Question

When the current and voltage of an electric circuit is given. Then power can be calculated by:
A. multiplying the current by the difference between the voltage going into and going out of the device.
B. multiplying the resistance by the resistance and the current.
C. multiplying the voltage by the difference between going into and going out of the device.
D. multiplying the current by the voltage.
E. multiplying the current by the resistance.

Answer 1

Hint Power is defined as the rate of the energy is transformed or transferred over time. We measure power in units of joules/second. It is also measured in watts.

Complete step by step solution
An electric circuit is capable of transferring power. Current is the rate of the flow of charge and voltage measures the energy transferred per unit of charge and the current is analysis as the number of the charges per unit time passing through a boundary. Since current is the amount of charge passing through a boundary in a fixed amount of time.
Power is defined as the current in the circuit and it is multiplied by the voltage of the energy source like battery.
The Power of a battery is expressed as,
Power $P = V \times I$
Here, V is the voltage of the battery.
Voltage is proportional to the current and the resistance of the battery.
$V = IR.$
Substitute,
$P = \left( {IR} \right) \times R$
$P = I{R^2}$.

Therefore, power can be calculated by the multiplying by the current and the resistance.
Hence, from the above options, option E is correct.

Note In the question, we solve by using the equation of power. Power is proportional to the voltage and the current. By using the equation of ohm’s law we substitute that in the equation of the power. It says that the current through a conductor between the points is proportional to the voltage across the points.