Power Formula

Definition

Power (P) Energy transferred or work done per unit of time is the measure of the rate at which work is done or energy is being transferred from one form to another.

The Power Formula

The basic formula for power (P) is: P=Wt

Where:

• P = Power

• W = Work done (or energy transferred)

• t  = Time

Units of Power

• SI Unit: The unit of power in the International System of Units (SI) is the watt (W).

• 1 watt = 1 joule/second (1 W = 1 J/s)

For any electrical circuit, the power is calculated using these three equations

In terms of Voltage and current, it is expressed as

P = V×I

In terms of current and resistance, it is expressed as

 P=I2R

Voltage and resistance, It is expressed as

P=V2R

Where,

A voltage applied across the two ends =V,

Current flowing in the circuit = I and 

Resistance = R

The formula of Power is utilized to calculate the Power, Resistance, Voltage, or current in an electric circuit. The standard unit of power, in metric, is the Watt.

Solved Examples

Problem 1: An electric machine uses 300 J energy to do work in 10s. What power does it employ?

Answer:

Given: Work done = W = 300 J,

Time taken t = 10 s.

The power used by it is given as

Problem 2: John, who has a mass of 60 kg runs up to 12m high in 40 seconds. Calculate his power.

Answer:

Known: m (mass) = 60 kg,

h = height = 12 m,

t (time taken) = 40 seconds.

Power is given by:

Conclusion

Understanding power allows one to analyze how efficiently work is done or how energy is used. Mastery of the basic formula and its applications is indispensable in solving problems both in physics and real life.

 

Other Related Sections

NCERT Solutions | Sample Papers | CBSE SYLLABUS| Calculators | Converters | Stories For Kids | Poems for kids| Learning Concepts I Practice Worksheets I Formulas | Blogs | Parent Resource