How to Calculate Resistance, Current, and Effective Resistance in a Series Circuit
Given the data of two lamps rated 60W; 240V and 100W, 240V respectively connected in series to a 240V power source:
a) What is the resistance of each lamp?
b) What is the effective resistance of the circuit?
c) How much current is passing through the lamps?
Answer:
See the answers below.
The total power of the circuit is equal to the sum of the powers of each lamp.
P = 60 + 100 = 160W
Now, with a voltage source of 240V, we can find the current in the circuit using the formula P = V * I.
I = P / V = 160 / 240 = 0.67 amp
Therefore, the answer for c) is 0.67 amp
Using Ohm's law, we can find the resistance of each lamp.
a) For the 60W lamp:
R = V^2 / P = 240^2 / 60 = 133.33 ohms
b) For the 100W lamp:
R = V^2 / P = 240^2 / 100 = 225 ohms
To find the effective resistance of the circuit in series, we sum the resistances:
Effective resistance = 133.33 + 225 = 358.33 ohms