# Multiple Choice Questions (MCQ) on DC Basics and Network for Electrical Engineering

In this article, we are providing you MCQ on DC Basics and Network for Electrical Engineering.

1 - In gases, the flow of current is due to

(a) electrons only.

(b) positive and negative ions.

(c) electrons and positive ions.

(d) electrons, positive ions, and negative ions.

Ans = d

2. The minimum requirements for causing a flow of current are

(a) a voltage source, a resistor, and a switch.

(b) a voltage source and a conductor.

(c) a power source and a bulb.

(d) a voltage source, a conductor, an ammeter, and a switch.

Ans = b

3. Current velocity through a copper conductor is

(a) nearly 3 x 10^9 m/s.

(b) of the order of a few micro m/s.

(c) independent of current strength.

(d) the same as propagation velocity of electric energy.

Ans = b

4. The drift velocity of electrons is

(a) larger than the speed of light.

(b) almost equal to the speed of light.

(c) equal to the speed of light.

(d) very small in comparison to the speed of light.

Ans = d

5. The condition for the validity of

**Ohm's law**is that the(a) temperature should remain constant.

(b) current should be proportional to voltage.

(c) Resistance should be wire wound type.

(d) all of the above.

Ans = a

6. Two wires A and B of the same material and length l and 2l have radius r and 2r respectively. the ratio of their specific resistance will be

(a)1:1

(b)1:2

(c)1:4

(d)1:8

Ans = a

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7. The electrical conductivity of metals is typical of the order of (In 1/ohm-m)

(a)10^7

(b)10^5

(c)10^-4

(d)10^-6

Ans = a

8. Resistance of a copper wire always increases if

(a) temperature is reduced.

(b) temperature is increased.

(c) the number of free electrons available becomes less.

(d)the number of free electrons available becomes more.

Ans = b/c

9. Pure metals generally have

(a) high conductivity and low-temperature coefficient.

(b) high conductivity and large-temperature coefficient.

(c) low conductivity and zero temperature coefficient.

(d) low conductivity and high-temperature coefficient.

Ans = b

10. The temperature coefficient of resistance of a wire is 0.0008 °C, the resistance of the wire is 8 ohm at 0°C, what is the resistance at 100°C?

(a) 8.64 Ohm.

(b) 8.08 Ohm.

(c) 7.92 Ohm.

(d) 7.20 Ohm.

Ans = a

11. If the length of a wire of resistance R is uniformly stretched to n times its original value, its new resistance is

(a) nR

(b) R/n

(c)n^2R

(d)R/n^2

n^2 = n square

Ans = c

12. The hot resistance of the filament of a bulb is higher than the cold resistance because the temperature coefficient of the filament is

(a) negative

(b) infinite

(c) zero

(d) positive

Ans = d

13. temperature coefficient of resistance of an insulator is

(a) positive and independent of temperature.

(b) negative and independent of temperature.

(c) negative and dependent on temperature.

(d) positive and dependent on temperature.

Ans = c

14. Four resistances 80 ohms,50 ohms,25 ohms, and R ohms are connected in parallel. Current through 25 ohms resistance is 4 A. The total current of the supply is 10 A. The value of R will be

(a) 66.66 ohm

(b) 40.25 ohm

(c) 36.36 ohm

(d) 76.56 ohm

Ans = c

15. Three parallel resistive branches are connected across a dc supply. What will be the ratio of the branch currents I1 :I2: I3, if the branch resistances are in the ratio R1: R2: R3:: 2: 4: 6?

(a) 3:2:6

(b) 2:4:6

(c) 6:3:2

(d) 6:2:4

Ans = c

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