Question

A current of $3A$ flows through a resistance when it is connected across a 12V source. What should the current be if the resistance is increased by $4\Omega$ and connected across the same voltage source?

• A. $1.5A$
• B. 4 A
• C. 1.6 A
• D. 24 A

Answer 1

The correct option is A $1.5A$

$\underset{–}{\text{First Case:}}$

Voltage $V_1=12V$

Current $I=3A$

Resistance = $R$

From Ohm's law: $12=3\times R$

$\therefore R=\frac{12}{3}=4\Omega$

$\underset{–}{\text{Second Case:}}$

Voltage $V_2=12V$

Resistance = $R+4=8\Omega$

From Ohm's law: $12=I^{\prime }\times 8$

$\therefore I^{\prime }=\frac{12}{8}=1.5A$