Electromagnetic Induction | Physics JEE Main questions with Solutions

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Topic Question Set

Q 1 :
A rectangular loop of length 2.5 m and width 2 m is placed at 60° to a magnetic field of 4T. The loop is removed from the field in 10 sec. The average emf induced in the loop during this time is [2024]

$- 2 V$
$+ 2 V$
$+ 1 V$
$- 1 V$

1

2

3

4

(C) $e = - \frac{0 - (4 \times (2.5 \times 2) \cos 60 °)}{10} = + 1 V$

Q 2 :
A coil is placed perpendicular to a magnetic field of 5000T. When the field is changed to 3000T in 2s, an induced emf of 22 V is produced in the coil. If the diameter of the coil is 0.02 m, then the number of turns in the coil is [2024]

70
140
35
7

1

2

3

4

(A) $ε = N (\frac{Δ ϕ}{t})$

$Δ ϕ = (Δ B) A$

$B_{i} = 5000 T, B_{f} = 3000 T$

$Δ ϕ = (Δ B) A = (2000) π {(0.01)}^{2} = 0.2 π$

$ε = N (\frac{Δ ϕ}{t}) \Rightarrow 22 = N (\frac{0.2 π}{2})$

$\Rightarrow N = 70$

Q 3 :
The magnetic flux $ϕ$ (in weber) linked with a closed circuit of resistance 8 Ω varies with time (in seconds) as $ϕ = 5 t^{2} - 36 t + 1$ . The induced current in the circuit at t = 2s is _____ A. [2024]

0%

(2) $ε = - (\frac{d ϕ}{d t}) = - 10 t + 36$

$at t = 2 s, ε = 16 V$

$i = \frac{ε}{R} = \frac{16}{8} = 2 A$

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