Radiation and waves

• Understand the model of radiation where a source emits energy that spreads out and transfers to an absorber. • Identify light as one member of the electromagnetic spectrum family, all of which travel at the same speed through space. • Describe the interaction of radiation with objects, including transmission, reflection, and absorption. • Explain that absorption of radiation typically causes heating, while high-energy radiation (X-rays, gamma rays, UV) causes ionisation. • Analyze the risks of ionising radiation to living cells, including uncontrolled growth and cancer. • Explain the role of ozone in the upper atmosphere in absorbing harmful ultraviolet radiation. • Describe how radio waves are produced by and detected using oscillating electrical currents. • Evaluate the uses of different parts of the electromagnetic spectrum based on their transmission, reflection, and absorption properties. • Assess the risks and benefits of technologies utilizing the electromagnetic spectrum.

• Explain the relationship between the temperature of an object and the principal frequency of its emitted electromagnetic radiation. • Describe the greenhouse effect, including the transmission of solar radiation, absorption by the Earth, and re-emission at lower frequencies absorbed by atmospheric gases. • Identify carbon dioxide, methane, and water vapour as greenhouse gases. • Analyze the correlation between rising atmospheric carbon dioxide levels and human activities such as fossil fuel combustion and deforestation. • Evaluate the evidence for human-induced global warming provided by computer climate models.

• Define a wave as a regular disturbance transferring energy without transferring matter. • Distinguish between transverse waves (disturbance perpendicular to motion) and longitudinal waves (disturbance parallel to motion). • Define wave speed, frequency, and wavelength. • Model the reflection and refraction of light and sound using water waves. • Explain refraction as a change in wave speed leading to a change in wavelength and direction when passing into a different medium.

• Describe specular reflection from smooth surfaces and scattering from uneven surfaces. • Explain refraction and dispersion in prisms using the wave model. • Explain colour perception in terms of differential reflection, absorption, and transmission of wavelengths. • Describe the transmission of sound through solids and the function of the ear bones. • Explain the principles of ultrasound imaging, seismic exploration, and SONAR based on wave transmission, reflection, and refraction.