To calculate the change in temperature, subtract the initial temperature from the final temperature. Example: 84.2 degree Fahrenheit - 41 degrees Fahrenheit = 43.2 degrees Fahrenheit. The temperature from morning to afternoon changed by 43.2 degrees Fahrenheit.
It needs 12 volts so it will be the standard modern power supply provides 12 volts of power.
After electricity is produced at power plants it has to get to the customers that use the electricity. Our cities, towns, states and the entire country are criss-crossed with power lines that carry the electricity. As large generators spin, they produce electricity with a voltage of about 25,000 volts.