It takes 4 minutes to boil a quantity of water electrically. How long will it take to boil same quantity of water using the same heating coil but with the current doubled? (neglecting any external heat loss).
-
A.
64 minutes -
B.
32 minutes -
C.
8 minutes -
D.
2 minutes -
E.
1 minute
Correct Answer: Option E
Explanation
D ∝ l2
E will increase 4 times when current is doubled.
Therefore time will decrease by a factor of 4, which is 1 minute.