Assignment Help: How much thermal energy is produced in..

Q) A 1250 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 1.0 h?

Sol:

a) We can calculate the current ‘I’ from the power and voltage.

P = IV

I = P/V

= 1250/115

=10.87A

b) We can calculate the Resistance ‘R’ from the Voltage and power

P = V²/R

R = V²/P

= (115)²/1250

=10.58ohms

c) Thermal energy ‘U’ produced in 1 hr=3600secs is given by,

U = P * t =1250 *3600 = 4.5 *10⁶J