A 1210 W radiant heater is constructed to operate at 115 V. (a) What is the current in the heater when the unit is operating? (b) What is the resistance of the heating coil? (c) How much thermal energy is produced in 4.07 h?

(a) 10.52 A

(b) 11 ohm

(c) 1.77 x 10^7 J

Explanation:

P = 1210 W, V = 115 V,

Let i be the current.

(a) Use the formula of power

P = V i

1210 = 115 x i

i = 10.52 A

(b) Let the resistance of heating coil is R.

Use the formula given below

V = i x R

R = V / i = 115 / 10.52 = 11 ohm

(c) Use the formula for energy

E = V x i x t

E = 115 x 10.52 x 4.07 x 60 x 60 = 1.77 x 10^7 J