A stream of photons having energy 3 eV each impinges on a potassium surface. The work
Channel: Doubtnut
Date: 2020-08-23

A stream of photons having energy 3 eV each impinges on a potassium surface. The work function of potassium is  2.3 eV. The emerging photo-electrons are slowed down by a copper plate placed 5 mm away. If the potential  difference between the two metal plates is 1 V, the maximum distance the electrons can move away from the  potassium surface before being turned back is–