Question

Suppose you have three identical lightbulbs, some wire, and a battery. You connect one lightbulb to the battery and take note of its brightness. You add a second lightbulb, connecting it in parallel with the previous lightbulbs, again take note of the brightness. Repeat the process with the third lightbulb, connecting it in parallel with the other two. As the lightbulbs are added, how are the following properties affected? (Neglect the battery's internal resistance)

brightness of the bulb ---Select--- increases decreases remains unchanged
individual currents in the bulb ---Select--- increases decreases remains unchanged
power delivered by the battery ---Select--- increases decreases remains unchanged
lifetime of the battery ---Select--- increases decreases remains unchanged

Answer 1

Step-by-step explanation:

Brightness of the bulb remains the same .

It is so because as lightbulb is added in parallel combination , the potential over each bulb remains same . Resistance is also same so according to the following formula for power , heat generated will be same .

Power = V² / R

On the same principle , current also remains the same .

Current = V / R , V and R are same for all .

Power of the battery

= V² / R where R is resistance of the circuit . As the bulb is added in parallel , total resistance of circuit decreases , hence power increases .

Power by battery increases .

As power increases , lifetime decreases because energy is dissipated

by battery at greater speed.