Question

An electric motor takes 5 A from a 220 V line. Determine the power of the motor and the energy consumed in 2 h.

Answer 1

Power

1. Power is the energy consumed by a body in a unit time.
2. In general, power, $E=P\times t$, where, E is the energy, P is the power, and t is the time.
3. Power is defined by the form, $P=VI$, where, V is the supplied voltage and I is the current through the circuit.

Step 1: Given data

1. Supplied voltage, $V=220volt.$
2. The current through the motor is, $I=5A.$
3. the time of consumption is, $t=2h.$ or $2\times 60\times 60seconds=$ $7200seconds$

Step 2: Calculation of power

As we know, power is $P=VI$.

So,

$$\begin{gathered} P=220\times 5=1100 \\ orP=1100watt. \end{gathered}$$

Therefore, the power of the motor is $1100watt.$

Step 3: Calculation of energy consumption

We know that energy consumed by a body is $E=P\times t$.

So,

$$\begin{gathered} E=1100\times 7200 \\ orE=7920000joule. \\ orE=7.9\times {10}^{6}joule. \end{gathered}$$

Therefore, the energy consumed in 2 h by the motor is $7.9\times {10}^{6}joule.$