Question

Assuming that voltage remains constant, what happens to the current in a filament if it is replaced by a longer wire?
A. The current increases.
B. The current decreases.
C. The current is not affected by a change in filament length.
D. The current alternates between high and low values.

Answer 1

Answer:

Choice B: The current decreases.

Explanation:

The resistance of a conductor is proportional to its length when radius and resistivity stays the same. The resistance of the longer filament will be greater than the resistance of the initial one.

For Ohmic conductors,

$\displaystyle I = \frac{V}{R}$,

where

• $I$ is the current through the conductor,
• $V$ is the voltage across the conductor, and
• $R$ is the resistance of the conductor.

Voltage here stays the same. Increasing the resistance $R$ of the conductor will reduce the current.

The filament might heat up over time. The filament might not be an ohmic conductor. Still, a similar trend shall exist. Resistance will be greater in the longer filament, and current will decrease.

Answer 2

Answer:

The current decreases

Explanation: