An electric kettle has two heating coils. when one coil is used, water in the kettle boils in 5 minutes, while when second coil is used, same water boils in 10 minutes. If the two coils, connected in parallel are used simultaneously.the same water will boil in timeA. 9 min 20 secB. 5 minC. 7 min 30 secD. 2 min 30 sec

An electric kettle has two heating coils. when one coil is used, water

1.	An electric kettle has two heating coils. when one coil is used, water in the kettle boils in 5 minutes, while when second coil is used, same water boils in 10 minutes. If the two coils, connected in parallel are used simultaneously.the same water will boil in timeA. 9 min 20 secB. 5 minC. 7 min 30 secD. 2 min 30 sec
Answer» Correct Answer - A (a) In parallel `(1)R_(P) = (1)/(t_(1)) + (1)/(t_(2)) = t_(P) = (t_(1) t_(2))/(t_(1) + t_(2))` `= (5 xx 10)/(5 + 10) = (50)/(15) = 3.33 m i n = 3 m i n 20 sec`

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