A square wire loop of 10.0 cm side lies at right angles to a uniform magnetic field of 7 T. A 10 V light bulb is in a series with the loop as shown in the figure. The magnetic field is decreasing steadily to zero over a time interval Δ t. For what value of Δ t (in .× 103 sec ), the bulb will shine with full brightness?

Question

A square wire loop of 10.0 cm side lies at right angles to a uniform magnetic field of 7 T. A 10 V light bulb is in a series with the loop as shown in the figure. The magnetic field is decreasing steadily to zero over a time interval Δ t. For what value of Δ t (in .× 103 sec ), the bulb will shine with full brightness? (A)  (B)  (C)  (D)

Tardigrade Admin · Accepted Answer

Induced emf should be equal to 10 V e=A (d B/d t) ⇒ 10=((10/100))2 (7/Δ t) ⇒ Δ t=7 ms

Induced emf should be equal to 10V e=AdtdB​ ⇒10=(10010​)2Δt7​ ⇒Δt=7ms

Induced emf should be equal to $10 V$
$e = A \frac{d B}{d t}$
$\Rightarrow 10 = (\frac{10}{100})^{2} \frac{7}{Δ t}$
$\Rightarrow Δ t = 7 m s$