This is meant to be handed out to the students.
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constant you might need :
C of water = 1 calorie/(° C gram)
[1 calorie = 4.2 Joules = 42,000,000 (4 x 10
) ergs]
formulas you might need :
Elec.Energy = (Elec.Power) x t
Elec.Power = V
/R
Thermal Energy = m C (T - T
)
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1. (2 pts.) A 200-Watt light bulb is on for 30 hours. How much electrical energy is consumed? Express your answer in units of kilowatt-hours. (A kilowatt is 1000 watts.)
2. (3 pts.) A resistor is dropped in a thermos of water. The resistor is 1 ohm, and a voltage of 4 V is applied for 20 minutes (1200 seconds). How much energy is dissipated in the resistor (Units!)?
Important Disclaimers and Caveats