The circuit shown to the right is arranged with resistors li

The circuit shown to the right is arranged with resistors, light bulbs (labeled A and B), and an unknown battery. (a) Is bulb A brighter than, dimmer than, or the same brightness as bulb B? Explain your reasoning. (b) If 2.0 A flows through Bulb A, what is the voltage (EMF) of the battery?

Solution

Here ,
Here ,

part a)

as the current in bulb B will be greater than the current in bulb A

as Brightness = I^2 * R

resistance of B

hence , the bulb B will be brighter than bulb A.

part B)

for the equivalent resistance

Req = 6 + 3 + 3 + 10 + 3 * 6/(3 + 6)

Req = 24 Ohm

EMF of battery = Req * I

EMF of battery = 24 * 2

EMF of battery = 48 V