State how the behaviour of electromagnetic radiation at a substance depends on the radiation itself.

Whether the substance absorbs, transmits, refracts or reflects the radiation depends on the radiation's wavelength.

Explain why X-rays pass through flesh but are absorbed by bone.

The denser bone absorbs radiation of that wavelength strongly, while the softer tissue transmits most of it.

Suggest why a surface that looks black may still reflect infrared strongly.

Absorption varies with wavelength, so a surface can absorb visible light while reflecting the longer infrared waves.

Explain why the atmosphere lets visible light through but absorbs most of the ultraviolet from the Sun.

Gases such as ozone absorb the short ultraviolet wavelengths strongly while transmitting the longer visible ones.

Edexcel GCSE Combined Science Physics 1SC0

Key Concepts of Physics

Topic overview SI units in physics Multiples and sub-multiples of units Converting units, significant figures and standard form

Motion and Forces

Topic overview Scalar and vector quantities Examples of vectors and scalars, and velocity Speed, distance, time and distance-time graphs Acceleration and the equation v squared minus u squared Velocity-time graphs and free fall Measuring speed in the laboratory, and typical everyday speeds Newton's first law, and investigating force, mass and acceleration Newton's second and third laws Weight, mass and gravitational field strength Circular motion and centripetal force Inertial mass and momentum Collisions, and force as the rate of change of momentum Reaction time, stopping distance and large decelerations Factors affecting stopping distance and reaction time

Conservation of Energy

Topic overview Gravitational potential and kinetic energy Energy transfer diagrams and conservation of energy Energy stores and closed systems Dissipation and wasteful energy transfer Reducing unwanted energy transfer Efficiency and how to increase it Energy resources and trends in their use

Waves

Topic overview What waves transfer, and the evidence for it Frequency, wavelength, amplitude and period Longitudinal and transverse waves The wave equation Measuring wave speed, and what happens at a boundary Measuring waves in ripple tanks, strings and solids

Light and the Electromagnetic Spectrum

Topic overview Properties of electromagnetic waves Investigating refraction in glass blocks The groups of the electromagnetic spectrum The continuous spectrum, and what our eyes can detect Absorption, transmission and the velocity of electromagnetic waves How radiation is generated, and why danger rises with frequency Harmful effects of excessive exposure to radiation Uses of electromagnetic radiation

Radioactivity

Topic overview The atom and the size of atoms Isotopes, atomic number and mass number Relative masses and charges of subatomic particles Electron orbits and energy levels Forming ions, and how the atomic model changed Types of ionising radiation Background radiation and detecting radioactivity Alpha, beta and gamma, and their penetrating power Beta-minus and beta-plus decay Effects of decay on atomic number and mass number Balancing nuclear equations Activity and the becquerel Half-life and the randomness of decay Half-life calculations The dangers of ionising radiation Safety precautions, contamination and irradiation

Energy – Forces Doing Work

Topic overview Energy stores and energy transfer diagrams Changing a system's energy, and measuring work done Work done and the energy changes it causes Gravitational potential and kinetic energy calculations Dissipation and wasted energy Power as the rate of energy transfer The watt, and calculating efficiency

Forces and Their Effects

Topic overview Contact and non-contact forces Vectors and scalars, and reducing friction Resolving forces and free body diagrams Forces on an object in equilibrium

Electricity and Circuits

Magnetism and the Motor Effect

Topic overview Magnetic poles, permanent and induced magnets Uses of magnetic materials The magnetic field around a bar magnet Plotting compasses and the Earth's magnetic field The magnetic effect of an electric current Solenoids and electromagnets The motor effect and Fleming's left-hand rule The force on a conductor in a magnetic field

Electromagnetic Induction

Topic overview Factors affecting an induced potential difference How a transformer works The national grid, and step-up and step-down transformers Transformer power calculations

Particle Model

Topic overview Kinetic theory and differences in density Calculating density, and investigating it Changes of state and internal energy Specific heat capacity Specific latent heat and thermal insulation Investigating the specific heat capacity of water Gas pressure and the motion of particles Absolute zero and the kelvin scale

Forces and Matter

Topic overview Elastic and inelastic distortion Spring constant, and linear and non-linear behaviour Work done in stretching a spring

Light and the Electromagnetic Spectrum

Absorption, transmission and the velocity of electromagnetic waves

3 things to know
Paper 5

Overview

How absorption and transmission depend on wavelength in glass, oven doors, bone, black surfaces and the atmosphere, light slowing and refracting in glass and water, prisms splitting white light, and how radio waves are produced and received by an aerial.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Explain, in terms of oscillations, how a radio broadcast is produced, received by an aerial and turned into a current.

Key term

Explain why window glass is clear to visible light yet blocks much of the ultraviolet in sunlight.

Key term

Explain how the fine metal mesh in a microwave oven door keeps microwaves in while letting light out.

Questions from this subtopic

Each one with the model answer underneath.

1
State how the behaviour of electromagnetic radiation at a substance depends on the radiation itself.
Model answer
Whether the substance absorbs, transmits, refracts or reflects the radiation depends on the radiation's wavelength.
2
Explain why window glass is clear to visible light yet blocks much of the ultraviolet in sunlight.
Model answer
Glass transmits the longer visible wavelengths but absorbs the shorter ultraviolet ones.
3
Explain how the fine metal mesh in a microwave oven door keeps microwaves in while letting light out.
Model answer
The mesh reflects the long-wavelength microwaves, while the far shorter wavelengths of visible light pass through the holes.
4
Explain why X-rays pass through flesh but are absorbed by bone.
Model answer
The denser bone absorbs radiation of that wavelength strongly, while the softer tissue transmits most of it.
5
Suggest why a surface that looks black may still reflect infrared strongly.
Model answer
Absorption varies with wavelength, so a surface can absorb visible light while reflecting the longer infrared waves.
6
Explain why the atmosphere lets visible light through but absorbs most of the ultraviolet from the Sun.
Model answer
Gases such as ozone absorb the short ultraviolet wavelengths strongly while transmitting the longer visible ones.

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Key Concepts of Physics

Motion and Forces

Conservation of Energy

Waves

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