If 200w, 100 w and 60 w lamps connected in series with 230V AC , which lamp glow brighter? Each lamp voltage rating is 230V.

 If 200w, 100 w and 60 w lamps connected in series with 230V AC , which lamp glow brighter? Each lamp voltage rating is 230V.

§  Each bulb when independently working will have currents (W/V= I)

§  For 200 Watt Bulb current (I200) =200/230=0.8696 A

§  For 100 Watt Bulb current (I100) =100/230=0.4348 A

§  For 60 Watt Bulb current (I60) =60/230=0.2609 A

§  Resistance of each bulb filament is (V/I = R)

§  For 200 Watt Bulb R200= 230/0.8696= 264.5 ohms

§  For 100 Watt Bulb R100= 230/0.4348 = 528.98 ohms and

§  For 60 Watt Bulb R60= 230/0.2609=881.6 ohms respectively

§  Now, when in series, current flowing in all bulbs will be same. The energy released will be I²R

§  Thus, light output will be highest where resistance is highest. Thus, 60 watt bulb will be brightest.

§  The 60W lamp as it has highest resistance & minimum current requirement.

§  Highest voltage drop across it X I [which is common for all lamps] =s highest power.

§  Note to remember:

§  Lowest power-lamp has highest element resistance.

§  And highest resistance will drop highest voltage drop across it in a Series circuit

§  And highest resistance in a parallel circuit will pass minimum current through it. So minimum power dissipated across it as min current X equal Voltage across =s min power dissipation