# Physics at home

##### How do we explore the world?

Below are some thought provoking experiments. Most can be done using stuff from around the house, others need a bit more.

## The thunder tube

The ‘Thunder Tube’ is just a variant on the Talkie Tape principle. It just creates and amplifies sound in a more random, but rather loud way. This one has a thick cardboard tube with a thin plastic diaphragm glued to one end. The other end is open. A long, thin spring pierces the plastic a little and is glued in place on the inside.Drawing a thumbnail along the spring, allowing it to bang against solid objects or simply shaking the tube creates a very loud sound –like thunder!

## Oven shelf gong

Adapted from the IOP ‘Marvin and Milo’ series ‘Do Try This at Home’

## Magic lenses

A cylindrical lens inversion effect is seen when the glass is filled with water. The girl magically swaps the balloons from her left hand to her right as the glass fills. This is commonly done with a horizontal arrow behind the glass which flips the direction it points in when the water is poured in. Try it with other pictures or words.

## Disapearing cross

Place a cross on a card under a tall beaker. IAsk your audience to put their hands up if they can see the cross. With a bit of luck, most should. Gradually fill the beaker with water, asking the audience to put their hands down if they can no longer see the cross. Provided the beaker is tall enough and no-one is standing too close, all hands should now be down!

## Magic mirror

Look at the reflections of the words in the mirror. What do you observe? Can you think of a hypothesis to explain it?

## DVD spinners

These simple spinning tops can create some very interesting effects.The three on the rightof the picture are ‘strobe disks’. They give interesting rotating and counter-rotating effects under fluorescent lights as they slow down. This is because the lights flicker slightly fiftytimes per second. The effect is similar to that which makes wagon wheels in old western films appear to be rotating backwards at times. In that case, the frame rate of the film provides the strobe effect. They don’t work with LED lights unfortunatly

These spinners are made from DVDs with a marble glued in to the hole as a bearing, and a plastic bottle top glued to the top by which to spin them. You can also heat a coin and insert it through the hole as a pivot (care!). Templates for the disk patterns are readily available online.

## Magic ball swap

Place the polystyrene ball just under the surface of the rice with the metal ball on the surface, but not directly above it. Now vigorously shake the rice tub from side to side with small, fast movements.

## Pepsi v Diet Pepsi

What happens when you drop a can of fizzy drink and its diet equivalent in water? Can you explain it?