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NEET PHYSICSEasy

The magnetic flux linked with a coil (in Wb) is given by the equation ϕ=5t2+3t+60\phi = 5t^2 + 3t + 60. The magnitude of induced emf in the coil at t=4t = 4 s will be:

A

33 V

B

43 V

C

108 V

D

10 V

Step-by-Step Solution

  1. Faraday's Law: The magnitude of the induced electromotive force (emf) ε\varepsilon in a circuit is equal to the time rate of change of magnetic flux ϕ\phi through the circuit. Mathematically, ε=dϕdt|\varepsilon| = \left| \frac{d\phi}{dt} \right| .
  2. Differentiation: We are given the magnetic flux function ϕ=5t2+3t+60\phi = 5t^2 + 3t + 60. To find the induced emf, we differentiate this function with respect to time tt: dϕdt=ddt(5t2+3t+60)=10t+3\frac{d\phi}{dt} = \frac{d}{dt}(5t^2 + 3t + 60) = 10t + 3.
  3. Calculation: We need to find the magnitude of the induced emf at t=4t = 4 seconds. Substituting t=4t = 4 into the derivative: ε=10(4)+3|\varepsilon| = 10(4) + 3 ε=40+3=43 V|\varepsilon| = 40 + 3 = 43 \text{ V}.
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