Quiz
Unit 202 Revision: Electrical Science Question Bank 1
Questions in this quiz (40)
1Electric current is described as a flow of
- Aprotons
- Bneutrons
- Celectrons
- Dnucleus
- Aprotons
2Which one of the following identifies the sources of an electromotive force?
- AAtomic, magnetic, thermal
- BChemical, atomic, thermal
- CChemical, magnetic, thermal
- DChemical, magnetic, atomic
3When the current passing through a conductor is increased, the conductor’s temperature will:
- Adecrease
- Bstabilise
- Cfragment
- Dincrease
4The SI unit Henry is used for
- Acapacitance
- Binductance
- Cfrequency
- Dflux density
5Ohm is the SI unit of measurement for:
- Aresistance
- Bvoltage
- Ccurrent
- Dcharge
6The SI unit for frequency is the
- AJoule
- BMole
- CFarad
- DHertz
7Resistance, potential difference and electrical current are expressed in the same order as units of:
- AOhms, Volts, Amperes
- BOhms, Watts, Amperes
- COhms, Volts, Watts
- DWatts, Volts, Ohms
8Transpose the formula Z² = R² + X² to make R² the subject.
- AR² = X² – Z²
- BR² = Z² – X²
- CR² = Z² + X²
- DR² = X² x Z²
9If the resistivity of aluminium is 2.65 x 10 -8 /metre, the resistance of a 65 metre length of 16mm2 aluminium conductor is:
- A10.77Ω
- B1.108Ω
- C0.0108Ω
- D0.108Ω
10For the circuit shown, the total resistance is:
- A108Ω
- B36Ω
- C12Ω
- D3.6Ω
11For the circuit shown, the power dissipated by the 15Ω resistor is:
- A240W
- B60W
- C160W
- D40W
12The power dissipated in the circuit shown on the right would be:
- A35W
- B833W
- C350W
- D1,399W
13When measuring current flow in a d.c. circuit, an ammeter must be connected:
- Ausing a rectifier
- Busing a VT
- Cin series with the load
- Din parallel with the load
14Instrument B in the figure on the right measures the:
- Avoltage drop caused by R2
- Bvoltage drop caused by R3
- Ccurrent through R1
- Dcurrent through R2
15The strength of the magnetic flux produced when current flows in a conductor can be increased by:
- Aincreasing the current
- Bdecreasing the current
- Creversing the current
- Dusing alternating current
16Which one of the following shows the correct poles of the electromagnet when current flows in the direction shown?
- Aa)
- Bb)
- Cc)
- Dd)
17What would be the effect on magnetic flux for the two equal, current-carrying conductors shown?
- AThe magnetic field would halve in strength, flowing in opposite directions
- BThe magnetic fields around each of the conductors would rotate independently
- CThe magnetic fields around the conductors would cancel each other out
- DThe magnetic field around the conductors would double in strength and flow in the same direction
18A conductor of a simple alternator is 0.4m long and cuts a magnetic field with a magnetic flux density of 1.5 tesla at a velocity of 30m/s. The EMF induced in the conductor will be:
- A1,800V
- B180V
- C18V
- D1.8V
19Which one of the following is the supply frequency if a sine wave has a periodic time of 20 milliseconds?
- A40Hz
- B50Hz
- C60Hz
- D70Hz
20Refer to the figure shown. What does value A indicate?
- AAverage value of the waveform
- BPeriodic time of the waveform
- CRMS value of the waveform
- DPeak amplitude of the waveform
21Which one of the following quantities can be described as a force?
- AGravity
- BCurrent
- CResistance
- DEnergy
22The formula shown is used to determine the force required given mass and acceleration. Which one of the following would be the acceleration for a mass of 20kg having a force of 10N applied? F = m x a
- A200 m/s²
- B0.5 m/s²
- C5 m/s²
- D50 m/s²
23The power required to raise a mass of 8kg across a distance of 10m in 40 seconds is approximately:
- A785W
- B80W
- C20W
- D5W
24A motor produces an output of 1.2kW when the input is 1.4kW; its efficiency is:
- A85.7%
- B75.7%
- C65.7%
- D55.7%
25When used to ‘inch’ heavy equipment across the floor, a crowbar is being:
- Aa pulley
- Ba lift
- Ca machine
- Da lever
26Which one of the following instruments would be used to measure the line voltage for the star connected load?
- AA
- BB
- CC
- DD
27In a four-wire, three phase system the phase voltage is 220v. The line voltage will be:
- A380V
- B400V
- C415V
- D420V
28Which one of the following is the phase voltage for a star connected load if the line voltage is 400V?
- A400V
- B230V
- C110V
- D50V
29Which one of the following instruments would be used to measure the line current for the delta connected load?
- AA
- BB
- CC
- DD
30The line current feeding a delta load is 52A. The delta phase current will be:
- A30A
- B52A
- C90A
- D156A
- A30A
31The phase current in a delta load is 10A. The line current will be:
- A5A
- B5.8A
- C10A
- D17.3A
- A5A
32A balanced three phase star connected load draws a line current of 24A per phase. Which of the following is the approximate value of neutral current?
- A0A
- B8A
- C13.9A
- D24A
- A0A
33A d.c. motor in which the current remains constant in the field winding but varies in the armature winding is called:
- Aa compound machine
- Ban armature machine
- Ca shunt machine
- Da series machine
34If a single loop of wire connected to a commutator is rotated in a permanent magnetic field, the voltage measured at the commutator will be:
- Ad.c.
- Ba.c.
- Cintermittent
- Dunidirectional
- Ad.c.
35The diagram shows a simple motor, indicating the field poles and direction of current flow. In which one of the following directions would the conductor move?
- ADirection A
- BDirection B
- CDirection C
- DDirection D
- ADirection A
36In a 400v to 4,000v step-up transformer the ratio of primary to secondary turns ratio will be:
- A10:1
- B5:1
- C1:5
- D1:10
- A10:1
37Which one of the following components would cause current and voltage to behave as indicated in the sine wave shown?
- ARectifier
- BCapacitor
- CInductor
- DResistor
- ARectifier
38The power triangle shown gives the relationship between powers in an a.c. circuit. Which one of the following is the unit used to measure Apparent power?
- AkW
- BkVA
- CkVAr
- DkJ
- AkW
39A circuit dissipates 3kW at a power factor of 0.7 when connected to a 230V a.c. supply. The current flowing in the circuit will be:
- A13.0A
- B18.6A
- C21.5A
- D25.2A
- A13.0A
40Power factor correction in circuits having lagging power factors can be achieved by connecting:
- Ainductors across the load
- Bresistors across the load
- Cresistors in series with the load
- Dcapacitors across the load
- Ainductors across the load
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- C&G 2365 Unit 202 Smartscreen Sample Qs
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- Oliver Balay
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