Practice portal › Current Electricity › Electrical Energy and Power

A 6.0 volt battery is connected to two light bulbs as shown in figure. Light bulb 1 has resistance 3 ohm while light bulb 2 has resistance 6 ohm. Battery has negligible internal resistance. Which bulb will glow more? [Figure: bulb 1 and bulb 2 are connected in parallel, each between a common left rail and a common right rail; the 6.0 V battery is connected between the left and right rails, so each bulb gets the full 6 V.]

Asked in JEE Main Online 2012 · Rated bulbs and appliances

• (1) Bulb 1 will glow more first and then its brightness will become less than bulb 2
• (2) Bulb 1
• (3) Bulb 2
• (4) Both glow equally

Step-by-step solution

Why the other options are wrong

• (1) With a steady source and fixed resistances the powers do not swap over time.
• (3) Uses the series rule (power proportional to R), but the bulbs are in parallel.
• (4) Equal brightness would need equal resistances.

Reading this solution needs no sign-in. You only sign in to practise against the clock and keep your progress.