How to Calculate Current and Resistance of a Light Bulb
What are the steps to calculate the current and resistance of a light bulb given the power and voltage?
Given Information:
Power = P = 100 Watts
Voltage = V = 220 Volts
Required Information:
a) Current = I = ?
b) Resistance = R = ?
Answer:
a) Current = I = 0.4545 A
b) Resistance = R = 484 Ω
According to the Ohm’s law, the power dissipated in the light bulb is given by
P = VI
Where V is the voltage across the light bulb, I is the current flowing through the light bulb, and P is the power dissipated in the light bulb.
Re-arranging the above equation for current I yields,
I = P/V
I = 100/220
I = 0.4545 A
Therefore, 0.4545 A current is flowing through the light bulb.
According to the Ohm’s law, the voltage across the light bulb is given by
V = IR
Where V is the voltage across the light bulb, I is the current flowing through the light bulb, and R is the resistance of the light bulb.
Re-arranging the above equation for resistance R yields,
R = V/I
R = 220/0.4545
R = 484 Ω
Therefore, the resistance of the bulb is 484 Ω