Question

A coil and a bulb are connected in series with a $12$ volt direct current source. A soft iron core is now inserted in the coil. Then

• A. The intensity of the bulb remains the same
• B. The intensity of the bulb decreases
• C. The intensity of the bulb increases
• D. Nothing can be said

Answer 1

Answer: (A)

Intensity of bulb remains the same because source is $DC$, so steady state current will be independent of the inductance of the inductor for $DC$ circuit,
$i_{\text{steady }}=\frac{E_{\text{source }}}{R_{\text{bulb }}}$