Two bulbs 100W,250V and 200W,250V are connected in series across a 500V line. Then what will happen?? a)100W will fuse b)200W will fuse c)both will fuse d)no bulb will fuse

1 Answer
devi f.
Feb 26, 2018

The 100W bulb will fuse soon.

Explanation:

Power =#V^2/R#, so Resitance R= #V^2/P#

The 100W bulb has a resistance =#(250 *250)/100#=625 ohms
The 200 W bulb resistance will be half above = 312.5ohms
Total resistance in series - 937.5 ohms

So total series current = #V/R# = #500/937.5# =0.533A

Power dissipated in Bulb 1: #I^2*R# = #0.533^2*625# =177.5W
Power dissipated in Bulb 2 wil be half above: 88.5 W

Bulb1 , a 100W unit, will eventually burnout.

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