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Activity

Gravitational lensing model

Summary: 
Use the bottom of a wine glass to model gravitational lensing.
Science content (2016 curriculum): 
Physics: Motion and Forces, Newton’s Laws, Gravity (K, 2, 6)
Earth/Space: Sun, Moon, Solar System, Universe (1, 4, 6)
Materials: 
  • wine glass, ideally just the base
  • white paper and coloured pens
  • optional: paper with printed geometric designs (see attachment)
  • optional: other cut glass objects
Procedure: 

Before the lesson:
Buy cheap wine glasses. Knock the base off them by tapping the stem just above the base with a metal file or other long, heavy object. Sand down the sharp edges.
Alternatively, use an intact wine glass, but be careful about breakages in the classroom.

Hand out wine glass base lenses, and optionally, other cut glass objects that bend light into interesting patterns.
Hand out paper with printed geometric designs (attachment), and coloured markers for students to make their own designs.
Ask students to move the lenses over the designs and notice how the lenses bend images.
Challenge them to specifically make a circle from a dot. If they need help: slide the wine glass base over the dot until the stem is directly above it, when the dot changes to an arc then a circle.

The wine glass base models how gravitational lensing works. When the wine glass lens is run over a dot, the light from the dot is bent by the lens, so our eyes above the wine class see a circle.
In the same way, astronomers use their telescopes to look for rings of light to discover dense masses in the universe, which can bend light around them. When light from a far away galaxy passes through a nearer black hole or cluster of galaxies, their immense gravity bends the light around them, so that the light that reaches our telescopes appears as an arc, or even a circle.
Try these webpages for images of gravitational lensing of light around black holes or galaxies: https://en.wikipedia.org/wiki/Einstein_ring http://static.ddmcdn.com/gif/blogs/6a00d8341bf67c53ef01630128de99970d-80...

Gravitational lensing images provide information on several astronomical phenomena:
They can be used to map where black holes are.
They can be used to map the dark matter in the universe, which cannot be seen but has enough mass to bend light.
Dark energy existence has been supported by gravitational lensing images.
Cosmic microwave background radiation is also bent by gravitational lensing, so is studied this way.
Galaxy clusters can be weighed with from gravitational lensing images, as the amount of lensing depends on the mass.
Early universe galaxies can be seen and studied with gravitational lensing, which magnifies light images (lensing arc image).

Attached documents: 
Notes: 

Sharon had a sub

Grades taught: 
Gr 4
Gr 5
Gr 6
Gr 7
Teacher: 
Alane Lublow
Heather Wallace
Phyllis Daly
Reid McInnes
Scott Malin
Sharon Ghuman
Teaching site: 
Strathcona Elementary
Tyee Elementary
Activity originally developed and delivered: 

Strathcona Elementary with the Vancouver School Board's Scientist in Residence Program