• # question_answer If a 30 V, 90 W bulb is to be worked on a 120 V line, a resistance of how many ohms should be connected in series with the bulb [MP PMT 2002; KCET 2003] A)            10 ohm                                    B)            20 ohm C)            30 ohm                                    D)            40 ohm

Suppose resistance R is corrected in series with bulb. Current through the bulb $i=\frac{90}{30}=3\,A$ Hence for resistance $V=i\,R$Þ $90=3\times R\Rightarrow R=30\,\Omega$