5.2.1
Radioactivity
Radioactivity
Radioactivity
An atom can have an unstable nucleus. An unstable nucleus can become more stable over time by randomly and spontaneously emitting ionising radiation. This process is called radioactive decay.


Radioactive substances
Radioactive substances
- Substances that decay radioactively are “radioactive substances”.


Decay is random and spontaneous
Decay is random and spontaneous
- Being random means that we cannot predict when an individual atom will emit (produce) ionising radiation.
- The direction of emission is random.
- Being spontaneous means that the process happens on its own, without any outside cause or trigger.
1Motion, Forces & Energy
1.1Physical Quantities & Measurement Techniques
1.2Motion
1.2.1Average Speed
1.2.2Calculating Average Speed
1.2.3Velocity
1.2.4Acceleration
1.2.5Distance-Time Graphs
1.2.6Speed-Time Graphs
1.2.7More Speed-Time Graphs
1.2.8Calculating Uniform Acceleration
1.2.9Gravity
1.2.10Free Fall - Distance-Time & Speed-Time Graphs
1.2.11Air Resistance
1.2.12Air Resistance - Graphs
1.2.13Optional: Calculating Acceleration
1.3Mass & Weight
1.5Forces: Effects of Forces
1.6Forces: Turning Effects of Forces
1.7Forces: Centre of Gravity
1.8Momentum
1.9Energy, Work, & Power: Energy
1.10Energy, Work & Power: Work
1.11Energy, Work & Power: Energy Resources
1.12Energy, Work & Power: Power
2Thermal Physics
2.1Kinetic Particle Model of Matter
2.2Thermal Properties & Temperature
3Waves
3.1General Properties of Waves
3.2Light: Reflection & Refraction
3.3Light: Thin Lenses
3.4Light: Dispersion of Light
3.5Electromagnetic Spectrum
4Electricity & Magnetism
4.1Simple Phenomena of Magnetism
4.2Electrical Quantities: Electric Charge
4.3Electrical Quantities: Electric Current
4.4Electromotive Force & Potential Difference
4.5Electrical Quantities: Resistance
4.6Electrical Energy & Electrical Power
4.7Electric Circuits: Circuit Diagrams & Components
4.8Electric Circuits: Series & Parallel Circuits
4.9Electric Circuits: Action & Use
4.10Electrical Safety
4.11Electromagnetic Effects: Electromagnetic Induction
4.12Electromagnetic Effects: The A.C. Generator
4.13Magnetic Effect of a Current
4.14Force on a Current-Carrying Conductor
4.15Electromagnetic Effects: The D.C. Motor
4.16Electromagnetic Effects: The Transformer
5Nuclear Physics
5.1The Nuclear Model of the Atom
5.2Radioactivity: Detection of Radioactivity
5.3Radioactivity: The Three Types of Nuclear Emission
6Space Physics
6.1The Earth & the Solar System
Jump to other topics
1Motion, Forces & Energy
1.1Physical Quantities & Measurement Techniques
1.2Motion
1.2.1Average Speed
1.2.2Calculating Average Speed
1.2.3Velocity
1.2.4Acceleration
1.2.5Distance-Time Graphs
1.2.6Speed-Time Graphs
1.2.7More Speed-Time Graphs
1.2.8Calculating Uniform Acceleration
1.2.9Gravity
1.2.10Free Fall - Distance-Time & Speed-Time Graphs
1.2.11Air Resistance
1.2.12Air Resistance - Graphs
1.2.13Optional: Calculating Acceleration
1.3Mass & Weight
1.5Forces: Effects of Forces
1.6Forces: Turning Effects of Forces
1.7Forces: Centre of Gravity
1.8Momentum
1.9Energy, Work, & Power: Energy
1.10Energy, Work & Power: Work
1.11Energy, Work & Power: Energy Resources
1.12Energy, Work & Power: Power
2Thermal Physics
2.1Kinetic Particle Model of Matter
2.2Thermal Properties & Temperature
3Waves
3.1General Properties of Waves
3.2Light: Reflection & Refraction
3.3Light: Thin Lenses
3.4Light: Dispersion of Light
3.5Electromagnetic Spectrum
4Electricity & Magnetism
4.1Simple Phenomena of Magnetism
4.2Electrical Quantities: Electric Charge
4.3Electrical Quantities: Electric Current
4.4Electromotive Force & Potential Difference
4.5Electrical Quantities: Resistance
4.6Electrical Energy & Electrical Power
4.7Electric Circuits: Circuit Diagrams & Components
4.8Electric Circuits: Series & Parallel Circuits
4.9Electric Circuits: Action & Use
4.10Electrical Safety
4.11Electromagnetic Effects: Electromagnetic Induction
4.12Electromagnetic Effects: The A.C. Generator
4.13Magnetic Effect of a Current
4.14Force on a Current-Carrying Conductor
4.15Electromagnetic Effects: The D.C. Motor
4.16Electromagnetic Effects: The Transformer
5Nuclear Physics
5.1The Nuclear Model of the Atom
5.2Radioactivity: Detection of Radioactivity
5.3Radioactivity: The Three Types of Nuclear Emission
6Space Physics
6.1The Earth & the Solar System
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