Question

An electric device, which heats water by immersing a resistance wire in the water, generates 20 cal of heat

per second when an electric potential difference of 6 V is placed across its leads. What is the resistance in Ω

of the heater wire? (Note: 1 cal = 4.186 J)

Select one:
a. 0.86
b. 0.17
c. 0.29
d. 0.43

Answer 1

1 cal/s =4.184w

p=50 cal/s =2093w

v=12v

P = V*I

I =P/V

I = 17.43 A

P =1²*R

R = P/I²

R = 0.68