Question 1

The free space inside a current carrying toroid is filled with a material of susceptibility 2 10^ -2 . The percentage increase in the value of magnetic field inside the toroid will be

Accepted Answer

Given, Susceptibility of material, _m=2 10^ -2 Using _ r =1+ _ m =1+0.02=1.02 B _ final = _ r B _0 (here, B _0= initial magnetic field) \% increase in magnetic field = B _ final - B _0 ~B _0 100= _ r B _0- B _0 100 ~B _0 = ( +1)-1 100 1 =0.02 100=2 \%

Question 2

If the B-H curves of two samples of X and Y of iron are as shown below, then which one of the following statement is correct?

Accepted Answer

For permanent magnet we prefer a material with high retentivity and high coercivity. For electromagnet, we prefer high saturated magnetism, low coercivity and least possible area of hystersis loop. Therefore, X is suitable for making permanent magnet and Y for making electromagnet.

Question 3

The angle of dip at a place is 37^ and the vertical component of the earth's magnetic field is 6 10^ -5 ~T . The earth's magnetic field at this place is ( 37^ = 3 4 )

Accepted Answer

= V H = 3 4 [ 37^ = 3 4 ] V = 3 4 H V =6 10^ -5 ~T H = 4 3 6 10^ -5 ~T =8 10^ -5 ~T B _ total = V ^ 2 + H ^ 2 = (36+64) 10^ -5 =10 10^ -5 =10^ -4 ~T .

Magnetic Properties of Matter — Previous Year Questions & Solutions