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NEET PHYSICSELECTROMAGNETIC INDUCTIONEasy

Question

A 800 turn coil of effective area 0.05 m20.05 \text{ m}^2 is kept perpendicular to a magnetic field 5×105 T5 \times 10^{-5} \text{ T}. When the plane of the coil is rotated by 9090^\circ around any of its coplanar axis in 0.1 s0.1 \text{ s}, the emf induced in the coil will be:

A

0.02 V0.02 \text{ V}

B

2 V2 \text{ V}

C

0.2 V0.2 \text{ V}

D

2×103 V2 \times 10^{-3} \text{ V}

Step-by-Step Solution

According to Faraday's Law of Induction, the magnitude of the induced emf (ε\varepsilon) is equal to the rate of change of magnetic flux (ΦB\Phi_B) linked with the coil .

1. Calculate Initial Flux (Φi\Phi_i): The coil is perpendicular to the magnetic field, meaning the angle θ\theta between the area vector and the magnetic field is 00^\circ (or 180180^\circ). Φi=NBAcos(0)=NBA\Phi_i = N B A \cos(0^\circ) = N B A

2. Calculate Final Flux (Φf\Phi_f): The plane of the coil is rotated by 9090^\circ, so the angle between the area vector and the magnetic field becomes 9090^\circ. Φf=NBAcos(90)=0\Phi_f = N B A \cos(90^\circ) = 0

3. Calculate Change in Flux (ΔΦ\Delta \Phi): ΔΦ=ΦfΦi=0NBA=NBA|\Delta \Phi| = |\Phi_f - \Phi_i| = |0 - N B A| = N B A

4. Calculate Induced EMF (ε\varepsilon): ε=ΔΦΔt=NBAΔt|\varepsilon| = \frac{|\Delta \Phi|}{\Delta t} = \frac{N B A}{\Delta t}

Given Values: N=800N = 800 A=0.05 m2A = 0.05 \text{ m}^2 B=5×105 TB = 5 \times 10^{-5} \text{ T} Δt=0.1 s\Delta t = 0.1 \text{ s}

Substitution: ε=800×(5×105)×0.050.1|\varepsilon| = \frac{800 \times (5 \times 10^{-5}) \times 0.05}{0.1} ε=800×25×1070.1|\varepsilon| = \frac{800 \times 25 \times 10^{-7}}{0.1} ε=20000×1070.1|\varepsilon| = \frac{20000 \times 10^{-7}}{0.1} ε=2×1030.1|\varepsilon| = \frac{2 \times 10^{-3}}{0.1} ε=2×102 V=0.02 V|\varepsilon| = 2 \times 10^{-2} \text{ V} = 0.02 \text{ V}

Exam Context & Concepts Covered

This question aligns with the NEET PHYSICS syllabus, specifically targeting concepts from ELECTROMAGNETIC INDUCTION. Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

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