Alight, a heater, and a hair dryer were all running in the bathroom at the same time. suddenly, they all turn off. after all, the light usually stays on just fine whenever you use the bathroom. why would it go off now?

answer this question assuming the circuit breaker or fuse for the bathroom has a 40-ampere capacity. use the terms “circuit,” and “overload.” then think of at least two solutions to prevent this from happening again.

Well depending on what current the heater pulls im going to assume about 13, and 13A for the hair dryer, thats 26A on the 40A circuit.
I dont see how a lightbulb could overload the circuit. 

Anyway, assuming the circuit is overloaded by some really big heater- the circuit would trip, the fuse would go and remain off. Most houses are fitted with seperate circuits for lights and sockets, so the light may remain on depending on the breaker board. - the reason for them all being able to run with the sudden overload may be due to a surge.

One solution to this is not to put such a large heater on the circuit with other appliances. 

Another may be to dry your hair in the dark