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  • The bubs are made and the resistance of the filament increases with the increase in temperature. If at room temperature, 80 <img alt="\small \omega" src="https://entrancecorner.oncodecogs

The bubs are made and the resistance of the filament increases with the increase in temperature. If at room temperature, 80 \small \omega, 60 \small \omega and 20 \small \omega  bulbs have filament resistance \small R_{80},\ R_{60} and \small R_{20}. respectively, the relation between these resistances are:-

 

Option: 1

\frac{1}{R_{80}}=\frac{1}{R_{60}}+\frac{1}{R_{20}}


Option: 2

R_{100}>R_{60}>R_{40}


Option: 3

R_{100}=R_{60}+R_{20}


Option: 4

\frac{1}{R_{100}}>\frac{1}{R_{20}}>\frac{1}{R_{60}}


Answers (1)

best_answer

P=\frac{V^2}{R} 

Since same voltage is applied across all bulbs.

\\So, \\80 \omega>60 \omega>20 \omega

\frac{V^2}{R_{80}}>\frac{V^2}{R_{60}}>\frac{V_2}{R_{20}}

\Rightarrow \frac{1}{R_{80}}>\frac{1}{R_{60}}>\frac{1}{R_{20}}

80 \omega=60 \omega+20\omega \text { [At room temperature}]

So,

\frac{V^2}{R_{80}}=\frac{8^2}{R_{60}}+\frac{V^ 2}{R_{20}}

\frac{1}{R_{80}}=\frac{1}{R_{60}}+\frac{1}{R_{20}}

 

Posted by

Rishabh

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