According to wave theory, after the light falls on a substance electrons are emitted after a small instant of time. However, in photoelectric effect, the electron emissions are immediate without a time delay. ​The energy of a wave increases with increase in intensity. However, in photoelectirc effect, increase in intensity has no effect on the energy of electrons emitted. All that happens is the number of electrons emitted, increases.he energy of a wave grows as its intensity increases. In the photoelectronic effect, however, increasing the intensity has no influence on the energy of electrons released.