Question

A power source supplies a prescribed voltage and is used to power a light bulb if another light bulb is connected in series to the first how would it affect the current in the power source?.

Answer 1

The current from the power source will not change when the second light bulb is attached. This is because the current is kept on a single path, it will return to the power source at the same value it left the source at.

Answer 2

Answer: It would decrease.

Explanation:

From Ohm's law:

I = V/R

I = current

V = voltage

R = Resistance

The power source supplies a fixed voltage (V). Let the resistance of each light bulb be R.

When a light bulb is connected across voltage V, current I = V/R flows in the circuit.

When another bulb is added in series, the net resistance increases:

R' = R + R = 2 R

Because of increase in resistance, the current drawn in circuit decreases.

⇒ I' = V/2 R = I/2