JEE Advance - Physics (2008 - Paper 2 Offline - No. 13)

STATEMENT 1 : The sensitivity of a moving coil galvanometer is increased by placing a suitable magnetic material as a core inside the coil.

and

STATEMENT 2 : Soft iron has a high magnetic permeability and cannot be easily magnetized or demagnetized.

Statement 1 is True, Statement 2 is True; Statement 2 is a CORRECT explanation for Statement 1

Statement 1 is True, Statement 2 is True; Statement 2 is a NOT CORRECT explanation for Statement 1

Statement 1 is True, Statement 2 is False

Statement 1 is False, Statement 2 is True

Statement 1 is true.

We know that,

Sensitivity $$ = {\theta \over I} = {{NBA} \over C}$$

If we place soft iron in magnetic field it get magnetise so magnetic field increases. Hence, sensitivity of a moving coil will also increase.

Therefore, $$\overrightarrow B $$ the $${\theta \over I}$$ also increases.

When we place any suitable magnetic material inside the core, the magnetic field will increase.

Statement 2 is wrong because soft iron can be easily magnetized and de magnetized.