Ch 3. Current Electricity

Question 1

The relation between the drift velocity (V d) and applied electric field (E) of a conductor is

Answer 1

V d ∝ E

V d Proportional To E

Question 2

Two resistors R and 2R are connected in series in an electric circuit. The thermal energy developed in R and 2R will be in ratio

Answer 2

1:2

Question 3

The motion of electron inside the conductor is

Answer 3

Drifting

Question 4

What is mainly measured by potentiometer?

Answer 4

Potential Difference

Question 5

One ampere is equal to

Answer 5

1 coulomb/1 second

Question 6

Unit of electromotive force is

Answer 6

Volt

Question 7

Which of the following is correct for resistivity of a material?

Answer 7

P = RA/L

Question 8

The heat produced in a conductor of resistance R due to flow of current I for time t is

Answer 8

I².R.t

Question 9

Value of green colour code on carbon resistance is

Answer 9

5

Question 10

The value of yellow colour in colour code of carbon resistance is

Answer 10

4

Question 11

Which of the following is the best conductor of electricity?

Answer 11

Silver

Question 12

Which of the following is the same in parallel connection of resistances?

Answer 12

Potential difference

Question 13

1 volt is equal to

Answer 13

1JC⁻¹

Question 14

The value of red colour in colour code of carbon resistance is

Answer 14

2

Question 15

At constant potential difference, the resistance of any electric circuit is halved, the value of heat produced will be

Answer 15

Double

Question 16

The current flowing in a wire is 1A. If the charge of an electron is 1.6 × 10¹⁹C, then the number of electrons flowing through the wire per second is

Answer 16

6.25 × 10¹⁸

Question 17

When two bulbs of power 60W and 40W are connected in series, then the power of their combination will be

Answer 17

24W

Question 18

The specific resistance of a conductor increases with

Answer 18

Increase of temperature

Question 19

The drift velocity (Vd) and applied electric field (E) of a conductor are related as :

Answer 19

Vd ∝ E

Question 20

Two cells of e.m.f. ε₁ and ε₂, internal resistance r₁ and r₂, connected in parallel. The equivalent e.m.f. of the combination is

Answer 20

ε₁ r₂ + ε₂ r₁/ r₁ + r₂

Question 21

Which element is used in electric heater?

Answer 21

Nichrome

Question 22

Absorbed electrical energy is

Answer 22

Proportional to the square of the potential difference

Question 23

Dimension of electromotive force (e.m.f.) is

Answer 23

M¹ L² T⁻³ I⁻¹

Question 24

Ampere - hour is unit of

Answer 24

Charge

Question 25

The power of electric circuit is

Answer 25

V²/R

Question 26

A current flows in a wire of resistance 5Ω having potential difference 7 volt for 20 minutes. The heat produced is

Answer 26

2800 cal

Question 27

In the following Question Nos. (1) to (4), there are two columns. Column 1 contains 4 questions. You have to match the correct options of these questions as A, B,C,D from column 2.

Answer 27

Ohm’s law — Potential difference/current = Constant

Kirchhoff’s law — Conservation of energy

Force × Velocity — Potential difference × current

Kilowatt-hour — Potential difference × current × Time

Question 28

A current of 10 ampere flows in a wire for 10 second. If potential difference across the wire is 15 Volt, the work done will be

Answer 28

1500J

Question 29

The electrical resistance of a healthy man is

Answer 29

50,000Ω

Question 30

Kilowatt-hour (kWh) is the unit of

Answer 30

Energy

Question 31

Statement 1 : The electrical lamp light up immediately after switch is on.

Statement 2 : The free electrons of fire move with speed of light.

Answer 31

Statement 1st is true, but Statement 2nd is false.

Question 32

Statement 1 : A large dry cell has higher e.m.f.

Statment 2 : The e.m.f of a dry cell is proportional to its size.

Answer 32

Statement 1st is false, but Statement 2nd is true.

Question 33

Which of the following is correct for current density?

Answer 33

J = I/A

Question 34

Which of the following is correct for mobility?

Answer 34

µ = Vd/E

Question 35

Which of the following is correct?

Answer 35

1 watt = 1 Js⁻¹

Question 36

Colour code of carbon resistance for blue colour is

Answer 36

6

Question 37

Wheatstone’s bridge is used in measuring

Answer 37

Both high and low resistance

Question 38

The algebraic sum of all currents meeting at any point in an electrical circuit is

Answer 38

Zero