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CBSE Class 12 Physics 2018 Delhi Set 1 Paper

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Question : 6 of 26
Marks: +1, -0
SECTION -B
Two electric bulbs PP and QQ have their resistances in the ratio of 1:21: 2. They are connected in series across a battery. Find the ratio of the power dissipation in these bulbs.
Solution:  
Formula
   Stating that currents are equal \;\text{ Stating that currents are equal }
   Ratio of powers \;\text{ Ratio of powers }
   Power   =R2R\;\text{ Power }\;=R^2 R
The current, in the two bulbs, is the same as they are connected in series.
∴      P1P2  =  I2R1I2R2=  R1R2\therefore \;\; \; \frac{P_1}{P_2} \; = \; \frac{I^2 R_1}{I^2 R_2} = \; \frac{R_1}{R_2}
  =  12\; = \; \frac{1}{2}
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