Explanation:
Principle focus is the point on the axis of a convex lens, where the parallel rays of light from one side of the lens. meet on other side after refraction. Distance between optical centre to principle focus point is the focal length.
Answer:
Energy, 9 kWh or 32400 kJ
Explanation:
Given that,
The power of heater, P = 3 kW
It runs for 3 hours to raise the water temperature to the desired level. We need to find the amount of electric energy used. We know that the electrical power of an object is given by total energy delivered per unit time. It is given by :



E = 9 kWh
Since, 1 kWh = 3600 kJ
E = 32400 kJ
So, the amount of electric energy used is 9 kWh or 32400 kJ. Hence, this is the required solution.
Answer:
4s
Explanation:
when a bOdy rises into the air,the time it takes to reach a particular height is the same as the time it will take the body to fall from that height to the ground.
Not sure if this answer is write or wrong but i think its <span>4500 watts
</span>
“Yes, it is impossible to go around the curved path with zero acceleration. Acceleration is change in velocity. And velocity( speed+ direction) changes at every point in a curved path because there is change in direction at every point.”