Question

A resistor of 6 ohm is connected in series with another resistor of 4 ohm. A potential difference of 20 V is applied across the combination.
a) Calculate the current in the circuit and
b) potential difference across the 6 ohm resistor

Answer 1

Circuit diagram:
Equivalent resistance:
Given,
$R_1=6\Omega \text{and}{R}_2=4\Omega$ are in series
Total resistance $R_{eq}$ is
$R_{eq}=R_1+R_2=6+4=10\Omega$
(a) Current through the circuit:
Given,
Voltage of the battery, $V=20V$
Applying Ohm’s law for $R_{eq}$ , we get
$V=IReq$
Current through the circuit
$I=\frac{V}{R_{eq}}=\frac{20V}{10\Omega }=2A$
(b) Potential difference across 6 ohm resistor
Current through $R_1=6\Omega \text{resistor is}I=2A$
Applying Ohm’s law for $R_1=6\Omega$
$V_1=I{R}_1$
Thus, potential difference across the $6ohm$ resistor
$V_1=\left(2A\right)\times \left(6\Omega \right)=12V$