Work Power and Energy

Work is “expenditure of energy” Work and energy, both have same units of joules. Energy or word is used to overcome soma obstacle. For example boing a water. A cup of water need 90000 J to heat a cup of water .

Joules

Joule is defined as the energy dissipated as heat when an electric current of one ampere passes through a resistance of one ohm for one second. It is named after the English physicist James Prescott Joule.

Power

We have already defined power before as “rate of change of work/energy with respect to time”. It has a units of watts. Mathematically it is defined as

Similarly from here we can also derive formula for work. The unit is joules or watts.sec

Power and Voltage in circuit

Let’s say if we connect a lamp to a bulb to some battery, the battery will start providing energy, to the lamp.

The bulb will convert the electrical energy to light energy. Hence the power consumed by the lamp to provide us the lamp will depend on the amount of voltage or current associated with the lamp. We already know

If we multiply v and I we will get

Which is same as power , so concluding we can say that

Relation of Power and Ohms Law

As already discussed above, that power is directly proportional to the voltage and current passing through a element. Similarly, the power consumed by a device, also depends on resistance offered by the element to current and voltage. Hence we can also derive a formula for power with respect to the resistance, through which we need to calculate the power

As already discussed that , Ohms law gave us the following relation

Similarly we can find the expression of voltage through ohms law

Now if we put the equation A and B in our power formula we , will get new expression of power .