Question

A permanent magnet creates a magnetic field at the origin with strength Bperm-1T. A current-carrying wire is oriented such that it creates a magnetic field at the origin that points in the same direction as the magnetic field from the permanent magnet. (a) What is the net magnetic field at the origin if the wire carries a magnitude of 1-2 A and is located a distance r = 5 cm from the origin? (b) If the current in the wire reverses directions, what is the new net magnetic field at the origin?

Answer 1

Answer:

Part a)

$B_{net} = (1 + 4 \times 10^{-6})T$

Part b)

$B_{net} = (1 - 4 \times 10^{-6})T$

Explanation:

Part a)

Since the two magnetic field is in same direction

so the net magnetic field is algebraic sum of magnetic field due to both

so here magnetic field of wire is given as

$B = \frac{\mu_0 i}{2\pi r}$

here we know that

I = 2 A

r = 5 cm

so we will have

$B = \frac{2 \times 10^{-7} (2)}{0.05}$

$B = 4 \times 10^{-6} T$

So net magnetic field is given as

$B_{net} = (1 + 4 \times 10^{-6})T$

Part b)

When direction of current is reversed then the direction of magnetic field is also reversed

So we will have

$B_{net} = (1 - 4 \times 10^{-6})T$