Question

What voltage must be applied to a 6.4-ohm lamp filament to develop 20 amperes of current?

Answer 1

We are asked to find the voltage that must be applied to a 6.4 ohm lamp filament to develop a current of 20 amperes.

Recall that Ohm's law is given by

$V=IR$

Where V is the voltage, I is current, and R is the resistance.

Substitute the given values

$\begin{gathered} V=20\times6.4 \\ V=128\; \text{volts} \end{gathered}$

Therefore, a voltage of 128 volts must be applied.