Question

What is called the rate of doing work in an electric circuit?
a.)Power
b.)Energy
c.)Current
d.)Voltage

Answer 1

Hint: When charges move in an electric circuit, they carry some electrical energy associated with them. When they move from a region of higher to lower or lower to higher potential difference, work is done in the circuit. The rate of doing work can be measured by taking the amount of energy transferred and the time for which charges were in motion.

Complete step by step answer:
Electric power is a form of mechanical power, and is defined as the rate of work done. It can also be expressed as the rate of consumption of electrical energy per unit time. Electric Power is described as the rate at which work is done or energy is transformed into an electrical circuit. It is a measurement of how much energy is used in a span of time.

Expression for Electrical Power in a circuit,

$\text{Power = }\dfrac{\text{Energy}}{\text{time}}$

Electrical energy is given by,
$E=VQ$
Therefore,
$P=\dfrac{VQ}{t}$

Where,
\[V\] is electric potential in volts
$Q$is electric charge in Coulombs
$t$ is time in seconds

Electric power is essentially the rate, described per unit time, at which electrical energy or electricity is passed or transferred by an electric circuit. Power can be measured in different units. The SI unit for the measurement of power is Watt; 1 watt is equal to one joule per second.

Hence, the correct option is A.

Additional information:
When electric charges, positive or negative, move through a potential difference of some value, from a higher voltage to a lower voltage, that is, when conventional current, called as positive charge, moves from the positive terminal of circuit to its negative terminal, work is done by the respective charges on the device. The potential energy of these charges due to the voltage difference between the terminals of the circuit is converted to the kinetic energy of the device. These devices are known as passive components or loads, because they consume electric power from the circuit and convert it into the other forms of energy such as heat, light, or mechanical work. Examples of such devices are electrical appliances like light bulbs, electric motors, and electric heaters.

Note:
Students should not get confused between the term energy and power. Electrical energy is the electric charge doing work. The rate at which energy gets transferred in the circuit is called power. Electric power can be transformed into other forms of energy when electric charge moves through some electric potential, or voltage difference, which occurs in the electrical components in electric circuits.