Waves

You will be able to

• Describe the difference between transverse and longitudinal waves in terms of the direction of vibration and the direction of energy transfer.
• Identify wavelength, amplitude, compressions and rarefactions on a wave.
• Calculate wave speed, frequency or wavelength using v = fλ.

You will be able to

• Describe reflection of plane water waves and show that the angle of incidence equals the angle of reflection.
• Explain refraction as a change of speed and wavelength at a boundary, with the frequency unchanged.
• Predict how the amount of diffraction depends on the gap width compared with the wavelength.

You will be able to

• Describe the law of reflection: the angle of incidence equals the angle of reflection, both measured from the normal.
• Determine the position of the image in a plane mirror using the rule image distance = object distance.
• Describe the image in a plane mirror as virtual, upright, the same size and laterally inverted.

You will be able to

• Calculate refractive index using n = sin i ÷ sin r.
• Determine the critical angle of a material using sin c = 1 ÷ n and describe total internal reflection.
• Describe the dispersion of white light by a prism and state which colour is refracted most.

You will be able to

• Draw ray diagrams for a thin converging lens using the three standard construction rays.
• Describe the image as real or virtual, upright or inverted, and magnified, diminished or the same size.
• Calculate linear magnification as image height ÷ object height.

You will be able to

• State the regions of the electromagnetic spectrum in order of wavelength and of frequency.
• Calculate the frequency of an electromagnetic wave using f = c ÷ λ with c = 3.0 × 10⁸ m/s.
• Describe one use and one hazard of each region and identify which regions are ionising.

You will be able to

• Describe how the pitch and loudness of a sound relate to frequency and amplitude on an oscilloscope trace.
• Calculate the speed of sound from an echo using v = 2d ÷ t.
• Explain why sound needs a medium and compare its speed in solids, liquids and gases.