A filament bulb (500w , 100 v) is to be used in 230v main supply . When resistance R is connected in series , it works perfectly and the bulb consumes 500w . The value of R is.

Q. An electric bulb is rated 500 W and 100 V is used in 200 V supply. Calculate the resistance R which is connected in series to the bulb so that the bulb delivers 500 W.

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A filament bulb 500 W, 100 V is to be used in a 230 V main supply. When a resistance R is connected in series, it works perfectly and the bulb consumes 500 W . The value of R is :-

The correct option is A 26ΩIfR=rPmax=E24rρ=VII=ρVB=500100=5AVR=IR=(230−100)=5RR=26ΩHence,optionAisthecorrectanswer.

The correct option is A 26 $Ω$
$\begin{matrix} I f R = r P_{max} = \frac{E^{2}}{4 r} ρ = V I I = \frac{ρ}{V_{B}} = \frac{500}{100} = 5 A V_{R} = I R = (230 - 100) = 5 R R = 26 Ω H e n c e, o p t i o n A i s t h e c o r r e c t a n s w e r . \end{matrix}$