Calculate the maximum kinetic energy of photoelectrons emitted from this plate when light of wavelength (λ) 520nm is directed at the metal surface.

Work function (Ф) of the plate = 1.1 * 10⁻¹⁹ J

Planck's constant (h) = 6.63 * 10⁻³⁴ Js

Frequency (f) = c : λ

c = speed light in vacuum = 3.00 * 10⁸ms⁻¹

Ekmax = hf - Φ

Wavelength must be in metres, so it'll be 590*10⁻⁹

I've worked this out and gotten two different answers so I thought I'd check to see which one is right.

Question

Physics

Macey Preston

2 August, 16:31

Calculate the maximum kinetic energy of photoelectrons emitted from this plate when light of wavelength (λ) 520nm is directed at the metal surface.

Work function (Ф) of the plate = 1.1 * 10⁻¹⁹ J

Planck's constant (h) = 6.63 * 10⁻³⁴ Js

Frequency (f) = c : λ

c = speed light in vacuum = 3.00 * 10⁸ms⁻¹

Ekmax = hf - Φ

Wavelength must be in metres, so it'll be 590*10⁻⁹

I've worked this out and gotten two different answers so I thought I'd check to see which one is right.

+2

Answers (1)

Know the Answer?

Malcolm Mccann · Answer 1

Well for a start, 520nm is 520 nanometres and for some reason you've called it 590 x10^-9 (590 isn't standard form) where it's actually 5.2 * 10^-7 metres.

Put that into the equations:

f = c/λ = 3.0 x10^8/5.2 * 10^-7 = 5.77 x10^14 (3 s. f.)

(5.77 x10^14) x (6.63 x10^-34) - (1.1 x10^-19) =

2.73 x10^-19 J