1. A current of 1 A is drawn by a filament of an electric bulb. Number of electrons passing through a cross-section of the filament in 16 seconds would be roughly ?

1023

1018

1020

1016

Answer: 1020

Explanation:

Q = ne and Q = It ? ne = It


2. How many joules of electrical energy are transferred per second by a 6 V; 0.5 A Lamp ?

0.83 J/s

30 J/s

3 J/s

12 J/s

Answer: 3 J/s

Explanation:

Electrical energy transferred per second, E = V x I x t = 6 V × 0.5 A × 1s = 3 J/s


3. The free electrons of a metal ?

Are free to escape through the surface

Do not collide with each other

Are free to move anywhere in the metal

Do not collide with each other

Answer: Are free to move anywhere in the metal

Explanation:


4. The current in a wire ?

Does not depend on resistance and potential difference

Depends only on the resistance of the wire

Depends on both resistance and potential difference

Depends only on the potential difference applied

Answer: Depends on both resistance and potential difference

Explanation:


5. When there is an electric current passing through a wire, the particles moving are ?

Ions

Electrons

Atoms

Protons

Answer: Electrons

Explanation:


6. What is the maximum resistance which can be made using five resistors each of 1/5 W ?

10 ohm

1 ohm

5 ohm

1/5 ohm

Answer: 1 ohm

Explanation:

Series combination provide the maximum resistance.


7. A student carries out an experiment and plots the V-I graph of three samples of nichrome wire with resistances R1 R2 and R3 respectively. Which of the following is true ?

R2 > R3 > R1

R3 > R2 > R1

R1 > R2 > R3

R1 = R2 = R3

Answer: R3 > R2 > R1

Explanation:

Current is inversely proportional to the resistance for the same potential. So higher resistance would allow less current to pass through its which is shown by R3 as I3 < I2 < I1 ? R3 >R2 > R1


8. The resistivity does not change if ?

the temperature is changed

both material and temperature are changed

the material is changed

the shape of the resistor is changed

Answer: the shape of the resistor is changed

Explanation:

The resistivity does not change if the shape of resistor is changed because nature of material will remain same.


9. A cylindrical conductor of length l and uniform area of cross-section A has resistance R. Another conductor of length 2l and resistance R of the same material has area of cross-section ?

2A

3A

3A/2

A/2

Answer: 2A

Explanation:


10. What is the maximum resistance which can be made using five resistors each of 1/5 ohm ?

1 ohm

5 ohm

10 ohm

1/5 ohm

Answer: 1 ohm

Explanation:

The maximum resistance is obtained when resistors are connected in parallel combination. This equivalent resistance will be: Rs = n x R = 5 X 1/5 = 1ohm Rs = equivalent resistance for series combination.