Question

An electric kettle has two heating coils. When one of them is switched on water in it boils in 6 minutes and when other is switched on water boils in 4 minutes. In what time will the water boil if both coil are switched on simultaneously
A. 1.6 min
B. 2.8 min
C. 2.4 min
D. 3 min

Answer 1

Correct Answer - C
`t_(S)=t_(1)+t_(2),t_(P)=(t_(1)t_(2))/(t_(1)+t_(2))`