State what the de Broglie wavelength means.
Calculate the de Broglie wavelength for an electron travelling at a speed of $4.9 \times 10^{7}\,\text{m s}^{-1}$.
State one similarity and one difference between an electron and a positron.
An electron travelling at a speed of $4.9 \times 10^{7}\,\text{m s}^{-1}$ collides with a positron moving at the same speed in the opposite direction. Two gamma-ray photons are then produced. State the name of this type of reaction.
State what occurs to the electron and to the positron.
Explain why two gamma-ray photons are produced instead of only one.
Show that the electron’s kinetic energy before the collision is $1.1 \times 10^{-15}\,\text{J}$.
Use the information in d(iv) to find, to three significant figures, the wavelength linked to the gamma radiation emitted in the collision.