Advertisements
Advertisements
प्रश्न
A 100 W electric lamp emits energy in the form of light at the rate 10 J per second. What percentage of electric energy does the lamp transform into light energy?
Advertisements
उत्तर
Given power of lamp = 100 watt
rate of dissipation of light = 10 J/s
Therefore, percentage of electrical energy converted into light energy = `10/100 xx 100%` = 10%
APPEARS IN
संबंधित प्रश्न
In which of the following cases, is work being done?
(i) A man pushing a wall.
(ii) a coolie standing with a load of 12 kgf on his head.
(iii) A boy climbing up a staircase.
The power of a motor is 40 kW. At what speed can the motor raise a load of 20,000 N?
State two disadvantages of producing hydroelectricity.
Give one example in which a force does zero work.
A car is being driven by a force of 2.5 ✕ 1010 N. Travelling at a constant speed of 5 m/s, it takes 2 minutes to reach a certain place. Calculate the work done.
How many joules are there in 1 mega joule?
Is power a scalar quantity?
A woman pulls a bucket of water of total mass 5 kg from a well which is 10 s. calculate the power used by her.
State the energy changes which take place when A stone dropped from the top of a cliff reaches the ground after some time.
