A current of 2 A is passed through a coil of resistance 75 ohm for 2 minute. (a) How much heat energy is produced? (b) How much charge is passed through the resistance?
Answers
ANSWER
In any electrical appliance their is a simple relationship between the power output of a component, the potential difference across that component, and the current running through it. This is because charge times potential difference is energy, so (charge per unit time) times (potential difference) gives (energy per unit time). Thus, we have P=VI.
Substituting V=IR from ohm's law, the power relationship can be rewritten as P=I
2
R. If the time factor is taken into consideration, then the power is calculated as P=I
2
Rt where t is the time taken in seconds to generate this power. From this formula, the heat generated can be calculated as follows.
In this case, a current of 2 A is passed through a coil of resistance 75 ohm for 2 minutes, that is, 120 seconds. Therefore, the heat generated is H=2
2
×75×120=36000Joules.
Hence, the amount of heat energy produced is 36000 Joules.