Paper 2 Quantum Physics Drills

Q1 Photoelectric Effect

A metal has work function $2.30\mathrm{eV}$. Light of wavelength $410\mathrm{nm}$ is incident on it. Use $hc=1240\mathrm{eV}\mathrm{nm}$.

1. Calculate the photon energy in eV. [2]
2. Calculate the maximum kinetic energy of emitted photoelectrons in eV. [2]
3. Calculate the stopping potential. [1]
4. Explain the effect of increasing intensity at the same wavelength. [2]

Q2 Line Spectra

An electron in an atom falls from energy level $-1.50\mathrm{eV}$ to $-3.40\mathrm{eV}$.

1. Calculate the photon energy emitted. [2]
2. Calculate the photon wavelength. Use $hc=1240\mathrm{eV}\mathrm{nm}$. [2]
3. Explain why a line spectrum is observed rather than a continuous spectrum. [2]

Q3 X-ray Minimum Wavelength

Electrons are accelerated through $25.0\mathrm{kV}$ before hitting a metal target.

1. State the maximum possible X-ray photon energy in keV. [1]
2. Calculate the minimum wavelength. Use $hc=1240\mathrm{eV}\mathrm{nm}$. [2]
3. State how increasing tube current affects the spectrum. [2]