IOP Institute of Physics

# Apparatus

On arrival
A bunch of flowers - chrysanthemums work well.

Activity 2
A bag of brightly coloured clothes – some for very cold weather (0˚C) and some for very hot weather (30˚C). E.g.: thick gloves, ski jacket, thick scarf, sun hat, thin tee shirt, sun glasses.

These should all be easy to either put on or hang against volunteers. Items for the upper body are best because they can be seen by the class.

Activities 3 to 10: Rope temperature scale

• A length of brightly coloured thin rope about 10 metres long
• 6 pieces of thin A4 card
• 6 clothes pegs
• Pictures (PowerPoint, 204 KB)

Choose the neatest end of the rope to represent absolute zero. Starting from this end, which represents absolute zero, tie knots at intervals using a scale of 100 Celsius degrees ≡ 1 metre (~ 100K ≡ 1 metre) as follows:

77 cm (liquid nitrogen liquefies), 216 cm (Antarctic), 273 cm (0˚C ), 330 cm (Sahara), 373 cm (water boils) and leave a long length of rope in a coil. Note that the positions of the knots do not have to be very accurate.

Print the pictures in the PowerPoint file and then glue them to cards or laminate them. (Alternatives are provided for 0˚C and 30˚C.)

Activity 5:
Video of water on hotplate (QuickTime Movie 4.4 MB)

or electric iron demonstration (Please read the safety notes)

• Electric iron
• Insulating mat
• Small quantity of water in a plastic bottle
• Safety glasses
• Gloves (As for liquid nitrogen)

Before the session, discuss this demonstration with the teacher. Agree which mains electric socket is to be used for the iron. If possible, this should be located behind your demonstration table. The iron should be placed on the insulating mat in a place where it cannot be reached by the children. A few minutes before the iron is needed, switch it on. When you perform the demonstration, unplug the iron and show the children that it is unplugged. Explain clearly that this is not an experiment for them to try at home. Hold the iron so that its base is uppermost and slash a few drops of water from a plastic beaker or bottle held in the other hand. Once the demonstration is over, replace the iron on the insulating mat ensuring that there is no risk of it falling over. Safety goggles should be worn for this demonstration. Gloves should be worn in case hot water splashes onto your hands and you drop the iron.

Activity 6 and 12 to 21

• Essential kit for use with liquid nitrogen. (Please read the safety notes)
• Dewar containing liquid nitrogen with venting lid – rated for nitrogen
• Thick, loose fitting leather gloves
• Safety goggles (not spectacles)
• Small Dewar flask – with a lid. (Special expanded-polystyrene flasks are available which eliminate the hazard of broken glass.)
• Tongs

Activity 12 to 22
Items needed for liquid nitrogen demonstrations:

• Small hand bell
• Hammer
• Banana
• Elastic band – preferably brightly coloured and fairly thick
• Length of cycle inner tube (Scrap tubes available free from some cycle shops.)
• Small soft toys and/or a tie or a ‘silk’ scarf
• Small balloon - a long thin one works well
• Blu-tack - small amount
• Block of expanded polystyrene packing large enough to hammer a blu-tack ‘nail’ into it
• If available - bouncing putty (obtainable from toy shops)
• Frying pan
• Egg
• An orange or stick of limp celery
• Finish with the flowers