Refraction Flashcards
What is the definition of refraction?
Refraction is the change in speed of a wave when travelling from one material to another.
When light refracts, what does and doesn’t change?
- Speed
- Wavelength
- Frequency does not change
What happens to light when it enters a more dense material?
The speed and wavelength decrease, and the ray changes direction towards the normal.
What happens to light when it enters a less dense material?
The speed and wavelength increase, and the ray changes direction away from the normal.
What does the refractive index, n, of a material indicate?
The refractive index tells us how optically dense the material is; a higher refractive index means more refraction.
How are angles measured in relation to refraction?
Angles are always measured relative to the normal, which is the line at 90° to the surface.
What occurs when light travels through a rectangular block?
Two refractions occur: once when entering the block and again when leaving the block.
How does the direction of a light ray change as it passes through a glass block?
The ray changes direction towards the normal when entering the block and away from the normal when leaving.
What happens when the angle of incidence is 0°?
The incident ray travels along the normal, with speed changes but no change in direction.
What happens to light as it leaves a semicircular block?
The light does not change direction because it is travelling along the normal to the curved edge.
What characterizes laser light?
Laser light is monochromatic, meaning it has a single frequency (colour).
What is dispersion of white light?
Dispersion occurs when white light is passed through a prism, splitting it into different colours.
Which colour of light refracts more: violet or red?
Violet light refracts more than red light.
What is the function of a convex lens?
A convex lens brings rays of light together to a focus.
What type of lens is used to correct short-sightedness?
A concave lens.
What type of lens is used to correct long-sightedness?
A convex lens.
What phenomenon causes fish in water to appear nearer to the surface?
Refraction.
What is Total Internal Reflection?
Total Internal Reflection occurs when light travels from glass to air and the angle of incidence is greater than the critical angle.
What is the critical angle?
The critical angle is the angle of incidence which gives an angle of refraction equal to 90°.
What is one application of Total Internal Reflection?
Optical fibres transmit light and information.
