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PiP Feb 2015

  • C5-17: ROCKET BOTTLE

    C5-17
    Illustrate the rocket principle in a dramatic way
    Pour about 100-200 ml of liquid nitrogen into the bottle and install the stopper. Exhausting nitrogen gas and liquid result in motion of the bottle. An untethered stopper is available for comparison.
    OS6, I0, F2

  • I1-11 THERMAL EXPANSION - BALL AND HOLE

    I1-11
    Illustrates thermal expansion
    At room temperature the ball will not fit through the hole in the metal plate. When the plate is heated by a burner for about 30 seconds, the ball easily fits through the hole
    I1, I0

  • I1-17: THERMOSTAT - MODEL

    I1-17
    Model of use of a bimetal strip in a thermostat.
    A bimetallic strip is set up to complete a circuit and turn on a bulb, as a model of how thermostats move with changing temperature to control furnaces or air conditioners. Heat the bimetal strip so that it curves toward the wire. When it touches the wire it completes the circuit, lighting the bulb. This is similar to the mechanism in a real bi-metal strip thermostat to turn on and off the power to the appliance.
    I1, I0, K6

    i1-17a

  • I1-18: BIMETALLIC STRIP THERMOMETERS

    I1-18
    Allow students to see how bimetallic strips are used in thermometers and thermostats.
    The case has been removed from a thermometer and thermostat mechanism for a household furnace thermostat. Important parts, such as the bimetallic strip and the mercury switch are clearly visible.
    I1

  • I1-61: DUST EXPLOSION

    I1-61
    Produce a dust explosion.
    A rounded tablespoon of lycopodium powder placed in the funnel is blown upward by blowing into the end of the rubber tube, which can be stretched out. When the cloud of powder reaches a burning candle flame, on the top mount, it ignites readily to create a dust explosion. This is a very dramatic effect.
    I1, I0, C2, FS2

    i1-61ai1-61b

  • I1-63: HYDROGEN EXPLOSION

    I1-63
    Produce a hydrogen explosion

    A balloon filled with hydrogen is tethered about six feet above head level. The burning match on a stick is positioned under the balloon, creating the hydrogen explosion.
    Engagement Suggestion
    • One option for presenting this would be to compare the behaviour of two different balloons, hydrogen and helium. You can tell students what is in each balloon and have them make a prediction about what each will do, or show the demonstration first and then have students analyze why the results were different.
    I1, I0, FS1

    I1-63B

  • I2-21 THERMAL CONDUCTIVITY IN METALS

    I2-21
    Demonstrates thermal conductivity in various metals
    Heat from a gas burner at the center is conducted along rods of copper, aluminum, and brass. Wax blocks at the ends of the rods melt and drop off the rods due to the conduction of heat, in the following order: copper (3.98 Watts/cm deg C), aluminum (2.37 Watts/cm deg C), and brass (1.23 Watts/cm deg C).
    I2, I0

  • I2-22 THERMODYNAMICS BY TOUCH

    I2-22
    Demonstrates that touching a material tells something about its conductivity, not necessarily its temperature
    Various materials, all at room temperature, are arranged on a cart, and students are invited to touch them. The materials in order of increasing conductivity, are: styrofoam, wood, plastic, slate, steel, aluminum, and copper.
    I2

  • I2-28: WATER BALLOON AND CANDLE

    I2-28
    To demonstrate the transfer of heat by water
    A balloon filled with water is held above a candle flame. Contrary to most students' expectations, the balloon does not burst. The water in the balloon conducts heat away from the rubber before it can melt.
    I0

  • I2-43: CONVECTION - HOT PLATE

    I2-43
    See convection currents.
    The irregular refraction patterns created by convection currents in air heated from below are easily seen when light from a point source (foreground) shines through the air over a hot plate and onto a screen. This phenomenon is often seen when the sun shines brightly onto surfaces like cars and roads, and is responsible for the twinkling of stars.
    I0, LS1

  • I2-44: CONVECTION - CANDLE IN CYLINDER

    I2-44
    Demonstrate the mechanism of convection.
    A lighted candle lowered into the graduated cylinder goes out quickly because the buildup of gaseous products of combustion at the bottom of the tube prevents it from getting oxygen. Lowering the smaller tube into the larger graduated cylinder just above the candle flame separates the rising hot air from the falling cold air, allowing convection currents to feed oxygen to the candle flame.
    I2

  • I3-04: GALILEAN THERMOMETER

    I3-04
    Illustrate a very heat-sensitive device.
    This air thermoscope consists of a flask sealed with a stopper with a 4 mm diameter 50 cm long glass tube inserted into the (colored) water bath in the bottom of the flask such that the water level in the tube is at the level of the water in the flask. The water level in the tube rises when the flask is warmed by snuggling it in your hands.
    I3

    i3-04a

  • I3-33 HELIUM BALLOON ON LIQUID NITROGEN

    I3-33
    Demonstrates how a gas contracts when cooled
    A helium balloon which is cooled by resting on a liquid nitrogen bath becomes becomes more dense -- by about a factor of 4. When the balloon is removed from the liquid nitrogen it warms up, expands, and floats away, unless it is tethered
    I0, FS1

    I3-33A

  • I4-14: CHANGE OF STATE WITH BANG

    I4-14
    Demonstrate that the volume of a gas is much greater than the volume of the same amount of liquid.
    Fill the small flask with liquid nitrogen and place the balloon over the top. As the liquid nitrogen turns to gas its volume increases, ultimately bursting the balloon. This is a change of state with a bang, hee, hee, har, har.
    I4, I0

  • I4-15 CONDENSATION OF STEAM - GALLON CAN COLLAPSE

    I4-15
    Illustrates forces produced by the pressure drop when steam condenses into water
    A small amount of water in the can is heated with the lid off, filling the can with steam. The can is then removed from the hot plate and the lid quickly screwed tightly thereon. Within a few seconds the steam begins to condense, creating a low pressure inside the can. The greater atmospheric pressure outside crushes the can.
    I0, SU14

  • I4-16: DRINKING BIRD

    I4-16
    Stimulate thought about heat exchange and liquid-vapor phase transitions.
    The bird's head and beak are initially wetted, and the bird positioned so that its beak will dip into the water cup when it tips (whether or not the cup is there). The liquid sealed in the glass chamber is reported to be tri-chloro-mono-fluoro methane.
    I4

  • I4-17: AIR BALLOON ON LIQUID NITROGEN

    I4-17
    Demonstrate dramatically that the volume of vapor is greater than the volume of the same amount of liquid.
    An air balloon is held on top of a liquid nitrogen bath. The volume of the air balloon decreases for two reasons: first, the volume of the gas shrinks according to Charles' law, and second, some of the air changes to liquid and shrinks considerably. Liquid nitrogen will readily cause oxygen to liquify, and even liquify some of the nitrogen in the balloon.
    I0

    i4-17a

  • I4-31 ICE BOMB

    I4-31
    Demonstrates forces created by freezing water
    A pipe elbow with end caps is filled with water, sealed by tightening the ends, and dropped into a metal container of liquid nitrogen. Within about one minute the water freezes, expanding sufficiently to break the cast iron with a loud crack and a big cloud of vapor.
    I0, I4, SU5, OS6

  • I5-22 FIRE SYRINGE

    I5-22
    Demonstrates heating air by compression

    This demonstration consists of a transparent cylinder with a flared base, and a plunger that can be pushed into it. A small (very small) piece of cotton is pushed into the bottom of the tube using the wire provided, and the plunger is sealed into the tube. The plunger is pushed down sharply, compressing and thereby heating the air within. The temperature rises high enough to ignite the cotton with a flash, which can be readily seen through the plastic tube.
    Engagement Suggestion
    • Consider inviting a volunteer from the audience to try the demonstration. This will require careful supervision, but is safe. Just ensure that the syringe isn't knocked off the table by an overenthusiastic student!
    • This demonstration works best with a very small amount of cotton to ignite, no more than a few millimeters at most. Consider showing the device with different amounts of cotton, and how the results change. Encourage students to discuss reasons for this.
    Background
    This demonstration illustrates that an essentially fixed mass of air will increase in temperature when its volume is reduced, i.e. it is heated when compressed. The fire syringe is a simple piston, and can be used to introduce a discussion of the use of pistons in engines.

    Consider using this demonstration in conjunction with both other thermodynamics demonstrations from section I5, and relating it back to general gas behaviour with demonstrations from section I3.
    I5

  • L3-14 LARGE CONCAVE MIRROR (60cm)

    L3-14
    Shows types of images from a concave mirror
    Observe and describe the image of the class sitting in front of the mirror when the mirror is at a reasonably large distance away (inverted, small, real). Ask your students if they have this kind of mirror at home. After they say no, hold the mirror close to your face an let them view the image by turning your back to the class, producing an upright, large, virtual image.
    OS8

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