Question

Out of two bulbs $50W,100W$, which one will glow brighter if $\left(SAT\right)$ Connected in series When connected in parallel

• A. $\left(a\right)50W\left(b\right)100W$
• B. $\left(a\right)100W\left(b\right)100W$
• C. $\left(a\right)100W\left(b\right)50W$
• D. $noneofabove$

Answer 1

The correct option is A $\left(a\right)50W\left(b\right)100W$

For a given rated voltage bulb,

The resistance of 50W rated bulb is much more than that of the 100W bulb.resistance is given by:

$R=\frac{V^2}{P}$

and the total current in the circuit in series is given by:

$I=\frac{V}{R_S}$

where $R_S=R_A+R_B$

as the same current passes through each bulb when connected in series,50W bulb will glow brighter as power, $P=I^{2}R$, is more in case of $50W$bulb.

similarly, when the bulbs are connected in parallel, 100W the bulb will be much brighter as power,$P=\frac{V^2}{R}$, is more in case of $100W$ bulb.