Physics

Physics

1. Waves

   • Sound
     • Audible range of sound for humans: 20Hz - 20,000Hz
       • Anything higher than 20,000Hz is called ultrasound
         • Some animals can detect ultrasonic waves
           • Bats
             • They use echolocation to find their way in the dark.
             • They use echolocation to find their way in the dark.
             • They use echolocation to find their way in the dark.
           • Dolphins and whales
             • Cf
             • They use ultrasound to communicate
             • They use ultrasound to communicate
             • They use ultrasound to communicate
         • Ultrasound is used for many things
           • Cleaning jewellery
           • Heart scans
         • Ultrasound is used for many things
           • Cleaning jewellery
           • Heart scans
         • Ultrasound is used for many things
           • Heart scans
           • Cleaning jewellery
       • Anything lower is called infrasound
         • Some animals can detect infrasonic waves
           • Pigeons
           • Elephants
   • Light
     • Colours
       • White light
         • White light is a mixture of many different colours, each with a different frequency. White light can be split up into a spectrum of these colours using a prism
           • We see different colours on objects because the white light hits the object
             • The object - for example a blue shirt - absorbs all the colours except blue, which it reflects
               • This is why we can see different coloured objects
     • Refraction
       • Occurs when light passes through one medium to another
       • The normal is an imaginary line perpendicular to the surface of the medium the light is leaving
         • When passing into a less dense material, light refracts away from the normal
   • Frequency
     • The number of crests of a wave that move past a given point in a given unit of time
     • The frequency can be calculated by dividing the speed of the wave by the wavelength
   • Amplitude
     • The vertical distance between a peak or valley and the equilibrium point
     • The greater the distance, the more energy the wave is carrying
   • Wavelength
     • the distance between successive crests of a wave
     • To calculate it, divide the speed by the frequency
   • Longitudinal Waves
     • Sound
   • Transverse Waves
     • Light
     • Sound is represented on an oscilloscope with transverse waves
   • Frequency
     • The number of crests of a wave that move past a given point in a given unit of time
     • The frequency can be calculated by dividing the speed of the wave by the wavelength
   • Amplitude
     • The vertical distance between a peak or valley and the equilibrium point
     • The greater the distance, the more energy the wave is carrying
   • Wavelength
     • the distance between successive crests of a wave
     • To calculate it, divide the speed by the frequency
   • Longitudinal Waves
     • Sound
   • Transverse Waves
     • Light
     • Sound is represented on an oscilloscope with transverse waves
   • Transverse Waves
     • Sound is represented on an oscilloscope with transverse waves
     • Light
   • Wavelength
     • To calculate it, divide the speed by the frequency
     • the distance between successive crests of a wave
   • Amplitude
     • The greater the distance, the more energy the wave is carrying
     • The vertical distance between a peak or valley and the equilibrium point
   • Frequency
     • The frequency can be calculated by dividing the speed of the wave by the wavelength
     • The number of crests of a wave that move past a given point in a given unit of time

2. Energy

3. Electricity

4. The Eyes

   • Lenses
     • There are two types of lended
       • Concave
         • Concave lenses are thinner at the middle. Rays of light that pass through the lens are spread out (they diverge). A concave lens is a diverging lens.
           • When parallel rays of light pass through a concave lens the refracted rays diverge so that they appear to come from one point called the principal focus.
             • The principal focus
               • the point on the axis of a lens or mirror to which parallel rays of light converge or from which they appear to diverge after refraction or reflection.
                 • Lenses can help to correct vision in the form of glasses. They help the retina to focus better
       • Convex
         • Convex lenses are thicker at the middle. Rays of light that pass through the lens are brought closer together (they converge). A convex lens is a converging lens.
           • When parallel rays of light pass through a convex lens the refracted rays converge at one point called the principal focus.
   • The retina
     • the retina is a layer at the back of the eye with light detecting cells
       • where the images that the eyes see are formed.