Gamma rays are directed at a tumour from four directions. Each beam delivers 3 dose units to the tumour and 3 dose units to healthy tissue along its path. The four paths overlap only at the tumour. A single beam would deliver 12 dose units to the tumour and to healthy tissue along its path. Which statement explains the advantage of using four directions?
The tumour receives only 3 units; each healthy path receives 12 units.
The tumour still receives 12 units; each healthy path receives 12 units.
The tumour still receives 12 units; each healthy path receives 3 units.
The tumour receives only 3 units; each healthy path receives 3 units.
104 exam-style questions on Edexcel GCSE Physics 5.4 Uses and dangers of EM radiation, covering 5.4.1 Dangers of electromagnetic radiation, 5.4.2 Uses of electromagnetic radiation, 5.4.3 Radio waves and oscillations in circuits, and 5.4.4 Changes in atoms and nuclei generating radiation. Each one has a worked solution and a mark scheme showing where the marks go.