Question

A coil of area 50 cm2 has 1000 turns. Magnetic field of 0.2 weber/m2 is perpendicular to the coil. The magnetic field is reduced to zero in 0.2 second. The induced emf in the coil is.

-1 V
-5 V
-10 V
-0 V

Answer 1

Using Faraday's Law, we calculate the induced emf in a coil with 1000 turns and an area of 50 cm2 as the magnetic field changes from 0.2 weber/m2 to 0 in 0.2 seconds, which results in an induced emf of -5 V.The correct option is option b.

Step-by-step explanation:

The question involves calculating the induced electromotive force (emf) in a coil when there is a change in the magnetic field it is exposed to. This is a direct application of Faraday's Law of electromagnetic induction, which states that an emf is induced in a circuit when there is a change in the magnetic flux that the circuit encloses.

To find the induced emf, we use the formula Ε = -N ∆Φ/∆t, where Ε is the induced emf, N is the number of turns in the coil, ∆Φ is the change in magnetic flux, and ∆t is the time over which this change occurs. For a coil with an area A and exposed to a magnetic field B, the magnetic flux Φ is given by Φ = B × A.

In this case, we have a coil with 1000 turns (N = 1000) and an area of 50 cm², which needs to be converted to square meters (A = 50 × 10^-4 m²). The magnetic field changes from 0.2 weber/m² to 0 in 0.2 seconds, so ∆B = 0.2 T and ∆t = 0.2 s. Calculating the change in magnetic flux ∆Φ gives us ∆Φ = 0.2 weber/m² × 50 × 10^-4 m² = 0.001 weber (or 0.001 Wb). Thus, the induced emf Ε is -1000 × 0.001 Wb / 0.2 s = -5 V.

Therefore, the answer is a generated emf of -5 V.