This video tutorial is a guide for next week's practical for CG18/12.
Using a hand-operated vacuum pump, we can demonstrate the relationship between pressure and volume of a gas. According to Boyle's law, the pressure of a gas of constant mass and temperature will be inversely proportional to its volume. In our demonstration, we will reduce the ambient pressure within the sealed container, hence allowing the higher
In what seems like a counter-intuitive demonstration, we can place a polarizing filter in between two other filters which do not transmit light in order to cause light to pass through again. This is because each filter will permit the components of electric field vectors of the electromagnetic waves that are parallel to its axis
Using a pair of polarizing sunglasses, you can demonstrate the effects of polarization together with a computer screen which is also polarizing. When the axes of polarization of the two polarizing screens are rotated, the brightness alternates between bright and dark. Light coming from a computer screen is usually polarized. In the video below, when
With the help of a simple manual vacuum pump that is used to keep food fresh, we can demonstrate the effect of a reduced pressure on the boiling point of water. This leads students to a discussion on what it takes to boil a liquid and a deeper understanding of the kinetic model of matter.
In a previous demonstration, we put a boiled egg into a flask with a mouth narrower than the egg. The challenge is now to remove the egg from the flask without breaking it. Materials Flask Egg Water Bunsen burner or candle Procedure Pour some water into the conical flask. Invert the flask quickly over a
This classic physics demonstration is used to show the effects of pressure difference between the atmosphere and a cooling volume of air. With a set of clean apparatus, you can even have the egg for a snack after that. Materials Hard-boiled Egg Flask or glass bottle with mouth smaller than the egg Paper measuring about
This demonstration requires no material other than your own fingers. Hold your index and middle fingers close to each other, leaving a small slit between them about 1 mm in width. Look through the slit into a source of light such as the window or a lamp. You will need to look with one eye up
Materials Wool PVC pipe or plastic comb String Lighter Procedure Hang the string from an elevated position. Leave the bottom end free. Rub the PVC pipe with wool. This deposits negative charges, or electrons, onto the surface of the PVC pipe. Place the side of the pipe that is rubbed near the string. You should
Materials Bar magnet Paper clip (stainless steel) Plastic clipboard Steel bookend Procedure Before the demonstration, make sure that the paper clip is not already magnetised by touching it with the steel bookend. If it gets attracted to the bookend, get a new paper clip. For the demonstration, first show that the paper clip can be