cart Shopping Cart cart(0)

Benham's Disk Illusion

You will need:

  • Black pen, or a colour printer, plus paper.
  • 1 Nail, pencil, cardboard and glue.

Instructions


1. Print the picture shown or make your own on paper.

2. Glue the picture on some cardboard and allow to dry.

3. Pierce the middle of the disc with a nail.

4. Insert the pencil through the whole and spin the disc.

5. Do you see any colours on the disk?

6. Slow the disk to 3 - 5 rotations/sec and dim the light.


Benhams-Disk2
Benham's disc example that you can make yourself

Why Does This Happen?

 
Colour perception is achieved by three types of cells in the retina of the eye called cones.

With the three types of cones, one is more sensitive to red light, one is more sensitive to blue light and the other is more sensitive to green light. Each cone reacts at different speeds to light and keep responding for different lengths of time. You only see white when all three cones respond equally.

The alternating white and black flashes on the disk cause the cones to respond at different times and lengths, leading the brain to believe it is seeing coloured light.
 
Join our newsletter for more science teaching thoughts & ideas

Join the Fizzics newsletter

Back to human body experiments

>100 Free Science Experiments on this site!

Coloured shadows
  • Experiments to colour your class!
  • Easy & fun
read more
 
skeleton and student
  • Make fake blood & more!
  • Biology made simple
read more
 
electricity experiments
  • Circuit science for kids
  • Cheap materials found easily
read more
 
Vortex rings made with fog
  • Experiments using Newton's Laws
  • Step by step science
read more

School Science Visits: 

  • Highly engaging & curriculum-linked
  • Additional Teacher Support Resources
  • Professional visits in-class or via video conference
  • Both Primary School & High School science incursions
Call 1300 856 828 or use this form to discuss or make a show booking for your school!

Email updates

Signup to our monthly email Learn more
 

Contact us

1300 856 828
info@fizzicseducation.com.au

PO Box 272
Winston Hills, NSW, 2153, Australia
 
facebookgoogle plustwitter
linkedin youtube   ico6 pinterest