Chapter 35, Problem 47A

A 60-W bulb and a 100-W bulb are connected in series in a circuit.

a. Which bulb has the greater current flowing in it?

b. Which has the greater current when they are connected in parallel?

To determine

The bulb in which the greater current is flowing in it.

Explanation of Solution

Introduction:

In a series circuit, the bulbs are connected in series. So, the current across each bulb will remain same.

The resistance opposes the flow of current. The voltage across each bulb varies while the current remains the same. Therefore, $60\text{W}$ bulb and $100\text{W}$ bulb will have the same current.

Conclusion:

  $60\text{W}$ bulb and $100\text{W}$ bulb will have same current.

To determine

The bulb for greater current flow in parallel connection.

Explanation of Solution

Introduction:

The voltage in the parallel connection across each bulb remains the same.

The resistance of both bulbs is the same. So, the current flow depends on the power of the bulbs. The more power of the bulb provides more energy for the flow of electrons.

The current through $100\text{W}$ is greater than $60\text{W}$ bulb because $100\text{W}$ needs more current for glowing than $60\text{W}$ in parallel connection.

Conclusion:

The current through $100\text{W}$ is greater than $60\text{W}$ bulb because $100\text{W}$ needs more current for glowing than $60\text{W}$ in parallel connection.