IB Physics E.2 Quantum Physics Questionbank

In an experiment, light of increasing intensity but fixed frequency below the threshold frequency is shone on a metal surface. What is observed?

Which quantity is directly proportional to the energy of a photon?

A beam of electrons is accelerated through a potential difference of $150\ \text{V}$. The electrons then pass through a narrow slit producing a diffraction pattern on a screen.

(b) Explain why the observation of diffraction patterns from electrons demonstrates wave–particle duality.

(c) Describe how increasing the accelerating voltage affects the diffraction pattern.

$\mathrm{J\cdot s}$

$\mathrm{N \cdot m}$

$\mathrm{eV}$

$\mathrm{kg \cdot m \cdot s}^{-1}$

Double-slit experiment

Blackbody radiation

Photoelectric effect

Electron diffraction

(a) Calculate the de Broglie wavelength of the electrons. (Electron mass $m_e = 9.11 \times 10^{-31}\ \text{kg}$, charge $e=1.60 \times 10^{-19}\ \text{C}$, Planck constant $h=6.63 \times 10^{-34}\ \text{J s}$.)