levo

Radioactivity

Nuclear fusion and how it differs from fission

  • 2 things to know
  • Paper 1

Overview

What fusion is, why joining small nuclei releases energy from lost mass, hydrogen fusing to helium in the Sun, and how fusion compares with fission in use, waste and temperature.

What you need to know

Answer each one before you reveal it.

Your recallNot started
Key term

What is nuclear fusion?

Key term

Why does the joining of two small nuclei release energy?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What is nuclear fusion?

    Model answer

    Nuclear fusion is the joining together of two small nuclei to make a single larger nucleus.

  2. 2

    Why does the joining of two small nuclei release energy?

    Model answer

    The nucleus formed has slightly less mass than the two nuclei that made it, and the lost mass is released as energy.

  3. 3

    Which process is the energy source of the Sun and of other stars?

    Model answer

    Nuclear fusion.

  4. 4

    Which nuclei fuse together in the core of the Sun, and what do they form?

    Model answer

    Hydrogen nuclei fuse together to form helium.

  5. 5

    Why is the total mass after a fusion reaction less than the total mass before it?

    Model answer

    Some of the mass has been released as energy.

  6. 6

    Does the fusion of two small nuclei release energy or absorb it?

    Model answer

    It releases energy.

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.

1Closed book
2Open book
3Closed book

The 3-step method, run for you

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

Key Concepts of Physics
Motion and Forces
Conservation of Energy
Waves

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

2.5 × = 9000 s.
360027001000

Blank Blitz makes facts automatic

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

ALength is measured in metres, with the symbol m.
BMass is measured in kilograms, symbol kg.
CTime is measured in seconds, symbol s.

Build It gets the exam shape right

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

Watt means the unit of power, symbol W.
TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Every question in Radioactivity, on a schedule.

Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.

Or £46 a year, about £3.83 a month. Cancel anytime.