Jim and Jenny just moved into a rental house. Early Sunday morning, Jim decides

Question

Jim and Jenny just moved into a rental house. Early Sunday morning, Jim decides to surprise Jenny and cook breakfast for her. He starts cooking bacon in the electric frying pan (1000-watt) while he perks the coffee (600-watt). Jim decides to make some toast (700-watt) while he waits for the bacon and coffee to finish cooking. Just before he starts the toaster, Jim notices that the kitchen circuit is protected by a 20 amp fuse. He looks around and can't find any spare fuses. Should Jim start the toast now, or wait until the coffee and bacon are done? (Assume that the appliances are in a parallel circuit.) Will it matter if Jim has the overhead light (100-watt) on or not?

PLEASE SHOW WORK

THANKS

Explanation / Answer

assuming house hold supply voltage as

V=120 Volts

so

Total power consumed with toaster on

P=1000+600+700

P=2300 Watts

Total current consumed by applainces

I=P/V =2300/120

I=19.17 A

Yes Jim can start the toast as total current consumed by appliances is less than the 20 A fuse capacitity

b)

if jim has another overhead light ,the toal power is

P=2300+100=2400 Watts

total Current consumed by appliance

I=P/V=2400/120

I=20 A

so it is not recommende to turn on the toaster as total current equal the 20 A fuse current carrying capacity because fuse melts if toaster is turned ON.

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