2 electric bulbs rated 100w 220v and 60w 220v are connected in parallel to electric main of 220v .Find total current
Answers
Given,
First condition:
=> Power = P = 100 W
=> Voltage = V = 220v
=> Resistance = R
Formula of power = P = V²/R
▪️ According to Formula of Power:
100 = 220 ×220/R
R = 220 × 220/100
= 484 Ω
In second condition,
Given,
=> Power = P = 60 W
=> Voltage = V = 220v
=> Resistance = R
▪️ According to Formula of Power:
P = V²/R
60 = 220 × 220/R
R = 220× 220/60
= 806.7 Ω
In question, it is given that, resistors are connected in parallel
Therefore,
➡️ total resistance = 1/R
1/R = 1/484 + 1/806.7
= 806.7 + 484/484×806.7
= 1290.7/390442.8
R = 390442.8/ 1290.7
R = 302.5 ohms
We get, Resistance as 302.5 ohms.
Now,
▪️ We have to find Voltage:
V = IR
220 = I × 302.5
I = 220/302.5
= 0.73 A
◼️ Hence, Total current drawn is 0.73 A