A disc of radius 0.1 m is rotating with a frequency 10 rev / s in a normal magnetic field of strength 0.1 T. Net induced emf is

Question

A disc of radius 0.1 m is rotating with a frequency 10 rev / s in a normal magnetic field of strength 0.1 T. Net induced emf is (A)  2π × 10-2V  (B)  2π2 × 10-2V  (C)  (π /2)× 10-2V  (D) None of these

Tardigrade Admin · Accepted Answer

Given: r =0.1 m v=10 rev / s B =0.1 T Area of disc A =π r 2=π(0.1)2 m 2 Angular frequency W =2 π v=20 π rad / s ∴ Emf induced E = BAw =0.1 × π(0.1)2 × 20 π=2 π2 × 10-2 V

Q. A disc of radius $0.1 m$ is rotating with a frequency $10 re v / s$ in a normal magnetic field of strength $0.1 T$ . Net induced emf is

$2 π \times 1 0^{- 2} V$

$2 π^{2} \times 1 0^{- 2} V$

$\frac{π}{2} \times 1 0^{- 2} V$

None of these

Given : $r = 0.1 m v = 10 re v / s B = 0.1 T$
Area of disc $A = π r^{2} = π (0.1)^{2} m^{2}$
Angular frequency $W = 2 π v = 20 π r a d / s$
$∴$ Emf induced $E = B A w = 0.1 \times π (0.1)^{2} \times 20 π = 2 π^{2} \times 1 0^{- 2} V$

Q. A disc of radius 0.1 m is rotating with a frequency 10rev/s in a normal magnetic field of strength 0.1T. Net induced emf is

2π×10−2V

2π2×10−2V

2π​×10−2V