A light bulb is powered by a single D-cell. What happens if two D-cells connected end-to-end are used?

Question

Multiple choice question.

A)
The light bulb burns brighter because the current will be larger.

B)
The light bulb burns brighter because the current will be smaller.

C)
The light bulb burns dimmer because the current will be larger.

D)
The light bulb burns dimmer because the current will be smaller.

Answer 1

When two D-cells are connected end-to-end (in series), they effectively increase the voltage supplied to the light bulb. A single D-cell typically provides around 1.5 volts, so two D-cells in series would provide approximately 3 volts.

In general, when the voltage increases while the resistance of the light bulb remains the same, the current through the bulb will increase according to Ohm's Law (I = V/R). As a result, the light bulb will likely burn brighter.

Based on this reasoning, the correct answer would be:

A) The light bulb burns brighter because the current will be larger.