Current Electricity Charging Discharging Of Capacitors Question 732
Question: Water boils in the electric kettle in 15 minutes after switching on. If the length of heating wire is decreased to 2/3 of its initial value, then the same amount of water will boil with the same supply voltage in
Options:
A) 8 minutes
B) 10 minutes
C) 12 minutes
D) 15 minutes
Show Answer
Answer:
Correct Answer: B
Solution:
[b] $ H=\frac{V^{2}}{R}\times 15\times 60=\frac{V^{2}}{( 2/3 )/R}\times t $
$ \text{or }t=\frac{2}{3}\times 15\times 60=600s=10\text{ minutes}\text{.} $
BETA
