Three `100W, 150V` lamps are connected across a `150V power line as shown. Find (a) Voltage across each lamp and (b) total power dissipated in three bulbs.

Explanation

Resistance of each bulb `R_(B) = ((150)^2)/(100) = 225 Omega`

`V_(1) = (225//2)/((225/2+225) xx 150 = 50V`
`V_(2) = 150-50 = 100V`
`V_(x) = 150-50 = 100V`
`R_(eq) = 225+225/2 = 675/2 Omega`
Power consumed in the circuit
`P = ((150)^2)/((675//2)) = (150xx150xx2)/(675) = 66.7W`.
Or
`P=((P_(Y)+P_(Z))P_X)/((P_(Y)+P_(Z)+P_X) = (200xx100)/(300) = 66.7W`.