Question

decrease the wavelength of the light. what is the maximum wavelength such that the emitted electrons can reach the collector plate (while the voltage remains set to -0.5v) ?

Answer 1

Te maximum wavelength for which the emitted electrons can reach the collector plate at a -0.5 V bias would be 400 nm.

The minimum energy required to eject an electron is given by:

hν ≥ Φ

where:

h is Planck's constant

ν is the light frequency

Φ is the work function of the metal

As the wavelength (λ) of the light decreases, its frequency (ν) and energy (hν) increase which means that with shorter wavelengths, more energy is available to eject electrons.

The minimum kinetic energy (KE_min) needed to reach the collector plate:

hν_max = Φ + KE_min

KE_min = e * V_bias

= e * (-0.5 V)

the metal in the experiment has a work function (Φ) = 3 eV.

hν_max = 3 eV + 8 x
`10^-^2^0`

ν_max = 7.5 x
`10^1^4` Hz

λ_max= c/ν_max

= 400 nm