Five long wires A, B, C, D and E, each carrying current I are arranged to form edges of a pentagonal prism as shown in figure. Each carries current out of the plane of paper.
(a) What will be magnetic induction at a point on the axis O? Axis is at a distance R from each wire.
(b) What will be the field if current in one of the wires (say A) is switched off?
(c) What if current in one of the wire (say) A is reversed?

Explanation

To solve the given problem, we will analyze the magnetic induction at a point on the axis of a pentagonal prism formed by five long wires carrying current out of the plane of the paper.

### Part (a): Magnetic Induction at Point O

1. **Identify the Contribution from Each Wire**:
Each wire (A, B, C, D, E) contributes to the magnetic field at point O. The magnetic field due to a long straight wire carrying current I at a distance R from the wire is given by the formula:
\[
B = \frac{\mu_0 I}{2 \pi R}
...