Light Bending at a Glass Surface

In the picture

1. 1The incoming ray in air, travelling towards the glass surface
2. 2The dashed normal, perpendicular to the surface at the point where the ray strikes
3. 3The angle of incidence, between the incoming ray and the normal
4. 4The reflected ray, leaving the surface back into the air
5. 5The refracted ray, bent towards the normal inside the glass

Examples

• A straw in a glass of water looks broken at the waterline.
• A mirror on a wall sends sunlight back across the room.

Quiz: Light Bending at a Glass Surface (Age 13)

1. 1

   When light reflects from a surface, how is the reflected ray related to the incoming ray?

   • It leaves at the same angle measured from the normal.
   • It leaves at a smaller angle measured from the normal.
   • It leaves at a larger angle measured from the normal.
2. 2

   Why does light bend when it passes from air into glass?

   • Because the glass absorbs all the light.
   • Because its speed changes in the glass.
   • Because the light changes colour in the glass.
3. 3

   At a glass surface, what happens to the light ray that arrives from air?

   • Part reflects back into the air, and part enters the glass and bends.
   • All of it passes into the glass without changing direction.
   • All of it reflects back into the air.

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.