Question #1) A student is using a sensitive meter that measures resistance finds

Question

Question #1) A student is using a sensitive meter that measures resistance finds that the resistance of a thin wire is changed slightly when it is picked up with a bare hand. What causes the change in the resistance, and does it increase or decrease? Please explain.

Question #2) Which costs more, running a 1,200-W hair dryer for 5 minutes or leaving a 60-W lamp on overnight (10 hours)?  Please Explain

Question #3) Compute the power consumption of an electric heater drawing 12 A from a  120 V power source. Please Explain

Explanation / Answer

1. Due to body temperature, its resistance will increase because resistance is directly proportionla to the temperature.

2. 1,200-W hair dryer for 5 minutes = 0.1 KWh and 60-W lamp on overnight (10 hours) = 0.6 KWh

So, lamp will cost more...

3. Power = P = VI = 12*120 = 1440 VA

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