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Power and Energy

A perfectly insulated container contains 70 g of water and has a small heater immersed in water. The temperature of the water is 40 degrees Celsius, and the heater is connected to a 12V battery via a switch. When the heater is switched on, an electric current of 13A flows through its heating element and the temperature of the water starts to rise.

The values for the specific heat of water and latent heat of vaporization are in the attached file.

1. Kindly list the data given above. Along each item of data, write the appropriate symbol for that quantity. Thanks.

2. Calculate:
a. the power supplied by the heater
b. the energy required for the water to reach boiling temperature (100 degrees Celsius).
c. the time taken for the water to reach boiling temperature
d. the energy required to vaporize all the water.
e. the time taken to vaporize all water


Solution Preview

Joules = watts x seconds

1. Mass of water = m = 70 g = 0.07 kg
Water initial temperature = Ti = 40 deg. C
Battery Voltage = V = 12V
Current through heater = I = 13A
The specific ...

Solution Summary

This solution describes the uses of power and energy.