Revision list for Year 8 Physics

Topic 4 Waves

Transfer energy. Oscillations or vibrations which transfer energy but not medium. Properties: Frequency, Period, Amplitude, Wavelength, speed, different sorts of waves – Seismic, water, light sound, different sorts of oscillations – Transverse, longitudinal. Waves on water.

Light is a wave. Light travels in straight lines. Lasers, beams, etc. Transfers energy. Ray diagrams. We “see” things when light is reflected off objects into our eye. Transmission. Opaque, Translucent, transparent.

Reflection. Angle of incidence = Angle of reflection. Periscope, uses of mirrors. Inverted images. Use of a Normal.

Refraction. Bending light as it passes into out of different media. Normal. Refraction. Angle of refraction and angle of incidence. Light slows down when it goes into materials.There are angles which are not permitted – critical angle.

Dispersion. Prisms – Spectrum – what is happening? Why different colours. Two prisms can cancel or increase effect. ROYGBIV. (Frequency difference?) Find out and write up about Isaac Newton discovering about the spectrum of light. Reflecting prisms etc. Convex lenses

The Eye.How it detects colour. Rods and cones. Seeing in the dark. Blind spot. Structure of the eye. Why we have RGB TVs etc. The Pinhole camera – ray diagrams.

Colour – filters – reflecting / absorbing different components

Sound – vibrations, loudspeakers, interference in sound, what vibrates. Needs air to travel. Compression and rarefaction.

Amplitude, decibels, range of safe hearing. Ear defenders. Frequency range, Human audible range. Other animals.

The speed of sound – use multiples of data shared. How to calculate speed.

How the Ear works.

Topic 5 Forces

Introduction – pushes and pulls which when exerted, change motion, or change shape.

Examples of forces

  • gravity/Weight – keep pressing the point weight .ne. mass
  • Push/pull
  • Motive force
  • Tension
  • Stretching/squashing
  • Electric / Magnetic forces (EM forces)
  • Turning forces (with a pivot) - Torsion
  • Upthrust
  • Frictional forces
  • Drag
  • Air resistance
  • Fluid resistance
  • Act against motion – bigger the motion, bigger the force (Hence things stop usually in our everyday world – but note stationary is not the only state of no force )

Measuring force – Newtons

Weight is a force (Weight = Force x g)

Force represented as arrows with length of arrow being the size of the force and the direction.

Resultant force, Balanced force Unbalanced forces.

Speed = distance /time.

Speed is “similar to velocity” – extension: magnitude AND direction.

Forces change motion. Linear forces change linear velocity.

Acceleration is measure of rate of change of speed. Unbalanced forces make things accelerate.

Effect of forces –Change speed - Change shape.

Upthrust – forces on immersed bodies – Archimedes Principle ( Eureka ) Hot air balloons. Upthrust = weight of water displaced.

Forces are needed to change energy

Friction and other resistive forces change speed. They act to reduce motion.

Scientific process

Data analysis, table of results, precision, calculations, sharing data , plotting data

Important things for a method. Independent Variable, range how to change/measure. Dependent variable how to measure, repeats, mean anomaly, what to keep the same – fair test, what needed to be done.

What possible risks? How to control them.