In a moving coil galvanometer, the coil having 500 turns and an average area of 4 cm2 carries a current of 0.1 A and is set parallel to a magnetic field with a torque of 0.15 N m . The strength of the magnetic field is

Question

In a moving coil galvanometer, the coil having 500 turns and an average area of 4 cm2 carries a current of 0.1 A and is set parallel to a magnetic field with a torque of 0.15 N m . The strength of the magnetic field is (A)  1 T  (B)  5T  (C)  7.5 T  (D)  50 T

Tardigrade Admin · Accepted Answer

Here, N=500, A=4 cm2 =4×10-4m2 I=0.1 A, τ=0.15 N m As torque, τ=NIAB ∴ B=(τ/NIA) =(0.15 Nm/(500)(0.1A)(4×10-4m2)) =7.5 T

Q. In a moving coil galvanometer, the coil having $500$ turns and an average area of $4 c m^{2}$ carries a current of $0.1 A$ and is set parallel to a magnetic field with a torque of $0.15 N m$ . The strength of the magnetic field is

$1 T$

$5 T$

$7.5 T$

$50 T$

Here,
$N = 500, A = 4 c m^{2}$
$= 4 \times 1 0^{- 4} m^{2}$
$I = 0.1 A$ ,
$τ = 0.15 N m$
As torque, $τ = N I A B$
$∴ B = \frac{τ}{N I A}$
$= \frac{0.15 N m}{( 500 ) ( 0.1 A ) ( 4 \times 1 0 ^{- 4} m ^{2} )}$
$= 7.5 T$

Q. In a moving coil galvanometer, the coil having 500 turns and an average area of 4cm2 carries a current of 0.1A and is set parallel to a magnetic field with a torque of 0.15Nm . The strength of the magnetic field is

1T

5T

7.5T

50T