Unit 2: Waves and Electricity

2.3.33Wave quantities

Understand the terms amplitude, frequency, period, speed and wavelength

2.3.34Wave equation

Be able to use the wave equation v = fλ

2.3.35Longitudinal waves

Be able to describe longitudinal waves in terms of pressure variation and the displacement of molecules

2.3.36Transverse waves

Be able to describe transverse waves

2.3.37Wave graphs

Be able to draw and interpret graphs representing transverse and longitudinal waves including standing/stationary waves

2.3.38Core Practical 4 - speed of sound in air

CORE PRACTICAL 4: Determine the speed of sound in air using a 2-beam oscilloscope, signal generator, speaker and microphone

2.3.39Wavefronts, coherence and interference

Know and understand what is meant by wavefront, coherence, path difference, superposition, interference and phase

2.3.40Phase difference and path difference

Be able to use the relationship between phase difference and path difference

2.3.41Standing waves, nodes and antinodes

Know what is meant by a standing or stationary wave, understand how it is formed, and identify nodes and antinodes.

2.3.42Speed of a transverse wave on a string

Use v = √(T/μ) for the speed of a transverse wave on a string.

2.3.43Core Practical 5 - vibrating string frequency

CORE PRACTICAL 5: Investigate how length, tension and mass per unit length affect the frequency of a vibrating string or wire.

2.3.44Intensity of radiation

Use I = P/A for the intensity of radiation.

2.3.45Refraction at a boundary

Use n1 sin θ1 = n2 sin θ2 at a boundary between two media and refractive index n = c/v.

2.3.46Critical angle

Calculate critical angle using sin C = 1/n.

2.3.47Total internal reflection

Be able to predict whether total internal reflection will occur at an interface

2.3.48Measuring refractive index

Understand how to measure the refractive index of a solid material

2.3.49Plane polarisation

Understand what is meant by plane polarisation

2.3.50Diffraction and Huygens’ construction

Understand what is meant by diffraction and use Huygens’ construction to explain what happens to a wave when it meets a slit or an obstacle

2.3.51Diffraction grating equation

Be able to use nλ = dsinθ for a diffraction grating

2.3.52Core Practical 6 - wavelength using diffraction grating

CORE PRACTICAL 6: Determine the wavelength of light from a laser or other light source using a diffraction grating

2.3.53Electron diffraction evidence

Understand how diffraction experiments provide evidence for the wave nature of electrons

2.3.54De Broglie wavelength

Use the de Broglie equation λ = h/p.

2.3.55Transmission and reflection at boundaries

Understand that waves can be transmitted and reflected at an interface between media

2.3.56Pulse-echo techniques

Understand how a pulse-echo technique can provide information about the position of an object and how the amount of information obtained may be limited by the wavelength of the radiation or by the duration of pulses

2.3.57Wave and photon models of EM radiation

Understand how the behaviour of electromagnetic radiation can be described in terms of a wave model and a photon model, and how these models developed over time

2.3.58Photon energy

Be able to use the equation E = hf, that relates the photon energy to the wave frequency

2.3.59Photon absorption and photoelectron emission

Understand that the absorption of a photon can result in the emission of a photoelectron

2.3.60Threshold frequency and work function

Understand threshold frequency and work function and use the photoelectric equation hf = φ + ½mvmax².

2.3.61Electronvolt

Be able to use the electronvolt (eV) to express small energies

2.3.62Photoelectric effect evidence

Understand how the photoelectric effect provides evidence for the particle nature of electromagnetic radiation

2.3.63Atomic line spectra and energy levels

Understand atomic line spectra in terms of transitions between discrete energy levels and understand how to calculate the frequency of radiation that could be emitted or absorbed in a transition between energy levels.

Understand current as the rate of flow of charge and use I = ΔQ/Δt.

Use potential difference V = W/Q.

Understand resistance R = V/I and Ohm's law as the special case I ∝ V at constant temperature.

(a) understand how the distribution of current in a circuit is a consequence of charge conservation (b) understand how the distribution of potential differences in a circuit is a consequence of energy conservation

Be able to derive the equations for combining resistances in series and parallel using the principles of charge and energy conservation, and be able to use these equations

Use P = VI and W = VIt, and derive and use P = I²R and P = V²/R.

Sketch, recognise and interpret current–potential-difference graphs for ohmic conductors, filament bulbs, thermistors and diodes.

Use R = ρl/A for the resistance of a uniform conductor.

CORE PRACTICAL 7: Determine the electrical resistivity of a material

Be able to use I = nqvA to explain the large range of resistivities of different materials

Understand how the potential along a uniform current-carrying wire varies with the distance along it

Understand the principles of a potential divider circuit and understand how to calculate potential differences and resistances in such a circuit

Be able to analyse potential divider circuits where one resistance is variable including thermistors and light dependent resistors (LDRs)

Know the definition of electromotive force (e.m.f.) and understand what is meant by internal resistance and know how to distinguish between e.m.f. and terminal potential difference

CORE PRACTICAL 8: Determine the e.m.f. and internal resistance of an electrical cell

Understand how changes of resistance with temperature may be modelled in terms of lattice vibrations and number of conduction electrons and understand how to apply this model to metallic conductors and negative temperature coefficient thermistors

Understand how changes of resistance with illumination may be modelled in terms of the number of conduction electrons and understand how to apply this model to LDRs.