Topic 3.2 - Light Flashcards Preview

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Flashcards in Topic 3.2 - Light Deck (37)
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What happens when rays of light hit a plane mirror?

They are reflected.


What are the characteristics of an image formed from a plane mirror?

  • The same size as the object

  • On the the same side of the mirror as the object

  • An inverted (upside down) version of the object


When light is reflected how do angles i and r compare?

angle of incidence = angle of reflection


How are the angles of incidence and reflection measured?

Relative to the normal.


What is a virtual image?

An image produced on the same side of the lens as the object.


What is a real image?

  •  An image produced on the opposite side of the lens from the object.

  • A real image can be formed on a screen as the light rays cross after the lens.


What kind of image is produced by a plane mirror?

A virtual image.


What is refraction?

  • Refraction is the change in speed of a wave crossing a boundary between two media, resulting in a change in direction.


Which property of a wave is not changed by refraction?

The frequency


What is the critical angle?

The angle of incidence which produces an angle of refraction of 90°


What is internal reflection?

When light rays reaches a boundary and some of the rays are reflected back into the medium which it came from.


What is total internal reflection?

When a ray of light is fully reflected back into the medium it came from, when reaching a boundary between media.


When does total internal reflection occur?

When the angle of incidence is greater than the critical angle.


Define refractive index

The ratio of the speed of light in a vacuum to the speed of light in any given medium.


Give the equations for refractive index


When light passes through a converging lens...

The light rays bend towards the normal, and meet at a focal point.


What is the principal focus of the lens?

A focal point before a convex lens, from wich light rays appear to come from, or the focal poiny afdter a concave lens where all the rays meet.


Draw a diagram of light rays through a converging lens


How can lenses act as magnifying glasses?

By producing an enlarged, virtual image.


How does wavelength affect refraction?

Shorter wavelength waves refract more


What happens when white light is shone through a prism?

It separates into a spectrum of all its coloured light components.


Why is white light separated by a prism?

Each different coloured light wave has a different wavelength. The shorter wavelength lights like blue refract more while the light with the longest wavelength red refracts the least. This creates a spectrum  


List, in the correct order, the colour spectrum produced by the dispersion of white light

Red, orange, yellow, green, blue, indigo and violet.


What is monochromatic light?

  • Light that has a single frequency 
  • A laser light is an example of a monochromatic light 


What are the conditions for total internal reflection?

  • The light is travelling from an optically denser medium (higher refractive index) to an less optically dense medium
  • The critical angle is exceeded


What do Optical Fibre do?

Optical fibres transmit light by total internal reflection.


What are the key features of an optic fibre?

  • Core 
  • Cladding 
  • Protective Coating 


What are optical fibres used for?

  • Internet providers use optical fibres to set up quick and reliable internet connections.

  • They can be used for endoscopy


Do optical fibre lose lots of information?

No they don't they are able to transmit huge amounts of information with few information losses


What is the focal length?

The focal length is the distance from the centre of the lens to the principal focus