Select your class section and name to begin your personalised session.
Light energy travels outward from its source in straight lines called rays. This property is called rectilinear propagation. It explains why shadows have crisp edges and why a small hole can project an inverted image like a pinhole camera.
Move the sun across the sky and watch how the shadow changes direction and length. Toggle Construction Lines to see how a shadow is drawn in 2D.
Q1. Why does a flagpole cast a shadow on a sunny day?
Q2. At which time of day is a person's shadow the shortest?
You walk into a room with a perfectly polished mirror on one wall and a painted white wall on the other. Both surfaces are bright white and lit by the same lamp.
“You can clearly see your face in the mirror — but NOT in the white wall. Why?”
Click each surface to see what happens when light hits it. Observe the difference!
Smooth surfaces bounce light in one organised direction → a clear image forms.
Virtual image: same size, same distance behind mirror, laterally inverted.
Microscopic bumps send reflected rays in random directions → no image.
Q1. Why can you see your reflection in a mirror but NOT in a piece of paper?
Q2. The image seen in a flat (plane) mirror is best described as:
Learning Objectives
- Distinguish between regular reflection and diffuse scattering of light
- State the conditions necessary for regular reflection to occur
- Construct the path of a reflected ray using angles and a protractor
Drag the slider to change the angle of incidence. Watch the reflected ray respond. What pattern do you discover?
After experimenting with several different angles, describe what you discovered in your own words:
Exercise 1: A light ray hits a mirror at an angle of incidence of °. What is the angle of reflection?
(values personalised for )
Exercise 2: Both angles of incidence and reflection are always measured from:
The laws of reflection have been known since ancient times. Shine the UV torch to unveil them!
An incident ray must strike the reflecting surface.
Transparent objects allow light to pass through rather than reflecting it.
Rough surfaces produce diffuse scattering instead.
Q1. What is the key difference between regular reflection and diffuse scattering?
Q2. A ray hits a mirror at 35° to the mirror surface (not to the normal). What is the angle of reflection?
⚠️ Careful: the angle is from the mirror surface — you must convert to angle from normal first!
Q3. The normal line in a ray diagram is always drawn as:
Rotate the mirror to redirect the laser beam so it hits the target ⭐. Use what you know about i = r. 5 levels • 3 lives
The given angle of incidence is °. The normal and incident ray are drawn. Adjust the slider to draw the correct reflected ray, then click Verify.
Personalised for
- A horizontal plane mirror
- The point of incidence clearly marked
- The NORMAL as a dashed perpendicular line
- The incident ray at ° to the normal, with arrow
- The reflected ray at the same angle, with arrow
- Both angles labelled: i =° and r =°
Q1. Which surface produces regular (specular) reflection?
Q2. The angle between the incident ray and the reflected ray is 80°. What is the angle of incidence?
Q3. Why is diffuse reflection useful in everyday life even though it produces no image?
Q4. Which is NOT required for the law of reflection to apply?
| Section | Component | Score | Max |
|---|---|---|---|
| Auto-graded total | -- | 15 | |
| Game Bonus | 0 | 1 | |
| Drawing (teacher-graded) | pending | 4 | |
| Scaled Score /20 | -- | 20 | |