light

• Light transfers energy from one place to another. It cannot travel through a vacuum.
• Light travels in straight lines. It is a transverse wave
• Shorter wavelengths = higher frequency and energy

  Longer wavelengths = lower frequency and energy
• When light passes through transparent materials, light is transmitted through these materials.
• When light passes opaque materials, then some are reflected while some are absorbed. This warms the object it hits on.
• When light hits a translucent material, the light leaves the material through different directions, it is scattered and you cannot see clearly through the material.
• Reflection: light bounces off an object. The angle of incidence is always equal to the angle of reflection. Also known as specular reflection.
• In reflection, when an opaque material reflects light, it travels through different directions, and this is called diffused reflection due to the roughness of the material.
• In a plane mirror, the object and the image made are:

  • of the same size
  • of the same distance from the mirror
  • has left and right swapped over.
• Refraction: light is bent when the light travels through different densities. Only happens when 2 substances meet together in their interface. If it passes through an interface of 90 degrees, it will not refract.
• In refraction:

  -Less dense medium to a more dense medium= bends towards the medium

  -Dense medium to a less dense medium = bends way from the normal.
• The focal length is the distance between the focal points and the lens. The focal point is where all the rays meet.
• CAMERA PARTS:

  -Sensor: changes the energy transferred by light into electrical signals, which are stored in a memory card.

  -Shutter: makes the light stop hitting the sensor when the camera is not in use. Shutter opens when picture is taken.

  -Aperture: hole that can be adjusted to allow different amounts of light into the camera.

  -Image: produced on the screen so the photographer knows the picture they are taking.

  -Lens: focuses the light. Position can be adjusted so that camera can focus on close or distant objects.
• EYE PARTS:

  -Iris: coloured part of the eye with a hole called pupil. Changes the size of the pupil in order to control the amount of light entering the eye.

  -Lens: focus the light

  -Transparent covering of the eye is known as cornea which focuses the light

  -Muscles changes the shape of the lens so the eye can focus on objects in different distances.

  -Blood vessels

  -Special cells in the retina change energy transferred by light into electrical impulses called nerve impulses. These impulses are sent to the brain via optic nerve.
• 2 different types of specialised cells in the retina.

  OUTER PART = Rod cells which detect low light levels and no colours

  CENTER OF THE RETINA = Cone cells with 3 types: red, green, and blue, which are the primary colours of light, and other colours come from these colours. All tertiary colours form to make white.
• Image that forms in the retina is upside down, but our brain helps us to see it the right way up.