Question

(i) A 100W and 60W bulb are joined in series and connected to the mains. Which bulb will glow brighter? Why?
(ii) A 100W and 60W bulb are joined in parallel to the mains. Which bulb will glow brighter? Why?

Answer 1

Answer:

Resistance of of 60 Watt bulb is more than 100 Watt as resistance = V^2/Wattage

When these bulb are connected in series than current in both bulb is same, and Watt consumed can be given as i^2 x R, as Resistance of 60 W bulb is more than 100W bulb, so it will consume more power and glow brighter than 100W bulb.

When these bulb are connected in parallel, voltage across both bulb is same and power consumption will be V^2/R. In this case bulb with low resistance will consume more power and glow brighter than the bulb with high resistance, so 100W bulb will glow brighter than 60W bulb.

Explanation:

hope it's helpful

Answer 2

1) 100w is brighter because it dissipates more power

2) 100w is brighter because it has smaller resistance.