Question

Initially bulbs A and B in FIGURE Q28.9 are glowing. What happens to each bulb if the switch is closed? Does it get brighter, stay the same, get dimmer, or go out? Explain.

Short answer

Bulb A gets brighter while bulb B goes out

Step-by-step solution

Given information and formula used

Given :

Theory used :

When current passes through a resistor, it dissipates energy, and the rate at which this energy is dissipated is the power. The rate at which energy is transferred from the current to the resistor is

$P_R=I^{2}R$

Determining if the bulbs get brighter, stay the same, get dimmer, or go out 

The current through the resistor determines how much electricity passes through it. The current prefers to travel through the short circuit wire rather than bulb B when the switch is closed.

As a result, there is no current flowing through bulb B.

So, bulb A gets brighter while bulb B goes out in this example.