> Power and voltage question?

Power and voltage question?

Posted at: 2015-01-07 
Almost there, minor math error then finish





then



P=V^2/R



=109^2/11.077ohm



=1072.59W





so drop is



1300 - 1072.59 = 227.41 W

It is not necessary to calculate the actual resistance since it was given that the resistance remains constant..





Stove burner output power drop = (power at 120V) - (power at 109V) = 1300W - {[(109V/120V)^2]*(1300W)} = 227.41 Watts

Looks right to me. Maybe you just forgot to subtract? THe question is asking about the drop, so you need:

1300 - 1073.26 = 224.74 W

Ah, Damon is right, I didn't check the arithmetic....

1300W-1073.26W=226.74W drop

what am I doing wrong?





During a "brownout", the power-line voltage drops from 120 V to 109 V. By how many watts does the thermal power output of a 1300 W stove burner drop, assuming the resistance remains constant?





(work)



R=V^2/P



=120^2/1300W



=11.077 ohm





then



P=V^2/R



=109^2/11.077ohm



=1073.26 W