Electromagnetic Wave 2 - Light Wave

Card 1: Reflection of Light Wave

Reflection of Light Wave

The characteristic of reflection of light enables us to see objects.

Objects that do not emit light are not seen in the dark.

An object only is seen if light is incident on it a reflected back to our eyes

Card 2: Refraction of Light Wave

Refraction of Light Wave

When light travels one medium to another of differing density, its speed changes.

Speed of light is higher in a medium of less density as compare with one higher density.

The change in velocity of light when it travels from one media to another of different density results in the refraction phenomenon.

Card 3: Diffraction of Light Wave (Single slit experiment)

Diffraction of Light Wave -Single slit experiment

  • Light is diffracted if it passes through a narrow slit.
  • Diffraction pattern is made up of the bright bands and dark bands of different width.
  • The central band is wider and brighter. The dark and bright bands of narrower width are alternatively observed on the left and right side of the central bight band.
Card 4: Condition for Diffraction to Take Place

Conditions for diffraction to take place are:

Light source must be monochromatic. That is, the light must possess only one wavelength.

Slit size must be small enough as compare with the wavelength of light.

Card 5: Factors affecting the pattern of diffraction

Factors affecting the pattern of diffraction

Size of the slit - Smaller size, diffracted more

Colour of the light - Longer wavelength, diffracted more

Distance of the screen from the slit

Card 6: Interference of Light Wave - Young's Double Slit Experiment

Young's Double Slit Experiment

Young's double-slit is made up of two slits ruled on a piece of slide and painted with 'aquadak'.

  • When monochromatic light passes through the Young's double-slit, diffraction of light occurs and two coherent sources (same amplitude, frequency and phase) are produced as shown in the diagram above
  • The two coherent sources will overlap and superpose to produce the effects of constructive and destructive interference.
  • Constructive interference generates bright fringes while destructive interference produces dark fringes.
  • Fringe size of bright fringes and dark fringes are about similar in size. Fringe separation between any dark fringe and a neighboring bright fringe which alternates in position with the former is the same.
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