A bulb of 60W in a classroom remains switched on for a long time from 9 am to 5 pm due to the negligence of students in the class
Calculate in joule the electric energy consumed by the bulb ?

A bulb of 60W in a classroom remains switched on for a long time from 9 am to 5 pm due to the negligence of students in the class If similar negligence had happened in 3 clasrooms, how many units of electric energy would have been wasted ?

A photon of wave length 400 nm strikes a metal surface. The electrons are ejected with a velocity 5.85 xx 10^5 ms^(-1) . Calculate the minimum energy required to remove an electron from the metal surface. The mass of an electron is 9.109 xx 10^-(31) kg_.