Refraction through a rectangular block | Starter Quiz | Oak National Academy

What is represented by an arrow in a ray diagram?

• a peak of a wave

• a trough of a wave

• the edge of a wave

• the direction of wave travel

Answer explanation

A ray is represented by a line with an arrowhead and is used to show the direction in which a wave is travelling.

Which of the following statements about light is correct?

• Light cannot change direction.

• All types of wave can be reflected.

• A ray box produces a single ray of light.

• Light can only reflect from shiny surfaces.

Answer explanation

Light waves change direction when they reflect. All waves can reflect (e.g. sound, as an echo). Objects that are not shiny still reflect light, but in many directions. A ray box actually produces a beam, not a ray (a ray is an imaginary arrow).

Match the key words (relating to how light interacts with different objects) to their definitions.

• reflected

• taken in and loses energy inside the material of the object

• absorbed

• bounces off the surface of the object

• transmitted

• passes through the material of the object

Answer explanation

Light is transmitted when it travels through the material of an object, absorbed when it loses energy and ‘fades away’ inside the material of the object, and reflected when it bounces off the surface of an object.

In a ray diagram, the ray that approaches a surface or boundary is called the ___ ray.

Answer explanation

The incident ray is the ray that approaches the surface or boundary. For example, in a reflection ray diagram, the incident ray is the ray that points towards the mirror.

The ray diagram shown represents a light wave hitting a mirror. Which of the following diagrams shows the normal line (represented by a dashed line) drawn correctly?

• 
• 
• 
• 

Answer explanation

The normal line should be perpendicular to (at 90º to) the boundary (surface of the mirror) and intersect it in the same place as the incident ray.

The ray diagram shown is for a light wave reflecting from a mirror. A student has placed a protractor over the diagram. What is the angle of incidence?

• 27°

• 63°

• 77°

• 117°

• 123°

Answer explanation

On the protractor’s inner scale, the normal line is on 0° and the incident ray is lined up with 63° so the incident angle is 63°. On the outer scale, the incident ray is lined up with 117° and the normal line is on 180°; 180° − 117° = 63°.