Target Exam

CUET

Subject

Physics

Chapter

Electric Charges and Fields

Question:

Read the passage and answer the question.

Two spherical conductors B and C having equal radii and carrying equal charges in them repel each other with a force F, when kept apart at some distance. A third spherical conductor having same radius as that of B but uncharged, is brought in contact with B, then brought in contact with C and finally removed away from both. The new force of repulsion between B and C is:

Following from last question, what is the charge on A?

Options:

3Q/8

3Q/4

3Q/2

Q/2

Correct Answer:

3Q/4

Explanation:

The correct answer is Option 2: 3Q/4

The initial charges on B and C are equal, say Q each.

When the uncharged conductor A touches B, Charge gets equally shared (since radii are same):

B = Q/2, A = Q/2

A now touches C (which has charge Q)

Total charge = Q/2 + Q = 3Q/2

This gets equally divided:

A = 3Q/4, C = 3Q/4

Final charges:

B = Q/2, C = 3Q/4, A = 3Q/4

Thus, the charge on A is 3Q/4.