PhysicsQ&A by dot point

Electric current as the rate of flow of charge, the charge equation, potential difference as energy transferred per unit charge, resistance and the equation linking potential difference, current and resistance.

Electrical power and the two power equations, the energy transferred by a charge and by a device over time, and how to calculate the energy used and its cost using kilowatt-hours.

The I-V characteristics of an ohmic resistor, a filament lamp and a diode, ohmic and non-ohmic behaviour, and how the resistance of a thermistor and an LDR varies with temperature and light.

Circuit symbols and how to build circuits, the rules for current and potential difference in series and parallel circuits, and how total resistance changes when components are added in series or in parallel.

Charging insulators by friction through the transfer of electrons, attraction and repulsion between charges, electric fields around charges, and the uses and hazards of static electricity.

Efficiency as the fraction of energy usefully transferred, the efficiency equation, ways of reducing wasted energy, and the comparison of renewable and non-renewable energy resources with their trade-offs.

Energy stores (kinetic, gravitational, elastic, thermal, chemical, nuclear, magnetic, electrostatic), the four energy transfer pathways, the law of conservation of energy, and how energy is dissipated to the surroundings.

The national grid and the role of step-up and step-down transformers, why transmission is at high voltage and low current, the transformer turns and power relationships, and the nature of mains electricity as an alternating supply.

The structure of the Solar System, the life cycle of stars, red-shift of light from distant galaxies, and how red-shift provides evidence for an expanding universe and the Big Bang theory.

Stopping distance as thinking distance plus braking distance, the factors that affect each, the energy and force involved in braking, and how safety features reduce the force on occupants by increasing the collision time.

Work done as energy transferred by a force, the work done equation, the kinetic energy and gravitational potential energy equations, and power as the rate of doing work or transferring energy.

Elastic and inelastic deformation, Hooke's law and the force on a spring, the limit of proportionality, the energy stored in a stretched spring, and the force-extension practical.

The moment of a force as a turning effect, the principle of moments for a balanced object, levers and gears as force multipliers, and applications such as spanners and seesaws.

Momentum as mass times velocity, the conservation of momentum in collisions and explosions, force as the rate of change of momentum, and how safety features increase collision time to reduce force.

Scalar and vector quantities, distance, displacement, speed, velocity and acceleration, distance-time and velocity-time graphs, the meaning of gradient and area under a graph, and the SUVAT equation for uniform acceleration.

Newton's three laws of motion, resultant force, the difference between mass and weight, the equations for weight and resultant force, friction and drag, and terminal velocity.

The magnetic field around a current-carrying wire and a solenoid, electromagnets and what affects their strength, the motor effect, Fleming's left-hand rule, and the electric motor.

Electromagnetic induction and the generator effect, the factors that affect the induced potential difference, how a generator produces a.c., and how step-up and step-down transformers change the voltage.

Permanent and induced magnets, magnetic materials, attraction and repulsion between poles, the magnetic field around a bar magnet and the Earth, and how a compass shows field direction.

Changes of state (melting, freezing, boiling, evaporating, condensing and sublimation) explained by the particle model, heating and cooling curves, conservation of mass, and the difference between physical and chemical changes.

Internal energy as the total kinetic and potential energy of the particles, specific heat capacity and the equation linking energy, mass and temperature change, and specific latent heat for changes of state.

The particle model of the three states of matter, the arrangement and motion of particles in solids, liquids and gases, and density as mass per unit volume, including measuring the density of regular and irregular objects.

Gas pressure as the result of particle collisions, the effect of temperature and volume on gas pressure, pressure in liquids increasing with depth, the pressure due to a column of liquid, and pressure on a surface.

The structure of the atom in terms of protons, neutrons and electrons, atomic number and mass number, isotopes, the size and charge of the nucleus, and how the nuclear model replaced the plum pudding model.

The nature and properties of alpha, beta and gamma radiation, their ionising and penetrating power, and writing balanced nuclear equations for alpha decay, beta-minus decay and gamma emission, conserving mass number and atomic number.

Nuclear fission as the splitting of a large unstable nucleus, the chain reaction in a reactor and its control, nuclear fusion as the joining of two light nuclei, and why fusion needs extremely high temperatures and pressures.

Radioactive decay as a random process, activity and count rate, the meaning of half-life, and calculating half-life or the time for a given decay from a graph or table of count rate.

The uses of radioactive sources (medical tracers, treating cancer, sterilisation, smoke alarms and thickness control), the difference between irradiation and contamination, the hazards of ionising radiation, and how exposure is reduced.

The reflection of waves and the law of reflection, the refraction of waves at a boundary and why it happens, total internal reflection, and how converging and diverging lenses form images.

Sound as a longitudinal wave, how sound travels through a medium and is heard, the human hearing range, ultrasound and its uses in imaging and measuring distance, and echoes.

The electromagnetic spectrum from radio to gamma, its order by wavelength, frequency and energy, the common properties of all electromagnetic waves, and the uses and hazards of each part.

Transverse and longitudinal waves, the wave quantities (amplitude, wavelength, frequency and period), the wave speed equation, the relationship between frequency and period, and the waves practical.