You have an 1200 W toaster, a 1800 W electric pan, and a 500 W coffee maker. You

Question

You have an 1200 W toaster, a 1800 W electric pan, and a 500 W coffee maker. You have them plugged into the same outlet, so they are all connected in parallel.

(A) What current does each device draw?

(B) If this circuit has a 20 A circuit breaker, what combinations of devices can you run simultaneously?

(C) Suppose you want to make toast and coffee. Suppose the cold (starting) resistance of each device is a factor of 2 less than the hot (running) resistance. Do you have to start the coffee before the toast or vice versa? (Does it matter?)

Explanation / Answer

outelet voltage=120 volts

part a:

votlage across each component=120 volts

as power=voltage*current

current drawn by toaster=1200/120=10 A

current drawn by electric pan=1800/120=15 A

current drawn by coffee maker=500/120=4.1667 A

part B:

we can use toaster and coffee maker at the same.

we can use electric pan and coffee maker at the same time.

part C:

as cold resistance is factor of 2 less than hot resistance, then cold current wil be twice the hot current.

let you start the coffee maker first .

current drawn is within safe limit.

then if you start toaster, coffee maker will be drawing its hot current by then i.e. 4.1667 A

the cold current of the toaster will be 2*10=20 A

so it will cross the limit and hence you cant stat toaster after coffee maker.

now let see the reverse.

if you start the toaster first, it will draw 20 A, within the limit and by the time you switch on the coffee heater, toaster will be drawing only 10 A making it perfectly safe to switch on the coffee maker.

so you should only start the coffee maker after the toaster is up and running.

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.