Question

Two infinitely long wires carrying currents of $5\text{A}$ each are shown in the options. For which of the following figures, the value of magnetic field at point $P(a,a)$ is zero?

• A.
• B.
• C.
• D. None of these

Answer 1

The correct option is A

Using right-hand thumb rule, we can see that, magnetic field at $P$ due to wire $1$ will be inward and due to wire $2$ will be outward.

Also, point $P$ is equidistant from both the wires.
Hence, magnetic field $(B=\frac{{\mu }_{o}I}{2\pi a})$ due to both wires will cancel each other at point $P$ as the same current flows through the wires and the point is equidistant from the wires.

Therefore, net magnetic field will be zero at point $P$.

So, option $a$ is correct.

Why this Question ? This question will help the students to properly recall the application of Right-hand curl rule.