To prove that what we see is often affected by what we expect to see with the help of the mirror image experiment.
1. Mirrors – 2 in number, square in shape, 12 inches (30 cm) a side, could be either made out of plastic or glass.
2. Epoxy glue and duct tapes.
3. Wooden dowels – 2 in number with diameter as 1 inch (2.5 cm) and 12 inches (30 cm) long.
1. Stick the mirrors together by pasting their backs. If you have a glass mirror then for safety, tape their edges using the duct tapes to seal the sharp edges. Take the two wooden dowels and paste them right in the centre of the mirrors vertically.
2. Hold the dowels with each hand and as you look at one side of the mirror move the hand which is on the other side. What do you actually see?
Your brain expects the image in the mirror to move as it is fooled to believe that the image it sees is actually your other hand. Thus when you move your other hand the nerves tells the brain that the hand is moving while the image which it sees doesn’t actually move. Our brain is tricked into thinking that the image should move according to the hand and hence the conflict arises which it doesn’t enjoy.
Heat waves also known as loo are common in summer. Heat can be generated from the suns rays. Heat can also be generated from electricity.
In this experiment we can learn how to produce heat chemically.
- Steel wool
- An empty jar with a lid
- Place the thermometer in the jar and close it with the lid. Wait for a few minutes. Take the thermometer reading.
- Take the steel wool and soak it in vinegar for a minute. Press the vinegar out. Cover the tip of the thermometer with the steel wool. Place the thermometer covered in the steel wool inside.
- Cover the jar with the lid and wait for a few minutes. Measure the thermometer reading.
The thermometer shows an increase in temperature.
How did it happen?
As the steel wool is soaked in vinegar, the vinegar removes the protective coating of the steel wool. This allows the iron present in the steel wool to rust. Rusting is actually a combination of oxygen with iron. When rusting happens, energy release in the form of heat occurs. The production of heat in the jar makes the mercury to expand and rise in the thermometer.
Geysers are natural springs which have the property of discharging hot water and steam into the air intermittently. Have you wondered if you could have one of your own? This science fair project is about building a homemade geyser.
Materials needed for the project:
- Plumber’s putty
- Boiling flask
- One hole rubber stopper
- Glass tube ( 0.5 to 1 meter length)
- Plastic container
- Hot plate
- Ring stand having an adjustable metal ring
- On the base of the plastic container, drill as hole such that it just allows the glass to go through.
- Put the hot plate close to the base of the ring stand and place the boiling flask filled with water on top.
- Insert the glass tube into the one – hole rubber stopper carefully. Slide the glass tube such that it reaches the other end of the stopper.
- Cap the flask firmly with the stopper and tube.
- Slide the metal ring to the ring stand so as to support the container
- Place the end of the tube into the bottom of the container. Set the tube in such a way that it protrudes a few inches above the container and below the rim of the container. To prevent the possibility of leakage seal of the gaps with Plumber’s putty.
- Align the center of the ring directly under the plastic container and tighten it firmly
- Fill cool water in the container. Pour enough water so that it fills the container by less than two centimeters
- Turn the heating element ON and watch.
When the geyser blows it will rest itself automatically by taking the cool water from the container back into the flask. After several eruptions we can find that the temperature difference between the water in the container and flask are negligible. When such as case happen, turn off the heating element and wait for the water in the container to cool.
How does this happen?
The process happens in three phases
Two main factors determine the duration of heating required to cause the eruption.
- The length of the glass tube
- The energy output from the heat source
A longer glass tube, more pressure developed in the flask. The increase in pressure required more heat to boil the water and it naturally takes longer time for the geyser to erupt.
Steam expands over 1500 times its initial volume and launches water of the geyser. (The pressure decreases as the liquid flows up the tube. This induces rapid conversion to steam from the liquid phase of water)
As the eruption slows, a small quantity of cool water in the container flows down to the flask below. This causes the steam in the flask and tube to condense, and decreases the pressure in the apparatus which allows the atmosphere to force more water to the flask from the container.
To conduct a simple experiment to demonstrate how a current carrying conductor generates a magnetic field.
- A one foot long coat hanger wire (With any insulation scraped off).
- A wooden stand with a flat surface at around halfway height.
- 5 or 6 small compasses.
- A 6 volt battery.
- Two electrical lead wires with alligator clips
- Make a hole in the centre of the flat surface of the stand and pass the coat hanger wire through it so that it is suspended vertically.
- Arrange the 6 compasses in a circle around the wire on the flat surface.
- Attach the lead wires to the battery terminals. Leave the other ends of the wires free for now.
- Observe the compasses now. You will see that all compasses point in the same direction, towards magnetic north.
- Now connect the battery terminals to the coat hanger wire using the lead wires. Observe the orientation of the compass needles now. Each compass will point in a direction tangential to a circle centred on the coat hanger wire.
- Rotate the support stand and observe again. The compasses will continue to point in tangential directions.
- Connect the battery to the coat hanger wire with opposite polarity by switching the lead wire clips and observe the compasses again. You will see that the compass needles now reverse the direction they are pointing in, but continue to point in a direction tangential to a circle centred on the wire.
Usually a compass lines up with the earth’s magnetic field. The north pole of the compass needle, which is itself a magnet points towards the south pole of the earth’s magnetic field as opposite poles attract each other. Now, when a current passes through the wire, it generates a magnetic field which is much stronger than the earth’s magnetic field. Hence the compass needle is now affected by both the earth’s magnetic field and the current carrying wire’s magnetic field. Since the latter is much stronger, the compass needle gets aligned with the wire’s magnetic field. This magnetic field can be visualized as a set of concentric circles with the wire as the centre. When the direction of current in the wire is reversed, the compass needle also points in the opposite direction as the magnetic field is reversed.
To understand the reason behind different colours we see when light reflects off a compact disc.
1.A compact disc which cannot be put to use later.
2.A white paper sheet.
1.Take the compact disc. Look at the side that is not printed under sunlight. We will see bands of different colours shimmering off the disc’s surface and also that the colours shifts as we incline or move the disc sideways.
2.Hold the piece of paper so that the sunlight reflecting off the CD falls on the paper. If there is not enough sunshine then turn off the lights and use a flashlight in place of sunlight.
3.Change the angle of incident light on the CD by tipping it. Also shift the paper so that the distance of the paper from the CD changes. Observe the changes in the colours.
4.Now look at the coating on the CD closely. You will see it has a coating of aluminium with plastic. The colour visible is because of splitting of white light off the aluminium ridges.
The compact disc has thousands of concentric circles on it. These circles are like projections in the disk which results in splitting of light when white light is incident on it. This is because of the reflection off the surface of the aluminium coating which are like projections and this is same as splitting of light by water droplets. With the change of angles of incident light on the CD when it is tilted, the waves tend to add together and form different colours or even cancel each other out. Thus certain colours of the spectrum are formed.
To understand the effect of temperature on water flow and the formation of convention currents in water.
- Food coloring
- Eye dropper
- Two ice cubes
- Warm tap water
- Marking tape
- One liter small-mouth jar
- 15O ml paper cup
- Using the pencil pierce four small holes near the bottom of the paper cup. Make sure the holes are evenly spaced evenly around the cup.
- Place the paper cup in such a way the rim of the cup rests on the mouth of the jar.
- Stick a tape on the outer portion of the jar to make a spot at a point 1 cm above the holes.
- Take the cup out, and fill the jar with warm water till the spot marked.
- Put the paper cup back into the jar and drop two ice cubes in the cup.
- Wait for 2 minutes
- To the water in the paper cup add 4 drops of food color.
As the water leaves the cup, it begins to twist and curl as moves down through the warm water. The reason for this trend is the fact that as warm water enters the cup it is cooled by the ice cubes. The warm water in the jar expands and the cold water in the cup contracts. The density of the cold water is higher than that of warm water and hence sinks through the warm water. This movement of water due to the variation in temperature is called convention currents.
What is the first thing that comes to your mind when someone asks you “Have you seen patterns in water?” You would probably imagine the ripples one sees when an object is popped into the water body. Other than this one is there any other pattern you could come up with?
No?? Usually we don’t see any other patterns. When water flows from one direction to another, patterns are formed. Since water is transparent, these patterns are not visible. Let us try out an experiment to make these patterns visible.
- Food Color
- A clear plastic jar with a tight lid
- Liquid hand soap with glycol stearate in it
- Clear tape
Take the bottle and add 3/4th of it with water. Put a few drops of food colour and add liquid soap to fill up the jar.
Close the jar securely. Shake it vigorously so as to make an even solution.
Make observations of the pattern when you do the following:
- Bottle is twirled
- Twirling is stopped
- Bottle is spun
- Bottle is shaked by turning the jar upside down
- Bottle is shaked by turning the jar side to side
The aim of this science fair project is to demonstrate the effects of air pressure and thrust. (A proof to Newton’s Third Law)
1. A balloon.
2. A straw.
3. Some duct tape.
4. Some string.
1. Blow up the balloon.
2. While holding the end of the balloon closed, use the tape to attach the straw to the surface of the balloon.
3. Pass the string through the straw and tie it at two ends of the room horizontally.
4. Take the balloon to one end of the string and release the end which you had been holding closed. The balloon will fly like a rocket across the room.
When you blow up the balloon, you are filling air in it at a higher pressure than outside the balloon. When you let go of the end of the balloon, this high pressure air will rush out to the low pressure surroundings. This movement of air will push the balloon in the other direction. This is called thrust.
If we add a color to a jar of water it will get colored. If we pour that water down, the color, which is dissolved in the water, will also go along with it. This science fair project is to experiment the same but using light!!
- A small glass jar with plastic lid.
- Thick insulation tape.
- Some Water
- A flash light.
- First, we should make two small holes in the cap of the jar. In order to help water steadily flow out through any one of the holes, the holes should made in such a way that it should be diagonally opposite to each other. (The water will flow out through one hole and the other hole will let air in.)
- Attach the flashlight to the bottom of the glass jar using insulation tape so that when the flash light is switched on the light goes through the jar. Also make the walls of the jar opaque using the insulation tape so that no light other than that from the flash light enters the jar.
- Now fill the jar with water and tighten the cap.
- Switch on the flash light.
- Slowly allow a thin stream of water to pass through one of the holes in the cap.
What do you see?
Due to total internal reflection, the light will be captured within the stream. We cannot see the stream from the side. The light will only be visible when the stream breaks up or hits something.
To conduct a simple experiment to understand how AC current creates an alternating magnetic field.
- A light bulb, preferably an elongated one.
- A powerful magnet.
- Keep the bulb in a holder which is within your reach.
- Switch on the bulb.
- Bring the magnet near the light bulb and observe how the filament of the bulb starts wiggling and shaking inside the bulb.
When an electric current passes through any conductor like a wire or a bulb filament, it creates a magnetic field. Just like a normal magnet, this magnetic field will also have a North Pole and South Pole. In the case of the light bulb, the current flowing through the filament is alternating current (AC) which is the type of electricity we get from the power supplies at our houses. In AC electricity flows in one direction and then switches and flows in the reverse direction. This happens 120 times a second. Each time the direction of current flow reverses, the direction of the magnetic field and the poles also reverses.
When you bring a permanent magnet near this alternating magnetic field, the filament of the bulb gets attracted and repelled alternately 120 times in every second. This causes the filament to shake and wiggle.