Two bulbs $A$ and $B$ are rated as $90 \, W - 120 \, V$ and $60 \, W - 120 \, V$ respectively. They are connected in parallel across a $120 \, V$ source. Find the current in each bulb. Which bulb will consume more energy?

Vedclass pdf generator app on play store
Vedclass iOS app on app store
(A) $(i)$ For bulb $A$:
Resistance,$R_{A} = \frac{V^{2}}{P_{A}} = \frac{(120)^{2}}{90} = 160 \, \Omega$.
Therefore,current $I_{A} = \frac{V}{R_{A}} = \frac{120}{160} = 0.75 \, A$.
For bulb $B$:
Resistance,$R_{B} = \frac{V^{2}}{P_{B}} = \frac{(120)^{2}}{60} = 240 \, \Omega$.
Therefore,current $I_{B} = \frac{V}{R_{B}} = \frac{120}{240} = 0.5 \, A$.
$(ii)$ Since the bulbs are connected in parallel to a $120 \, V$ source,each bulb operates at its rated voltage. Bulb $A$ has a higher power rating $(90 \, W)$ compared to bulb $B$ $(60 \, W)$,therefore bulb $A$ will consume more energy.

Explore More

Similar Questions

Why is much less heat generated in long electric cables than in filaments of electric bulbs?

$100 \, J$ of heat is produced each second in a $4 \, \Omega$ resistance. Find the potential difference across the resistor. (in $, V$)

When a high resistance voltmeter is connected directly across an electric bulb,its reading is $2 \ V$. An electric cell is sending a current of $0.4 \ A$ (measured by an ammeter) in the electric circuit.
$(a)$ Draw the circuit.
$(b)$ Find the resistance of the electric bulb.
$(c)$ State the law that is applied for making these calculations. If a graph is plotted between $V$ and $I$,show the nature of the graph obtained.

Which solution is used as an electrolyte in a Voltaic cell?

The $V-I$ graphs for two wires $A$ and $B$ are shown in the figure. If we connect both the wires one by one to the same battery, which of the two will produce more heat per unit time? Give justification for your answer.

Difficult
View Solution

Vedclass Products

For Students

Vedclass Test Series

Mock tests in real JEE/NEET style with performance analysis. 5-day free trial.

Start Free Trial
For Teachers

Exam Paper Generator

Generate Set A/B/C/D exam papers from 7.5L+ questions in 2 minutes. 3 chapters free.

Try Free
For Institutes

Online Exam Module

Live online exams with unlimited students, 360° analytics & white-label branding.

See Demo