Question

A potential difference of 4 volt is applied to two resistors of 6Ω
and 12Ω connected in parallel. Calculate
(a) Find (i) Total resistance in the circuit
(ii) Total current flowing (iii) the potential difference across 6Ω
resistor.
(b) What is meant by electric power? Write the formula for
electric power in terms of potential difference and current.

Answer 1

(a) Potential difference = 4V

Resistance = 6Ω, 12Ω

Total resistance =

$\frac{1}{R_t} = \frac{1}{6} + \frac{1}{12}$

$\frac{1}{R_t} = \frac{2 + 1}{12}$

$\frac{1}{R_t} = \frac{3}{12}$

$\frac{1}{R_t} = \frac{1}{4}$

$R_t = 4 \: Ω$

Total Resistance = 4 Ω

$(ii) Current (I) = \frac{ Voltage(V)}{ Resistance (R_t) }$

$I= \frac{6}{4}$

$I = 1.5 \: A$

(iii) The Potential Difference remains same when resistors are connected in parallel.

Therefore, potential difference = 6 V

(b) Electric Power is the amount of electric energy transferred in unit time by current. The SI unit of power is Watt.

$1 \: Watt = \dfrac{ 1 \: Joule}{ 1 \: second}$