JEE Main20211 Sep 2021Evening ShiftPhysicsElectromagnetic InductionActual
A square loop of side 20 cm and resistance 1 Ω is moved towards right with a constant speed v 0 . The right arm of the loop is in a uniform magnetic field of 5 T . The field is perpendicular to the plane of the loop and is going into it. The loop is connected to a network of resistors each of value 4 Ω . What should be the value of v 0 so that a steady current of 2 mA flows in the loop ?
Options
- A10 - 2   cm   s - 1
- B1   m   s - 1
- C1   cm   s - 1
- D10 2   m   s - 1
Correct answer
C. 1   cm   s - 1
Step-by-step solution
The EMF is induced in the coil when it is moving in a uniform magnetic field, e = B v l and the current, i = e R ⇒ B l v R = 0 . 002   A   ⇒ v = 0 . 002 × R B l = 0 . 002 × 4 + 1 5 × 0 . 2 = 0 . 01   m   s - 1 = 1   cm   s - 1 .