Physics Summer Exam Revision

• Luminous light sources


  The Sun, Fireflies, Lightbulbs
• Non-luminous light sources


  Book Moon, Football
• Light


  • Travels in a straight line
  • Called Rectilinear propagation
• If an object gets closer to the screen

  Shadow becomes smaller
• Factors affecting size of shadow

  • Size of light
  • Distance of light from screen
  • Size of objects
  • Brightness of light
• Name the EM Spectrum in order. Name which one has the highest and lowest wavelength and frequency


  Radio, Microwave, Infrared, Visible, Ultraviolet, X-Ray, Gamma

  Radio: Highest Wavelength, Lowest Frequency

  Gamma: Shortest Wavelength, Highest Frequency
• What is the Law of Reflection?

  Incident Ray = Reflected Ray
• Put the colours of visible light in order

  Red, Orange, Yellow, Green, Blue, Indigo, Violet

  Longest Wavelength ———————————Shortest Wavelength
• Primary colours

  Red, blue, green
• Secondary colours


  Magenta, yellow, cyan
• Magenta


  Red + blue
• Yellow


  Green + red
• Pinhole camera


  Simple camera that takes pictures with no lens, light rays enter the aperture and cross, resulting in an inverted, in-focus, smaller black and white image
• Sound


  Caused when an object vibrates, causing particles to vibrate and form a pressure wave that is transmitted
• Sound waves


  • Oscillations are parallel to the direction of energy transfer
  • Longitudinal waves
• Frequency


  Number of waves per second
• Sound waves need a medium to travel through
• Emission


  When something produces its own
• Transmission


  When light is transferred from one place to another
• Absorption


  When light is taken in by a substance
• Reflection


  When light is reflected
• Speed of sound

  300m/s in air
• Equation for Speed of sound

  Speed = Distance / Time
• Echo


  Reflection of sound used by bats to locate prey and estimate the speed of sound
• Bell in a bell jar experiment

  1. Bell is placed in a bell jar

  2. Air is pumped out

  3. Particles needed for sound to travel are removed

  4. Sound fades from the bell
• High Frequency High amplitude

  • This means a high pitch. This means a high sound
• Low amplitude, Low Frequency

  • Low sound, Low pitch
• What are filters used for?

  They help alter the colour quality of the light to match the colour sensitivity of something
• How do objects appear in coloured light

  Blue shirt in cyan light: Appears blue

  Green hat in red light: Appears black

  Red shoes in magenta light: Appears red

  Blue dress in blue light: Appears blue
• How do filters work?

  A yellow filter absorbs all colours except yellow. Yellow is transmitted. But when yellow light is transmitted and travels into a green filter no light is transmitted.
• Uses and dangers of Radio


  Uses- Radio communications and satellite transmissions.

  Dangers - Heating os biological tissues
• Uses and dangers of microwave waves

  Uses - Radar technology and microwave ovens to heat food.

  Dangers - Internal heating
• Uses and dangers of Infrared and Visible

  Uses of Infrared - Electric Heaters

  Dangers of Infrared - Skin Burns

  Uses of Visible - Fibre optic cables and Photography

  Dangers of Visible - Blindness
• Uses of UV, X-Ray and Gamma

  UV - Uses - Tanning

  Dangers - Ionising cells

  X-Ray - Uses - X-Ray scans

  Dangers - Ionising cells

  Gamma - Uses - Sterilising medical equipment

  Dangers - Ionising cells