Question

A projector lamp can be used at a maximum voltage of 60 V, its resistance is 20, the series resistance (in ohms) required to operate the lamp from a 75 V supply is

• A. 2
• B. 3
• C. 4
• D. 5

Answer 1

The correct option is D 5

$V_{bulb}=I\times 20\Rightarrow I=3A$
$\Rightarrow I_{R_{min}}=15$
$R_{min}=5\Omega$