Test
CURRENT ELECTRICITY
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Preguntas del test (35)
1What are the minimum requirements to cause the flow of current?
- AA voltage source, an ammeter, a conductor and an insulator
- BA voltage source, a switch and a resistor
- CA voltage source and a conductor
- DA voltage source, a conductor and an insulator
2Out of the following, select the best conductor of electricity.
- AGraphite
- BChina Clay
- CPorcelain
- DNone of these
3Which of the following statements is correct?
- AThe resistance does not play an important role in electrical engineering.
- BThe resistance of a wire does not depend upon its material.
- CThe resistance of most of the materials is independent of the temperature.
- DThe resistance of conductor is the hindrance by which the conductor opposes the flow of the current.
4Resistance of a conductor increases when
- Aits length increases
- Bits area increases
- Cboth length and area increases
- Dspecific resistance is kept constant
5The specific resistance ρ depends upon
- AThe area of cross-section and the length of the conductor
- BThe material of the conductor, its area of cress-section and length
- CThe nature of the material of the conductor only
- DThe area of cross-section of the conductor
6The specific resistance ρ is defined as
- Aresistance of a conductor which has a length of 1 m and cross-section of 1 m2 at 20C
- Bresistance of any conductor at 25C
- Cresistance of any conductor at 20C
- Dresistance of a conductor which has a length of 1 m and cross-section of 1 cm2 at 20C
7The resistance of a conductor, when its temperature is increased
- Aremains constant
- Bincreases
- Cvaries
- Ddecreases
8It was experimentally found by James Prescott Joule that the heat produced in a current carrying conductor is proportional to
- Athe square of the current
- Bsquare of resistance
- Cthe current
- Dinversely proportional to time
9The value of Joule's mechanical equivalent of heat, J, is equal to
- A4.2 calories per Joule
- B2.4 Joules per calorie
- C4.2 Joules per calorie
- D4.2 Joules
10Temperature coefficient of a conductor is defined as the
- Aincrease in resistance per ohm per degree centigrade
- Bincrease in resistance per degree centigrade
- Cincrease in resistance per degree absolute
- Ddecrease in resistance per ohm per degree centigrade
11When current flows in a conductor, heat is produced because
- Aheat α I²
- Bof electronic collision
- Cof interatomic collision
- Dof Joule's law
12Heating effect of current has undesirable side effect in
- Aelectric oven
- Belectric iron
- Cimmersion heater
- Dvacuum cleaner
13The resistance of carbon (filament in carbon-filament lamps) when its temperature is decreased
- Aincreases
- Bdecreases
- Cremains the same
- Dincreases enormously
14The curve representing Ohm's law is
- Aa parabola
- Blinear
- Csine function
- Da hyperbola
15The condition in Ohm's law is that
- Aratio V/I should be constant
- Bcurrent should be proportional to voltage
- Cthe temperature should remain constant
- Dthe temperature should vary
16Ohm's law does not apply to
- Aconductors
- Bconductors when there is change in temperature
- Csemiconductor
- Da.c. circuit
17Ohm's law is applicable to
- Aelectric arc
- Brectifying devices
- Cgas discharge lamps
- Dnone of these
18Ohm's law can be applied with certain reservations to
- Arectifying devices
- Bsemiconductors
- Celectrolytes
- Dthermionic valves
19The presence of an electric current is made known by
- Aflashing
- Beffects produced
- Ccracking
- Delectric shock
20An electric current can neither be ____ nor ____.
- Afelt, seen
- Bseen, touched
- Cseen, produced by any effect
- Dproduced, felt
21The presence of the current is only made known by the effect it produces. Three important effects are
- Aheating, electric shock and generation
- Bgeneration, chemical and electric shock
- Cheating, magnetic and electric shock
- Dheating, magnetic and chemical
22Voltage applied across a circuit, acts as
- Amass of electrons
- Bnegative ions
- Ca component of current
- Da force
23In a series circuit the current is
- Aconstant
- Balways zero
- Cproportional to the resistance
- Ddifferent from resistors
24In a parallel circuit the potential difference across the resistance
- Avaries
- Bis different from the applied voltage
- Cis sometimes constant
- Dis always constant
25The resistance R1 and R2 are connected in parallel. The ratio of values of resistance R1 : R2 is 4 : 1. The currents in R1 : R2 will be equal to
- A1 : 4
- B1 : 1
- C4 : 1
- D4 : 4
26A resistance of 4 ohms is connected across 100 V supply. When another resistor 'R' ohms is connected in parallel with 4 ohms, the total current taken from supply was found to be 50 A. The value of resistance 'R' is
- A2 ohms
- B3 ohms
- C5 ohms
- D4 ohms
27The voltage applied across an electric press was reduced by 50%. The power consumed by the press will be reduced by
- A25%
- B75%
- C60%
- D50%
28Two electric presses are connected in parallel. The resistance of the first press is 100 ohms and that of the second is 300 ohms. The total current taken by both the presses is 4 A. The ratio of current taken by first : second will be equal to
- A2 : 3
- B1 : 3
- C3 : 1
- D1.2 : 3
29Three elements having conductance G1. G2 and G3 are connected in parallel. Their combined conductance will be
- AG1 + G2 + G3
- B1/(G1 + G2 + G3)
- C(G1G2 + G2G3 + G3G1)/(G1 + G2 + G3)
- D1/(1/G1 + 1/G2 + 1/G3)
30Four resistance R1, R2, R3 and R4 are connected in series against 220 V supply. The resistances are such that R1 > R2 > R3 > R4. The least power consumption will be in
- Aresistor R1
- Bresistor R4
- Cresistor R3
- Dresistor R2
31When current flows through heater coil it glows but supply wiring does not glow because
- Asupply wiring is covered with insulation layer
- Bcurrent through supply line flows at slower speed
- Csupply wires are made of superior material
- Dresistance of heater coil is more than that of supply wires
32Resistors commonly used in power circuits are
- Acarbon resistors
- Betched circuit resistors
- Cwire wound resistors
- Ddeposited metal resistors
33International ohm is defined in terms of resistance of
- Aa column of mercury
- Ba cube of carbon
- Cunit length of metal wire
- Da cube of copper
34Which of the following has negative coefficient of resistance?
- Awire wound resistor
- Bnon-metals
- Cthermistor
- Dmetals
35The current carrying capability of the fuse material depends on
- Alength
- Bmaterial
- Ccross-sectional area
- Dall of these
Información
- Descripción
- A compilation of objective type questions in Electrical Engineering
- Autor
- Owen Ryan Ang
- Idioma
- English
- Visitas
- 685
- Etiquetas
- Valoración
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