The total current delivered to a number of devices connected in parallel is the

Question

The total current delivered to a number of devices connected in parallel is the sum of the individual currents in each device. Circuit breakers are resettable automatic switches that protect against a dangerously large total current by "opening" to stop the current at a specified safe value. A 1500-W toaster, a 1040-W iron, and a 1000-W microwave oven are turned on in a kitchen. As the drawing shows, they are all connected through a 20 A circuit breaker (which has negligible resistance) to an ac voltage of 120 V.

(a) Find the equivalent resistance of the three devices.
?

(b) Obtain the total current delivered by the source.
A

Determine whether the breaker will "open" to prevent an accident.

The breaker will "open".

The breaker will remain "closed"

Explanation / Answer

total power = 1500 + 1040 + 1000 = 3540 V

voltage = v = 120 V

P = V^2/R

R = V^2/P = (120)^2/3540

Req = 4.068 ohm

part b )

I = V/R

I = 120/4.068 = 29.5 A

part c )

The breaker will open since breaker current is 20 A here current is 29.5 A

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