NEET2020PhysicsElectromagnetic InductionActual
A wheel with 20 metallic spokes each 1   m long is rotated with a speed of 120   rpm in a plane perpendicular to a magnetic field of 0 . 4   G . The induced emf between the axle and rim of the wheel will be, 1   G = 10 - 4   T
Options
- A2 . 51 × 10 - 4   V
- B2 . 51 × 10 - 5   V
- C4 . 0 × 10 - 5   V
- D2 . 51   V
Correct answer
A. 2 . 51 × 10 - 4   V
Step-by-step solution
Given, the angular velocity, ω = 2 π 60 × 120   rad   s - 1 . Recall the formula of induced EMF in terms of angular velocity and radius of the ring, ε = 1 2 B ω r 2 , now put the proper values at proper places, ⇒ ε = 1 2 × 0 . 4 × 10 - 4 × 2 π 120 60 ( 1 ) 2 ⇒ ε = 0 . 8 π × 10 - 4 = 2 . 512 × 10 - 4   V .