Question

Two small magnets are placed horizontally perpendicular to magnetic meridian. Their north poles are at 30cm east and 20cm west from a compass needle. Compare the magnetic moments of the magnets, if compass needle remains undeflected.

Answer 1

Explanation:

here in this question the needle remains undeflected that means that point the magnetic field is zero .

Now when , the north poles are 30 cm east and 20 cm west from a compass needle then ,

Answer 2

Given:  North poles are at 30 cm east and 20 cm west from a compass needle.

To find: Compare the magnetic moments of the magnets.

Solution:

• Now we have given that there are two small magnets.

• They are placed horizontally perpendicular to magnetic meridian. Their north poles are at 30 cm east and 20 cm west from a compass needle.

• Now we have given a condition that compass needle remains un-deflected.

• This means at that point the magnetic field is zero.

• Now according to the formula:

                      B = μm / 4πl

                      l is the distance.

• So now B1 = B2 = 0.

• So putting the values in formula, we get:

                      μ x m1 / 4π (30)^3 = μ x m2 / 4π (20)^3

• Cancelling similar terms, we get:

                      m1 / 27000 = m2 / 8000

                      m1 / m2 = 27000/8000

                      m1 / m2 = 27/8

                      m1 : m2 = 27 : 8

Answer:

           So the ratio is 27 : 8.