During a positron emission tomography (PET) scan, a positron and an electron, both assumed to have negligible initial kinetic energy, undergo annihilation. This process produces two identical, co-linear gamma-ray photons traveling in opposite directions.
What is the wavelength of each of the emitted gamma-ray photons?
(Use: Planck constant h=6.63×10−34 J sh = 6.63 \times 10^{-34}\text{ J s}h=6.63×10−34 J s, speed of light in a vacuum c=3.00×108 m s−1c = 3.00 \times 10^8\text{ m s}^{-1}c=3.00×108 m s−1, and electron rest mass me=9.11×10−31 kgm_e = 9.11 \times 10^{-31}\text{ kg}me=9.11×10−31 kg)
1.21×10−12 m1.21 \times 10^{-12}\text{ m}1.21×10−12 m
2.43×10−12 m2.43 \times 10^{-12}\text{ m}2.43×10−12 m
4.85×10−12 m4.85 \times 10^{-12}\text{ m}4.85×10−12 m
1.32×10−15 m1.32 \times 10^{-15}\text{ m}1.32×10−15 m
25 exam-style questions on OCR A A Level Physics Medical imaging, covering Using X-rays, Diagnostic methods in medicine, and Using ultrasound. Each one has a worked solution and a mark scheme showing where the marks go.