 picofarads.
3. C12 picofarads.
138Magnetic inclination is the least at the.
1. Apoles.
2. Bequator.
3. Cisoclines
139Ferromagnetic materials can be magnetized.
1. Abelow a certain temperature.
2. Babove a certain temperature.
3. Cwithin a band of temperatures.
140Glass is an example of a.
1. Acoercive material.
2. Bparamagnetic material.
3. Cdiamagnetic material
141 A solenoid of 10 turns per metre carries a current of 5A. If the current is reduced to 2.5A, how many turns would be required to maintain the same magnetic field?.
1. A20.
2. B50.
3. C5.
142Which of the following materials is easiest to magnetize?.
1. AHigh grade steel.
2. BSoft iron.
3. CCast iron
143To find which end of an electromagnet is the north pole, use the.
1. AFleming's Left Hand Rule.
2. BRight Hand Clasp Rule.
3. CCork Screw Rule.
144The earth's magnetic field is greatest at the.
1. Amagnetic equator.
2. Bgeographic poles.
3. Cmagnetic poles
145The lines of magnetic flux from a magnet will.
1. Aattract each other.
2. Brepel each other.
3. Chave no effect upon each other
146Of the following which pair of materials would most readily become magnetized?.
1. AIron and steel.
2. BCopper and steel.
3. CNickel and bronze.
147The core material used for an electromagnet is soft iron because.
1. Aits magnetism is not easily destroyed.
2. Bit retains most of its flux density when demagnetized.
3. Cit demagnetizes easily.
148If the North pole of a magnet is brought nearer to the North pole of another magnet.
1. Aattraction between them will be increased.
2. Brepulsion between them will be reduced.
3. Crepulsion between them will be increased.
149Where is the magnetic dip least?.
1. APoles.
2. BIsoclinals.
3. CEquator.
150When a number of ferrite pieces are grouped together, they.
1. Aare semi-permanent magnets when DC is passed through them.
2. Belectromagnets.
3. Ccan be used to store binary code.
151Ampere turns is calculated by the number of turns.
1. Amultiplied by current.
2. Bdivided by current.
3. Cmultiplied by magnetic flux
152The unit of flux is the.
1. AAmpere turns / metre.
2. BWeber.
3. CAmpere turns
153Lines of magnetic flux pass from.
1. ASouth to North.
2. BEast to West.
3. CNorth to South.
154Why is ferrite used in memory circuits?.
1. AHigh reluctance.
2. BLow permeability.
3. CHigh remanence.
155Magnetic lines are flowing parallel. They will.
1. Ahave no effect on each other.
2. Battract each other.
3. Crepel each other
156The horizontal component of the earth's magnetic field is most strongly felt at.
1. Aequator.
2. B45 degrees latitude.
3. Cpoles.
157Two parallel lines of magnetic flux in the same polarity.
1. Arepel each other.
2. Bhave no effect on each other.
3. Cattract each other.
158Magnetic fields around two parallel conductors carrying current in the same directions will.
1. Arepel.
2. Battract.
3. Cwill attract or repel depending on the type of current.
159Magnetic field on a solenoid is.
1. Athe same both inside and outside the coil.
2. Bweakest outside the coil.
3. Cstrongest outside the coil.
160Which of the following is absolute permeability?.
1. Aµ(micro)r.
2. Bµo(micro node).
3. Cµ(micro
161 A paramagnetic material has a relative permeability of.
1. Azero.
2. Bless than unity.
3. Cgreater than unity.
162Through which material will magnetic lines of force pass the most readily?.
1. ACopper.
2. BIron.
3. CAluminium.
163Permanent magnets have.
1. Ahigh reluctance, high coercive force.
2. Blow reluctance, high coercive force.
3. Chigh reluctance, low coercive force
164The term used to denote the strength of a magnetic field is.
1. Aretentivity.
2. Bhysteresis.
3. Cflux density
165 A soft iron core is used in an ELECTRO magnet because.
1. Ait has LOW permeability and HIGH coercivity.
2. Bit has HIGH permeability and LOW coercivity.
3. Cit has HIGH permeability and HIGH coercivity.
166A non-magnetic metal.
1. Ahas high retentivity.
2. Bhas no permeability.
3. Cis a poor conductor.
167What is the effect of inserting an iron core into a current carrying coil?.
1. AThe flux density of the original magnetic field remains constant.
2. BThe core tends to move from a stronger to a weaker part of the field.
3. CThe flux density of the original magnetic field produced by the coil is increased
168Flux density will.
1. Aincrease linearly with coercive force.
2. Bdecrease linearly with magnetic flux.
3. Cincrease linearly with magnetic flux
169Storage of magnets should be.
1. Ain a non magnetic pox.
2. Bin pairs with keeper plates.
3. Cin pairs end to end
170The hysteresis loop for a magnetic material is on a graph with.
1. Acurrent against flux density.
2. Bflux density against magnetising force.
3. Ctotal flux against flux density.
171A material with a narrow hysteresis loop.
1. Acannot be magnetised.
2. Bwill have high retentivity.
3. Cwill have low retentivity
172If a bar magnet is cut in half.
1. Athe magnet is destroyed.
2. Btwo bar magnets are formed.
3. Cone bar magnet and one non-magnet is formed
173Copper is a.
1. Aferromagnetic material.
2. Bparamagnetic materials.
3. Cdiamagnetic material
174The MMF of a coil fed with 2 amps and having 10 turns is.
1. A5 ampere turns.
2. B20 amperes / turn.
3. C20 ampere turns.
175An example of a paramagnetic material is.
1. Asilver.
2. Biron.
3. Cglass
176Vibration in a magnet causes.
1. Aflux to stay the same.
2. Bflux to decrease.
3. Cflux to increase
177Permeability of a material can be found by.
1. Aflux density / MMF.
2. BMMF * flux density.
3. CMMF / flux density.
178When magnetizing a piece of material, magnetic strength will rise.
1. Anon-linearly with magnetic force.
2. Blinearly with coercive force.
3. Clinearly with magnetic force
179A material exposed to heat will.
1. Ahave no effect on magnetism.
2. Bbe easier to magnetise.
3. Cbe harder to magnetise.
180If cobalt has a permeability of 4800 it is a.
1. Aferromagnetic.
2. Bparamagnetic.
3. Cdiamagnetic.
181Cobalt has a permeability.
1. Agreater than unity.
2. Bless than unity.
3. Csame as unity.
182Magnetic flux.
1. Aexist in all space around the magnet.
2. Bis more concentrated at the centre of bar magnet.
3. Coccupies the space around the magnet with equal flux density.
183The ability of a circuit to produce a magnetic flux under the influence of a MMF.
1. Apermeance.
2. Bpermeability.
3. Cpermanence
184Magnetic flux saturation takes place when.
1. Athe magnetised medium will accept no further lines of flux.
2. Bthe magnetic field drops to zero.
3. Cthe magnetic field starts to reduce with increased magnetising force
185Cables are shielded to prevent 'H' magnetic interference in wires with the following material.
1. ACopper braiding.
2. BFerromagnetic material.
3. CDiamagnetic material
186Spontaneous magnetism is associated with.
1. Adiamagnetic materials.
2. Bferromagnetic materials.
3. Cparamagnetic materials
187Two inductive coils are placed in close proximity with each other at 90 degrees. The number of flux linkages is.
1. A0.
2. Bmaximum negative.
3. Cmaximum positive.
188What is the mutual inductance if two coils of 10mH and 500mH have 90% of the flux transferred from one to the other?.
1. A459mH.
2. B4.5mH.
3. C63mH.
189An inductor has 1,000 turns of wire and a cross sectional area of 0.001m2. If the core has a permeability of 0.000,001 and the coil is 0.1m. What is the value of the inductor?.
1. A100microH.
2. B100mH.
3. C10mH
190Three inductors 10 mH, 5 mH and 20 mH are connected in parallel. What is the total inductance?.
1. AWithout knowing the coupling factor the total inductance cannot be found.
2. B2.86mH.
3. C35mH.
191If the current reaches a maximum through an inductor of 2A in 15 seconds, what is the current after 3 seconds?.
1. A1.26A.
2. B0.63A.
3. C1A.
192The time constant of an inductor is.
1. AL/R.
2. BL2 /R.
3. CLR.
193If the rate of change of current is halved, mutual inductance will.
1. Astay the same.
2. Bhalve.
3. Cdouble.
194Why are the iron cores of most induction coils laminated?.
1. ATo reduce the effects of eddy currents.
2. BTo reduce the core reluctance.
3. CTo increase the core permeability
195When more than two inductors of different inductance are connected in parallel in a circuit, the total inductance is.
1. Aequal to the sum of the individual inductance.
2. Bequal to the inductance of the highest rated inductor.
3. Cless than the inductance of the lowest rated inductor.
196The time constant in an inductive circuit is the time required for the current to reach.
1. A70.7% of maximum value.
2. B63.2% of maximum value.
3. C63.7% of maximum value.
197An AC inductive circuit has an inductance 0f 10 mH and a frequency input of 1000Hz. The opposition to current flow is approximately.
1. A63 ohms.
2. B63,000 ohms.
3. C630 ohms
198Rotating coil B through 90° will.
1. Aincrease the EMF induced into B.
2. Bincrease the EMF induced into A.
3. Cdecrease the EMF induced into B.
199An inductor of resistance 5 kΩ and inductance 2mH is connected to a DC circuit. The time constant is.
1. A400 ns.
2. B10 seconds.
3. C40 ms.
200When switching off the supply, the back EMF in a collapsing field in an inductor.
1. Acan be multiple times bigger than forward EMF.
2. Bnever exceeds forward EMF.
3. Cis equal to forward EMF.

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Description: Quiz on Física 2, created by oriol arrufat on 12/10/2018.
Author: oriol arrufat
Language: English
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