A small torch bulb is rated at 4.5 V, 720 mW. Find its working resistance. Calculate the value of the series resistance needed for the bulb to operate normally from a 12 V supply with an internal resistance of 4 ohms
The same bulb operates normally when connected directly across another supply that has an e.m.f. of 6 V.
Calculate the internal resistance of this supply.
I’d really appreciate if someone could share what they get for this question as I don’t have access to the answer! Xx