Basic Electrician Theory MCQ In English ||09||

1. When current flows through the heater coil it glows but the supply wiring does not glow because

(A) Current flows slowly through the supply line

(B) Supply wires are covered with insulation layer

(C) The resistance of the heater wire is greater than the supply wires

(D) Supply wires are made of superior material

Answer: (C)

2. The condition for validity under Ohm's law is that

(A) resistance should be uniform

(B) should be proportional to the size of current resistance

(C) Resistance should be wire wound type

(D) Temperature at positive end should be higher than temperature at negative end

Answer: (A)

3. A rheostat differs from a potentiometer in that it

(A) wattage is low

(B) has high wattage rating

(C) There are a large number of rotations

(D) provides a large number of tapping

Ans: (B)

4. Aluminum conductors weigh more than copper conductors of the same cross-section for the same electrical resistance

(A) 50%

(B) 60%

(C) 100%

(D) 150%

Answer: (A)

5. An open resistor is tested with an ohm-meter. What will be the reading of the ohm-meter?

(A) zero

(B) infinite

(C) high but within tolerance

(D) low but not zero

Ans: (B)

6. They are materials that are much lower in electrical conductivity than most metals, but much higher than typical insulators.

(A) Varistors

(B) thermistor

(C) semiconductor

(D) variable resistor

Answer: (C)

7. All good conductors have high

(A) conduction

(B) resistance

(C) reluctance

(D) thermal conductivity

Answer: (A)

8. Voltage dependent resistors are usually made

(A) Charcoal

(B) silicon carbide

(C) nichrome

(D) graphite

Answer: (C)

9. Voltage dependent resistors are used

(A) for inductive circuits

(B) to suppress surges

(C) as heating elements

(D) as current stabilizers

Ans: (B)

10. The ratio of mass of electron to proton is approx.

(A) 1840

(B) 184

(C) 30

(D) 4

Answer: (A)

11. The number of electrons in the outer most orbit of a carbon atom is

(A) 3

(B) 4

(C) 6

(D) 7

Ans: (B)

12. With three resistors connected in parallel, the total power supplied by the voltage source becomes equal if each consumes 20 W.

(A) 10 W

(B) 20 W

(C) 40 W

(D) 60 W

Answer: (D)

13. A thermistor is

(A) positive temperature coefficient

(B) negative temperature coefficient

(C) zero temperature coefficient

(D) variable temperature coefficient

Answer: (C)

14. If I, R and t are current, resistance and time respectively, then the ratio of heat produced according to Joule's law will be

(A) I²Rt

(B) I²Rf

(C) I²R²t

(D) I²R²t *

Answer: (A)

15. Nichrome wire is of an alloy

(A) lead and zinc

(B) Chromium and Vanadium

(C) Nickel and Chromium

(D) copper and silver

Answer: (C)

16. When a voltage of one volt is applied, a circuit allows a micro ampere current to flow. The conductance of the circuit is

(A) 1 n-mho

(B) 10⁶ mho

(C) 1 milli-mho

(D) None of the above

Answer: (A)

17. Which of the following can have a negative temperature coefficient?

(A) Silver compounds

(B) liquid metals

(C) Metallic alloys Metallic alloys

(D) electrolytes

Answer: (D)

18. conduction: mho ::

(A) resistance: ohm

(B) capacitance: henry

(C) inductance: farad

(D) lumen: steradian

Answer: (A)

19. 1 angstrom is equal to

(A) 10^-8 mm

(B) 10^-6 cm

(C) 10^-10 m

(D) 10^~14 m

Answer: (C)

20. A Newton meter is similar to

(A) one watt

(B) a joule

(C) five joules

(D) one joule second

Ans: (B)