What does Eduqas fields and the universe cover?

It covers electrostatic and gravitational fields with Newton's law, Coulomb's law, field strength and potential, orbits and the wider universe with circular orbits, Kepler's third law and geostationary satellites, magnetic fields with flux density, F = BIL and F = Bqv, electromagnetic induction with flux linkage, Faraday's and Lenz's laws, using radiation to investigate stars with Wien's law and Stefan's law, and the expanding universe with redshift, Hubble's law and the Big Bang.

Which equations recur most across this content?

Newton's law $F = \frac{GMm}{r^2}$ and Coulomb's law $F = \frac{1}{4\pi\varepsilon_0}\frac{Q_1 Q_2}{r^2}$, field strengths $g = \frac{GM}{r^2}$ and $E = \frac{V}{d}$, the orbital relations $v = \sqrt{\frac{GM}{r}}$ and Kepler's $T^2 \propto r^3$, the magnetic forces $F = BIL$ and $F = Bqv$ with $r = \frac{mv}{Bq}$, Faraday's law $\varepsilon = \frac{\Delta(N\Phi)}{\Delta t}$, Wien's law $\lambda_\text{max} T = b$, Stefan's law $L = 4\pi R^2 \sigma T^4$, and Hubble's law $v = H_0 d$.

What is the most common mistake in this content?

Forgetting the negative sign on gravitational potential, or treating gravity as ever repulsive. Close behind are using the altitude rather than the orbital radius from the planet's centre, thinking a higher orbit is faster, getting Lenz's law backwards, forgetting the fourth power in Stefan's law, and confusing luminosity with the flux received at a distance.

How are orbits examined in Eduqas Physics?

Almost always by equating gravity to the centripetal force, $\frac{GMm}{r^2} = \frac{mv^2}{r}$, to find an orbital speed or period, then often applying Kepler's third law $T^2 = \frac{4\pi^2}{GM}r^3$ or analysing a geostationary orbit. The energy of an orbiting body and escape velocity also appear.

How should I revise fields and the universe?

Drill the inverse-square field calculations and the parallels between gravity and electrostatics. Master the orbit routine and Kepler's law, the magnetic force laws and circular motion of charges, and Faraday's and Lenz's laws. For astrophysics, practise Wien's law, Stefan's law and the inverse-square flux law, and the redshift and Hubble's law cosmology calculations.

EnglandPhysics

Eduqas A-Level Physics Fields and the universe: gravity, electric and magnetic fields, induction and cosmology

A deep-dive Eduqas A-Level Physics guide to the fields and astrophysics content across Components 2 and 3. Covers gravitational and electric fields, orbits and satellites, magnetic fields, electromagnetic induction, using radiation to investigate stars, and the expanding universe, with the calculations Eduqas repeats.

Generated by Claude Opus 4.817 min readA720QS Components 2 and 3Updated 2026-06-02

Reviewed by: AI editorial process; not yet individually human-reviewed

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What this module actually demands
Fields and orbits
Magnetism, induction and the cosmos
How this module is examined
Check your knowledge

What this module actually demands

The fields and astrophysics content draws together material from Component 2 (Electricity and the Universe) and Component 3 (Light, Nuclei and Options). It treats the inverse-square fields of gravity and electrostatics side by side, applies gravity to orbits and the universe, develops magnetic fields and electromagnetic induction, and uses the radiation from stars to probe the cosmos. The examiners reward fluent field calculations, the orbit routine, and clear physical reasoning about induction and cosmology.

This guide walks through the topics and sets out the exam patterns Eduqas repeats. Each topic has a matching dot-point page with practice; this overview ties them together.

Fields and orbits

Electrostatic and gravitational fields states Newton's law and Coulomb's law, recognises both as inverse-square laws, and defines field strength and potential for each, drawing out the parallels and the key difference (gravity only attracts). Orbits and satellites equates gravity to the centripetal force to analyse circular orbits, derives Kepler's third law, describes orbital energy, geostationary satellites and escape velocity.

Magnetism, induction and the cosmos

Magnetic fields defines flux density and uses $F = BIL$ and $F = Bqv$ , with the circular motion of charged particles $r = \frac{mv}{Bq}$ . Electromagnetic induction defines flux and flux linkage, states Faraday's and Lenz's laws, and describes generators and transformers. Using radiation to investigate stars applies black-body radiation, Wien's law and Stefan's law, and the inverse-square flux law. The expanding universe covers redshift, Hubble's law, the age of the universe and the evidence for the Big Bang.

How this module is examined

A typical Eduqas profile for this content:

Calculations. Field strength and force from the inverse-square laws, orbital speed and period, Kepler's law and geostationary radius, magnetic force and the radius of a charged particle's path, induced emf from Faraday's law, stellar temperature and luminosity, and redshift and Hubble's law.
Graph questions. Field and potential against distance, $T^2$ against $r^3$ , and black-body radiation curves.
Explanation and definition. The gravity-electrostatics parallel, geostationary conditions, Lenz's law and energy conservation, and the evidence for the Big Bang.
Extended answers. Orbital energy arguments, transformer and generator operation, and cosmological reasoning.

Check your knowledge

A mix of recall and calculation questions covering the module. Attempt them under timed conditions, then check against the solutions.

State Newton's law of gravitation. (1 mark)
A satellite orbits at radius $8.0 \times 10^{6}\ \text{m}$ around a planet of mass $6.0 \times 10^{24}\ \text{kg}$ . Find its orbital speed ( $G = 6.67 \times 10^{-11}$ ). (2 marks)
A wire of length $0.10\ \text{m}$ carries $3.0\ \text{A}$ perpendicular to a $0.20\ \text{T}$ field. Find the force on it. (2 marks)
State Faraday's law of electromagnetic induction. (1 mark)
A star's radiation peaks at $500\ \text{nm}$ . Find its surface temperature ( $b = 2.90 \times 10^{-3}\ \text{m K}$ ). (2 marks)
State Hubble's law. (1 mark)

Solutions

Q1: The gravitational force between two point masses is $F = \frac{GMm}{r^2}$ , attractive and along the line joining them.
Q2: $v = \sqrt{\frac{GM}{r}} = \sqrt{\frac{(6.67 \times 10^{-11})(6.0 \times 10^{24})}{8.0 \times 10^{6}}} = 7.1 \times 10^{3}\ \text{m s}^{-1}$ .
Q3: $F = BIL = 0.20 \times 3.0 \times 0.10 = 0.060\ \text{N}$ .
Q4: The induced emf is equal to the rate of change of flux linkage.
Q5: $T = \frac{b}{\lambda_\text{max}} = \frac{2.90 \times 10^{-3}}{500 \times 10^{-9}} = 5.8 \times 10^{3}\ \text{K}$ .
Q6: The recession speed of a galaxy is proportional to its distance, $v = H_0 d$ .

Sources & how we know this

Eduqas GCE AS/A Level Physics specification (A720QS) — WJEC Eduqas (2015)