Current Electricity Ques 104
- Incandescent bulbs are designed by keeping in mind that the resistance of their filament increases with the increase in temperature. If at room temperature, $100 $ $W, 60$ $ W$ and $40$ $ W$ bulbs have filament resistances $R _{100}, R _{60}$ and $R _{40}$, respectively, the relation between these resistances is (2010)
(a) $\frac{1}{R _{100}}=\frac{1}{R _{40}}+\frac{1}{R _{60}}$
(b) $R _{100}=R _{40}+R _{60}$
(c) $R _{100}>R _{60}>R _{40}$
(d) $\frac{1}{R _{100}}>\frac{1}{R _{60}}>\frac{1}{R _{40}}$
Show Answer
Answer:
Correct Answer: 104.(d)
Solution:
Formula:
- $R=\frac{V^{2}}{P}$ or $R \propto \frac{1}{P}$
$ \therefore \quad \frac{1}{R _{100}}>\frac{1}{R _{60}}>\frac{1}{R _{40}} $
Hence, the correct option is (d).
BETA
