Question

A battery connected to a pair of parallel $30$ ohm resistor in series with a $9$ ohm resistor. The current through the $9$ ohm resistor is $0.25A$. Find out the voltage applied to the circuit?

• A. $1.5V$
• B. $3V$
• C. $6V$
• D. $12V$
• E. $24V$

Answer 1

The correct option is C $6V$

The equivalent resistance of pair of parallel 30 ohm resistor,

$\frac{1}{R^{\prime }}=\frac{1}{30}+\frac{1}{30}$

or $R^{\prime }=900/60=15\Omega$

now this equivalent resistance is in series with a 9 ohm resistor , so total resistance of the circuit ,

$R=15+9=24\Omega$

given that ,current $I=0.25A$

therefore , voltage applied to circuit $V=IR=0.25\times 24=6V$