Answer:
work function = 3 eV
Explanation:
given,
Energy of photon = 7 eV
electrical potential = 4 V
Work function = ?
using equation,
energy of photon = work function + qVs
work function = energy of photon - qVs
work function = 7 eV - 4 eV
work function = 3 eV
Hence, work function of the metal is equal to 3 eV