The Universe

Red-shift

Light from distant objects in space becomes shifted towards the red end of the spectrum. This effect is called red-shift.

Red-shift

As an object moves away from us, the wavelength of light that the object emits (sends out) gets longer.
The light gets redder because red has the longest wavelength of the visible colours.
This effect is called red-shift.
The faster the object is moving away from us, the longer its wavelength gets and the redder it appears.

Evidence for an expanding universe

Light from distant galaxies in space is red-shifted.
The further a galaxy is from Earth, the greater the red-shift.
- This means that the further away a galaxy is, the faster it is moving away from us.
This is evidence that the universe is expanding.

The Big Bang

The Big Bang theory says that the universe began from a single point.

The Big Bang

The universe began from a very small region that was hot and dense.
This region ‘exploded’ and started expanding.
This expansion is still happening.

Evidence

There are many forms of evidence to support the Big Bang model of the universe.
An example is the observation of red-shift in distant galaxies.
- This suggests that the universe has expanded from a single point and continues to expand today.

Gaps in Knowledge

Although science can explain so much of what we see in the universe, there is still a lot we cannot currently explain.

How expansion happens

Scientists still don’t understand everything about the universe.
They don’t understand much about how the universe is expanding.

Dark matter and dark energy

Some scientists think that the universe is mostly made up of dark matter (an unknown substance that holds galaxies together but doesn’t emit electromagnetic radiation) and dark energy (the thing that causes the universe to quickly expand).
But no one really knows what these are - they are just theories.

1Energy

2Electricity

3Particle Model of Matter

3.1States of Matter

3.1.1Atomic Structure

3.1.2Atomic Structure 2

3.1.3Density

3.1.4Density - Calculations

3.1.5Changes of State

3.1.6Exam-Style Questions - Density

3.2Heat

3.2.1Internal Energy

3.2.2Heat Capacities

3.2.3Internal Energy - Calculations

3.2.4Latent Heat

3.2.5Latent Heat - Calculations

3.2.6Latent Heat Experiments

3.3Particle Motion in Gases

3.3.1Particle Motion in Gases

3.3.2Particle Motion in Gases 2

3.3.3End of Topic Test - Particle Model of Matter

3.3.4Grade 9 - Particle Model of Matter

3.3.5Exam-Style Questions - Specific Heat Capacity

4Atoms & Radiation

4.1Atoms

4.1.1Atomic Model

4.1.2Atomic Model 2

4.1.3Atoms & Ions

4.1.4Isotopes

4.1.5Exam-Style Questions - Atomic Structure

4.2Radiation

4.2.1Radioactive Decay

4.2.2Radioactive Decay 2

4.2.3Types of Radioactive Emission

4.2.4Fission & Fusion

4.2.5Radioactive Decay Equations

4.2.6Radio. decay equations - Calculations

4.2.7Half Lives & Ionising Radiation

4.2.8Half Life - Calculations

4.2.9Uses & Dangers of Radiation

4.2.10Uses & Dangers of Radiation 2

4.2.11End of Topic Test - Atoms & Radiation

4.2.12Grade 9 - Radiation

4.2.13Exam-Style Questions - Radioactive Decay

5Forces

5.1Basics of Motion

5.1.1Basics of Motion

5.1.2Basics of Motion 2

5.1.3Basics of Motion 3

5.1.4Distance- & Speed-Time Graphs

5.1.5Average Speed - Calculations

5.1.6Acceleration - Calculations

5.1.7Uniform Acceleration - Calculations

5.1.8Grade 9 - Motion

5.1.9Exam-Style Questions - Motion

5.2Forces

5.2.1Gravity

5.2.2Gravity - Calculations

5.2.3Resultant Forces

5.2.4Newton Second Law - Calculations

5.2.5Force Diagrams

5.2.6Free Body Diagrams - Calculations

5.2.7Stretching a Spring

5.2.8Hooke's Law

5.2.9Hooke's Law - Calculations

5.2.10Elastic Potential Energy

5.2.11Elastic Potential - Calculations

5.2.12Exam-Style Questions - Elastic Potential Energy

5.3Effects of Forces

5.3.1Acceleration

5.3.2Acceleration 2

5.3.3Momentum

5.3.4Change in Momentum - Calculations

5.3.5Momentum - Calculations

5.3.6Moments

5.3.7Moments - Calculations

5.3.8Circular Motion

5.3.9Levers & Gears

5.3.10Stopping Distance

5.3.11Decelerations

5.3.12Stopping Distance - Calculations

5.4Pressure

5.4.1Pressure

5.4.2Pressure - Calculations

5.4.3Liquid Pressure - Calculations

5.4.4Pressure Changes

5.4.5End of Topic Test - Forces

5.4.6Exam-Style Questions - Pressure

6Waves

6.1Wave Basics

6.1.1Basics & Formula

6.1.2Wave Speed - Calculations

6.1.3Describing Waves

6.1.4Wave Frequency - Calculations

6.1.5Transverse & Longitudinal Waves

6.1.6Required Practical - Ripple Tank

6.2Waves at a Boundary

6.2.1Waves at a Boundary

6.2.2Waves at a Boundary 2

6.3Sound Waves

6.3.1Sound Waves

6.3.2Sound Waves 2

6.3.3Uses of Sound Waves

6.3.4Sound Waves - Calculations

6.3.5End of Topic Test - Introduction to Waves

6.3.6Exam-Style Questions - Wave Speed

6.4Electromagnetic Waves

6.4.1Properties

6.4.2Gamma, X-Ray & UV Light

6.4.3Infrared, Microwave & Radio Waves

6.4.4Properties 2

6.4.5Visible Light

6.4.6Visible Light 2

6.4.7Grade 9 - Waves

6.5Lenses

6.5.1Lenses

6.5.2Lenses - Calculations

6.5.3Images & Ray Diagrams

6.6Heat & Radiation

6.6.1Infrared Radiation

6.6.2Temperature

6.6.3Greenhouse Effect

6.6.4End of Topic Test - EM Waves, Lenses & Heat

6.6.5Exam-Style Questions - EM Radiation

7Magnetism

7.1Magnetism Basics

7.1.1Magnetic Materials

7.1.2Magnetic Fields

7.2Electromagnetism

7.2.1Electromagnetism

7.2.2Electromagnetism 2

7.2.3Motor Effect

7.2.4Magnetic Flux - Calculations

7.2.5Motors

7.2.6Induced Potential

7.2.7Induced Potential 2

7.2.8Generator Effect

7.2.9Generator Effect 2

7.3Transformers

7.3.1Transformers

7.3.2Transformers 2

7.3.3Transformers 3

7.3.4Transformers - Calculations

7.3.5Transformers 2 - Calculations

7.3.6End of Topic Test - Magnetism

7.3.7Grade 9 - Transformers

7.3.8Exam-Style Questions - Magnetic Fields

8Astrophysics

8.1Astrophysics

8.1.1The Solar System

8.1.2The Solar System - Calculations

8.1.3Orbits

8.1.4Orbits HyperLearning

8.1.5Life Cycle of a Star

8.1.6The Universe

8.1.7End of Topic Test - Astrophysics

8.1.8Exam-Style Questions - Astrophysics

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