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Alternating Current question

2023 · 30 Jan · Shift 2 · Q62
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Alternating Current question

2023 · 30 Jan · Shift 2 · Q62

JEE MainPhysicsAlternating CurrentNumerical+4 / −1
In an ac generator, a rectangular coil of 100 turns each having area 14×10−2 m214 \times 10^{-2} \mathrm{~m}^{2}14×10−2 m2 is rotated at 360 rev/min360 ~\mathrm{rev} / \mathrm{min}360 rev/min about an axis perpendicular to a uniform magnetic field of magnitude 3.0 T3.0 \mathrm{~T}3.0 T. The maximum value of the emf produced will be ‾V\underline{\hspace{2cm}}V​V. (\left(\right.( Take π=227)\left.\pi=\frac{22}{7}\right)π=722​)
Numerical answer
View written solutionFree

Correct answer: 1584

  1. Given data
  • Number of turns: N=100N = 100N=100
  • Area of each turn: A=14×10−2 m2=0.14 m2A = 14 \times 10^{-2} \, \text{m}^2 = 0.14 \, \text{m}^2A=14×10−2m2=0.14m2
  • Magnetic field: B=3.0 TB = 3.0 \, \text{T}B=3.0T
  • Rotation speed: 360 rev/min360 \, \text{rev/min}360rev/min

We need the maximum emf induced in the rotating coil.

  1. Formula for maximum emf in an AC generator

For a coil rotating in a uniform magnetic field,

Emax⁡=NBAωE_{\max} = N B A \omegaEmax​=NBAω

where ω\omegaω is the angular speed.

  1. Convert rotational speed to angular speed

Given:

360 rev/min=36060=6 rev/s360 \, \text{rev/min} = \frac{360}{60} = 6 \, \text{rev/s}360rev/min=60360​=6rev/s

Now,

ω=2πf=2π×6=12π rad/s\omega = 2\pi f = 2\pi \times 6 = 12\pi \text{ rad/s}ω=2πf=2π×6=12π rad/s

Using π=227\pi = \frac{22}{7}π=722​,

ω=12×227=2647 rad/s\omega = 12 \times \frac{22}{7} = \frac{264}{7} \text{ rad/s}ω=12×722​=7264​ rad/s

  1. Substitute into the formula

Emax⁡=NBAωE_{\max} = N B A \omegaEmax​=NBAω

Emax⁡=100×3.0×0.14×2647E_{\max} = 100 \times 3.0 \times 0.14 \times \frac{264}{7}Emax​=100×3.0×0.14×7264​

First simplify:

3.0×0.14=0.423.0 \times 0.14 = 0.423.0×0.14=0.42

So,

Emax⁡=100×0.42×2647E_{\max} = 100 \times 0.42 \times \frac{264}{7}Emax​=100×0.42×7264​

100×0.42=42100 \times 0.42 = 42100×0.42=42

Thus,

Emax⁡=42×2647E_{\max} = 42 \times \frac{264}{7}Emax​=42×7264​

427=6\frac{42}{7} = 6742​=6

Emax⁡=6×264=1584 VE_{\max} = 6 \times 264 = 1584 \, \text{V}Emax​=6×264=1584V

  1. Final answer

1584\boxed{1584}1584​

  1. Comparison with stored correct answer

Stored correct answer = 158415841584

My derived answer matches it exactly.

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