5 Electric Energy Electric Power Combination of resistors

Electric Energy Electric Power Combination of resistors

Electric Energy

Work done by the source of emf in maintaining the electric current in the circuit for a given time is called electric energy consumed in the circuit.

V = IR

q = It

W =Vq

∴W= VIt

Where,

V → Potential difference

I → Current

R → Resistance

q → Charge

t → Time

W → Work done

• V is in volt, I in ampere, and t in seconds. The energy dissipated is in Joule.

Electric Power

• It is the rate at which work is done by the source of emf in maintaining the electric current in a circuit.

Where,

W → Work done

t → Time

P → Electric power

• SI unit of power is watt.
• Expression of electric power in terms of

• V and I

P = VI

• I and R

P = I² R

• V and R

Combination of resistors

Resistors in Series

• Two or more resistors are said to be connected in series, if same current passes through each of them, when a potential difference is applied across them.

Equivalent resistance, R_S = R₁ + R₂ + R₃

Resistors in Parallel

• Two or more resistors are said to be connected in parallel, if potential difference across each of them is equal to the applied potential difference.

• Equivalent resistance (R_P)