Does the equation E = mc² apply only to nuclear reactions, or does it apply more broadly?

E = mc² applies to all energy changes, not just nuclear reactions. Any change in energy corresponds to a change in mass, though the mass change is usually negligible for non-nuclear processes.

State the formula that relates energy and mass in Einstein's mass-energy equivalence.

E = mc², where E is energy, m is mass, and c is the speed of light in a vacuum.

What is mass defect (mass difference)?

Mass defect is the difference between the total mass of the separate nucleons and the mass of the nucleus they form.

Why is the mass of a nucleus less than the sum of the masses of its individual protons and neutrons?

Some mass is converted to binding energy when the nucleons bind together, so the nucleus has less mass than the separate nucleons.

Define binding energy of a nucleus.

Binding energy is the energy equivalent of the mass defect, representing the energy released when separate nucleons bind together to form a nucleus.

What does the binding energy of a nucleus represent in terms of nuclear stability?

It represents the energy that would need to be supplied to completely separate the nucleus into its individual nucleons, indicating how tightly bound the nucleus is.

AQA A-Level Physics 7408

Measurements and Their Errors

Topic overview Use of SI units and their prefixes Limitation of physical measurements Estimation of physical quantities

Particles and Radiation

Topic overview Constituents of the atom Stable and unstable nuclei Particles, antiparticles and photons Particle interactions Classification of particles Quarks and antiquarks Applications of conservation laws The photoelectric effect Collisions of electrons with atoms Energy levels and photon emission Wave-particle duality

Waves

Topic overview Progressive waves Longitudinal and transverse waves Principle of superposition of waves and formation of stationary waves Interference Diffraction Refraction at a plane surface

Mechanics and Materials

Topic overview Scalars and vectors Moments Motion along a straight line Projectile motion Newton's laws of motion Momentum Work, energy and power Conservation of energy Bulk properties of solids The Young modulus

Electricity

Topic overview Basics of electricity Current–voltage characteristics Resistivity Circuits Potential divider Electromotive force and internal resistance

Further Mechanics and Thermal Physics

Topic overview Circular motion Simple harmonic motion (SHM)Simple harmonic systems Forced vibrations and resonance Thermal energy transfer Ideal gases Molecular kinetic theory model

Fields and Their Consequences

Topic overview Fields Newton's law Gravitational field strength Gravitational potential Orbits of planets and satellites Coulomb's law Electric field strength Electric potential Capacitance Parallel plate capacitor Energy stored by a capacitor Capacitor charge and discharge Magnetic flux density Moving charges in a magnetic field Magnetic flux and flux linkage Electromagnetic induction Alternating currents Transformers

Nuclear Physics

Topic overview Rutherford scattering α, β and γ radiation Radioactive decay Nuclear instability Nuclear radius Mass and energy Induced fission Safety aspects

AstrophysicsOptional topic

Topic overview Astronomical telescope consisting of two converging lenses Reflecting telescopes Single dish radio telescopes, I-R, U-V and X-ray telescopes Advantages of large diameter telescopes Classification by luminosity Absolute magnitude, M Classification by temperature, black-body radiation Principles of the use of stellar spectral classes The Hertzsprung-Russell (HR) diagram Supernovae, neutron stars and black holes Doppler effect Hubble's law Quasars Detection of exoplanets

Medical PhysicsOptional topic

Engineering PhysicsOptional topic

Topic overview Concept of moment of inertia Rotational kinetic energy Rotational motion Torque and angular acceleration Angular momentum Work and power First law of thermodynamics Non-flow processes The p–V diagram Engine cycles Second Law and engines Reversed heat engines

Turning Points in PhysicsOptional topic

Topic overview Cathode rays Thermionic emission of electrons Specific charge of the electron Principle of Millikan's determination of the electronic charge, e Newton's corpuscular theory of light Significance of Young's double slits experiment Electromagnetic waves The discovery of photoelectricity Wave–particle duality Electron microscopes The Michelson-Morley experiment Einstein's theory of special relativity Time dilation Length contraction Relativistic mass and energy

ElectronicsOptional topic

Topic overview MOSFET (metal-oxide semiconducting field-effect transistor)Zener diode Photodiode Hall effect sensor Difference between analogue and digital signals LC resonance filters The ideal operational amplifier Inverting amplifier configuration Non-inverting amplifier configuration Summing amplifier configuration Real operational amplifiers Combinational logic Sequential logic Astables Principles of communication systems Transmission media Time-division multiplexing Amplitude (AM) and frequency modulation (FM) techniques

Nuclear Physics

Mass and energy

5 things to know
Papers 2 and 3

Overview

E = mc², mass defect and binding energy, the atomic mass unit, and calculating energy released.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Numbers

What is Einstein's mass-energy relation, and does it apply beyond nuclear reactions?

Numbers

How is the atomic mass unit defined, and what is its energy equivalent?

Numbers

How is a mass defect converted to energy, and what are fission and fusion?

Numbers

How is the energy released in a nuclear reaction calculated from the mass difference?

Numbers

What steps convert reactant and product masses into an energy release?

Questions from this subtopic

Each one with the model answer underneath.

1
Does the equation E = mc² apply only to nuclear reactions, or does it apply more broadly?
Model answer
E = mc² applies to all energy changes, not just nuclear reactions. Any change in energy corresponds to a change in mass, though the mass change is usually negligible for non-nuclear processes.
2
State the formula that relates energy and mass in Einstein's mass-energy equivalence.
Model answer
E = mc², where E is energy, m is mass, and c is the speed of light in a vacuum.
3
What is mass defect (mass difference)?
Model answer
Mass defect is the difference between the total mass of the separate nucleons and the mass of the nucleus they form.
4
Why is the mass of a nucleus less than the sum of the masses of its individual protons and neutrons?
Model answer
Some mass is converted to binding energy when the nucleons bind together, so the nucleus has less mass than the separate nucleons.
5
Define binding energy of a nucleus.
Model answer
Binding energy is the energy equivalent of the mass defect, representing the energy released when separate nucleons bind together to form a nucleus.
6
What does the binding energy of a nucleus represent in terms of nuclear stability?
Model answer
It represents the energy that would need to be supplied to completely separate the nucleus into its individual nucleons, indicating how tightly bound the nucleus is.

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