You and a friend are studying late at night. There are three 170 W light bulbs a

Question

You and a friend are studying late at night. There are three 170 W light bulbs and a radio with an internal resistance of 53.0 ? plugged into the living room electrical outlets. You decide to have a break and have a snack, turning on the pop-corn machine that draws 8.00 A. How much electrical power are you using? Data: Assume the electric company provide you with 110 V potential difference.

All the electrical outlets are part of the same 110-V circuit which has a 10-A circuit breaker. How much current in amperes (A) is required to feed all the devices described above? This tells you if you should or should not turn on the pop-corn machine.

You are so tired after studying that you leave all of these household devices turned on for 13.0 hours. Calculate the cost (in dollars) of the electric bill, if the commercial rate is $.09/kWh? (Do not

Explanation / Answer

a)

Power consumed by 3 bulbs

P=3*`170=510 W

Power consumed by radio

P2=V^2/R =110^2/53

P2=228.3 W

Power consumed by pop-corn machine

P3=VI=110*8 =880 W

Total power

P=P1+P2+P3

P=1618.3 W

b)

Bulbs

I1=P/V=510/110 =4.64 A

Radio

I2 =V/R =110/53 =2.08 A

Popcorn machine

I3=8 A

total current

I=I1+I2+I3

I=14.72 A

so we should not turn on the Popcorn machine ,because in that case toal current exceeds rated current of circuit breaker ,so it will get trip.

c)

E =Pt =(1618.3/1000)*13

E=21.03 KWH

Cost =$0.09*21.08=$1.893

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

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