Current Electricity Charging Discharging Of Capacitors Question 571
Question: The resistance of hot tungsten filament is about 10 times the cold resistance. What will be the resistance of 100 W and 200 V lamp when not in use
[AIEEE 2005]
Options:
A) $ 400,\Omega $
B) $ 200,\Omega $
C) $ 40\Omega $
D) $ 20,\Omega $
Show Answer
Answer:
Correct Answer: C
Solution:
It is given $ R _{Hot}=10,R _{Cold} $ also resistance at rated temperature $ R=\frac{V^{2}}{P}=\frac{200\times 200}{100}=400,\Omega $ . So resistance when lamp not in use. $ R _{Cold}=\frac{R _{Hot}}{10}=\frac{400}{10}=40,\Omega $
BETA
