Two identical conducting balls having positive charges q₁ and q₂ are separated by a centre to centre distance r. If they are made to touch each other and then separated to the same distance, the force between them will be _____.

(a)

less than before

(b)

same as before

(c)

more than before

(d)

zero

An electric field \(\vec { E } =10x\hat { i } \) exists in a certain region of space. Then the potential difference V = V_o – V_A, where V_o is the potential at the origin and V_A is the potential at x = 2 m is _____.

(a)

10 V

(b)

-20 V

(c)

+20 V

(d)

-10 V

Two points A and B are maintained at a potential of 7 V and -4 V respectively. The work done in moving 50 electrons from A to B is _______.

(a)

8.80 x 10^-17 J

(b)

-8.80 x 10^-17 J

(c)

4.40 x 10^-17 J

(d)

5.80 x 10^-17 J

A parallel plate capacitor stores a charge Q at a voltage V. Suppose the area of the parallel plate capacitor and the distance between the plates are each doubled then which is the quantity that will change?

(a)

Capacitance

(b)

Charge

(c)

Voltage

(d)

Energy density

Two metallic spheres of radii 1 cm and 3 cm are given charges of -1 \(\times\) 10^-2 C and 5 \(\times\) 10^-2 C respectively. If these are connected by a conducting wire, the final charge on the bigger sphere is

(a)

3 \(\times\) 10^-2 C

(b)

4 \(\times\) 10^-2 C

(c)

1 \(\times\) 10^-2 C

(d)

2 \(\times\) 10^-2 C