Calculating Thermal Energy Supplied by Heater in 30.0s - Kilo-joules

[questionmaster]

A heater has a resistance of 15.0 W. It operates on 120.0 V. What thermal energy is supplied by the heater in 30.0 seconds? Answer must be in Kilo-joules.


Well o_o ..it would be nice if you could try to help me with this question. Since I recently moved from Germany to the U.S. with my parents.. and we weren't at this point in my old school.

 

[Tide]

Do you mean 15 Ohms resistance?

Use Ohm's Law to calculate the power usage (voltage times current) and note that energy = power times time.

 

[The Bob]

A heater has a resistance of 15.0 W. It operates on 120.0 V. What thermal energy is supplied by the heater in 30.0 seconds? Answer must be in Kilo-joules.

Voltage (volts) = Current (amps) x Resistance (ohms)
Power (watts) = Voltage (volts) x Current (amps)

Therefore:
Resistance (ohms) = Power (watts)

Energy Transfer (J) = Power (W) x Time (s) => E = 15 x 30
=> Answer should be 450 J or 0.45 kJ.

The Bob (2004 ©)