Question

Water fall from a 40 m high dam at the rate of 9 × 104 kg per hour. Fifty percentage of gravitational potential energy can be converted into electrical energy. Using this hydroelectric energy number of 100W lamps, that can be lit, is ______. (Take g = 10 ms^-2)

Options

• 25

• 50

• 100

• 18

Answer 1

Water fall from a 40 m high dam at the rate of 9 × 104 kg per hour. Fifty percentage of gravitational potential energy can be converted into electrical energy. Using this hydroelectric energy number of 100W lamps, that can be lit, is 50. (Take g = 10 ms^-2)

Explanation:

Given

`1/2.(Delta"U")/(Delta"t")="P"_"Bulb"xx"N"`, where N = no. of bulb

⇒ `(9xx10^4xx10xx40)/(2xx3600)`

= 100 × N  `[∵ (Delta"U")/(Delta"t") = "mgh"/3600"J"/"S"]`

⇒ N = `(36xx10^6)/(72xx10^4)`

= `1/2xx100`

⇒ N = 50