Light of frequency produces a stopping potential of on a certain metal

PHYSICS · Subjective · A Level · Physics · Particles and radiation · Particles and radiation

Problem

Light of frequency

7.0\times10^{14}\,\text{Hz}

produces a stopping potential of

0.80\,\text{V}

on a certain metal. Light of frequency

9.0\times10^{14}\,\text{Hz}

produces a stopping potential of

2.1\,\text{V}

on the same metal. Determine the threshold frequency for this metal.