Physics

Problem

Three samples of the same metal P, Q and R have work functions

2.5\,\text{eV}

3.0\,\text{eV}

and

4.2\,\text{eV}

respectively. Each sample is irradiated with ultraviolet light of frequency

1.1 \times 10^{15}\,\text{Hz}

at the same intensity. a. Rank the samples in descending order of the stopping potential developed between emitter and collector.