A metallic plate exposed to white light emits electrons. The colour of light for which the stopping potential will be minimum is

Orange

The correct answer is Option (2) → Orange

Given: A metallic plate emits electrons when exposed to white light.

Relation: $eV_0 = hν - φ$

The stopping potential $V_0$ increases with frequency $ν$ of the incident light.

Hence, the minimum stopping potential corresponds to the lowest frequency (or longest wavelength) among the given colours.

Order of frequency: Red < Orange < Green < Blue < Indigo

Therefore, among the given options, Orange light has the lowest frequency and gives the minimum stopping potential.

Answer: Orange