How can I calculate voltage drop in a parallel circuit?

Hint: This can be solved by using ohm’s law which states that voltage across a conductor is directly proportional to the current flowing through it, and for parallel circuits we will use formula for total resistance to find total voltage drop.

Formula used:
$\begin{align}
  & V=IR \\
 & R={{R}_{1}}+{{R}_{2}}+{{R}_{3}} \\
\end{align}$

Complete step by step solution:
The voltage drop across a resistor in a parallel circuit is the same across all the resistors in each branch of all the parallel circuits in the parallel circuit diagram.

Voltage expressed in voltage measures the electromotive forces that drive the circuit or the potential difference.

Consider a circuit with the three resistors connected in parallel and with the voltage supply ‘V’ and the current flowing in ‘I’.

Now step by step method to calculate voltage across the circuit,
Step 1:- find the total resistance of the parallel circuit.
Formula for total resistance for the circuit connected in parallel,
$\begin{align}
  & \Rightarrow \dfrac{1}{{{R}_{T}}}=\dfrac{1}{{{R}_{1}}}+\dfrac{1}{{{R}_{2}}}+\dfrac{1}{{{R}_{3}}} \\
 & \therefore {{R}_{T}}=\dfrac{{{R}_{1}}{{R}_{2}}{{R}_{3}}}{{{R}_{1}}{{R}_{2}}+{{R}_{2}}{{R}_{3}}+{{R}_{1}}{{R}_{3}}}....\left( 3 \right) \\
\end{align}$

Now according to the ohm’s law,
$\Rightarrow V=I{{R}_{T}}$
Where, V = voltage
I = current
${{R}_{T}}$ = total resistance
$\Rightarrow V=\dfrac{I\times {{R}_{1}}{{R}_{2}}{{R}_{3}}}{{{R}_{1}}{{R}_{2}}+{{R}_{2}}{{R}_{3}}+{{R}_{3}}{{R}_{4}}}....\left( 1 \right)$
Consider this method because according to Kirchhoff’s current law, the amount of the current entering in the circuit is equal to amount of the current leaving the circuit.

Note:
As an approach to solve this question we use ohm’s law to find voltage across a circuit of the resistor which are connected in parallel using total resistance of parallel circuit and total amount of current flowing in the circuit.