A circular loop of radius 7 cm is placed in uniform magnetic field of 0.2 T directed perpendicular to plane of loop. The loop is converted into a square loop in 0.5 s. The EMF induced in the loop is ____ mV. [2026]

Question

A circular loop of radius 7 cm is placed in uniform magnetic field of 0.2 T directed perpendicular to plane of loop. The loop is converted into a square loop in 0.5 s. The EMF induced in the loop is ____ mV. [2026]

Smart Achievers · Accepted Answer

(2)

$induced EMF = \frac{d ϕ}{d t}$

$circumference ≃ 14 π$

$side length of square loop = \frac{14 π}{4} = \frac{7 π}{2}$

$Δ ϕ = B (A_{1} - A_{2})$

$= (0.2) [(\frac{7 π}{2}) \times \frac{7 π}{2} - 49 π] \times 10^{- 4}$

$= 0.2 (\frac{49 π^{2}}{4} - 49 π) \times 10^{- 4}$

$Δ ϕ = 0.2 \times 33.07 \times 10^{- 4}$

$Δ ϕ = 6.614 \times 10^{- 4}$

$EMF = \frac{6.614 \times 10^{- 4}}{\frac{1}{2}} V = 13.23 \times 10^{- 4} V$

$EMF = 1.32 mV$

Solution

Q.
A circular loop of radius 7 cm is placed in uniform magnetic field of 0.2 T directed perpendicular to plane of loop. The loop is converted into a square loop in 0.5 s. The EMF induced in the loop is ____ mV. [2026]

1 13.2

2 1.32

3 8.25

4 6.6

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