'What we did' on Friday 10 February 2012Our main subject matter for the evening was a touch of physics and the subject of termperature.
During the evening a number of demonstration and interactive experiements took place which included the following:
A DEMONSTRATION of burning a small piece of Magnesium Ribbon which displays an itense white light. Magnesium Ribbons burns at well above 450C
INTERACTIVE - Air presure - Holding a glass tumbler upside down full of water supported only by a piece of cardboard. Demonstrating the effect of air pressure and surface tension. Carrying the tumbler carefully to the kitchen. This is a regular favourite with the children.
DEMONSTRATION & INTERACTIVE - Plasma Globes & Flourescent Tubes
'Jump Start' 1/2 flourescent tubes by holding one end and hovering the other ends of 2 plasma globes. Plasma Balls are really fascinating. There is a high voltage source attached to the inner ball that causes a current to flow to the nearest point with a lower voltage. The ball is filled with a gas that glows when it has electricity flowing through it. When nothing is touching the ball, the current just flows anywhere onto the ball. When you touch the ball, some of the current can flow through the glass and into you. Because your body is providing a place for the current to flow, the electricity keeps flowing and the lines of current can stay connected to the point on the ball that you are touching.
Lighting a Flourescent Tube with a Plasma Globe - see more detail & explanation here
INTERACTIVE - WHAT IS TEMPERATURE? - Each child held a test tube containing water. The water temperature varied from cool to warm. Thermometers were used to measure the temperature of the water and after a few minutes after warming the test tube, another reading was taken. We talked about important temperature readings ie 0C, 37C, 100C
Questions were asked about the movement of warm air and cold air.
DEMONSTRATION - USING A STRAW TO PIERCE THROUGH A POTATO
Using a stiff straw with thumb over end pierce the potato and it should go right through with no problem. Covering the top of the straw with yout thumb traps the air inside, forcing it to compress as you stab the straw through the potato skin. This makes the straw strong enough to pirece the potato. The low surface area of the straw end also helps.
DEMONSTRATION & INTERACTIVE - WE MADE SOMETHING OF A LIE DECTECOR - well not quite but it was an interesting experiment. We used a digital multimeter and projected readings through a projector so all could see the readout. A length of copper tube which was attached to one of the multimeter leads which was firmly held in one hand. The other lead was attached to a thick piece of aluminium foil and the other hand pressed on the foil. A very small voltage was produced at the point of the 'electrodes' when in contact with skin. Varying readings were recorded between 400 and 700 millivots. A higher reading was produced when the 'electrodes' were gripped or pressed hard.
DEMONSTRATION - RADIO - where do radio waves come from? Which direction? A transistor radio usually has 2 aerials, a telescopic one for VHF and a wound ferrite coil for medium and long wave. The wound ferrite coil is a very directional aerial. We tuned the radio to a local medium wave station. We found that when the radio was turned to a certain position the radio station could hardly be heard. This is called the 'null' position and the radio would then pointing at least in one direction to the transmitter.
WATER SURFACE TENSION AND THE AFFECT OF PEPPER & WASHING UP LIQUID
A dish of water which was sprinkled carefully with a fine layer of pepper. A drop of washing up on the end of a finger and just touch the middle. The pepper immediately spreads away to the edges. The affect of the washing up liquid changes the surface tension of the water.
The February issue of 'making science cool' booklet was handed out
- click here to see pdf copy
In all a fantastic evening for children and helpers
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