SKH Tang Shiu Kin Secondary School

Seeing an image formed by Reflection

Move Tommy and Cody. Can Tommy see Cody in the mirror? Watch the ray and Cody’s virtual image update.

Top view · drag people or mirror; use the angle control to rotate
LIVE VIEW
Tommy can see Cody
Ray hits mirror
BEHIND THE MIRRORIN FRONT OF THE MIRROR MIRROR TTommy CCody reflection point angle in = angle out
Light rayDotted path when blockedVirtual image
0°

What’s happening?

1 · Reflect

Light from Cody bounces off the mirror into Tommy’s eyes.

2 · Extend

The dashed extension behind the mirror locates Cody’s virtual image.

3 · Check

The incident and reflected angles are equal, measured from the normal.

Try this investigation

Drag Cody sideways until Tommy just loses sight of her. Notice where the ray would meet the mirror’s edge. Then drag her back until the reflection returns.