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9 Class Physics Working Models





Working models of physics:
Sound: Electric horn
We could make a working model of electric horn with the help of simple common scientific instruments available around us.

Materials required: dry cells, L shaped armature, stiff paper cut in a disc, copper insulated wire, corrugated cardboard and  magnet.

Working of Electric Horn:
>   The magnet is a bolt wound with a insulated copper wire and this is mounted on a angle bracket.
>    The armature which is L shaped is bent from a tin strip. 
>    The disk made up of stiff paper acts like a diaphragm and is glued at the small hole cut on the edge of the corrugated cardboard. 
>    The diaphragm and armature are attached by small sticks placed at each of the ends and with the help of a sealant.
>    The break in the current is made possible by the naked tip of one end of the magnetic wire touching the armature’s far side when the battery is switched off. 
>    Once we connect the free end of a winding over the magnet to one pole of the battery and the armature base to the other end, the current starts flowing through the coil.
>    As soon the current starts flowing through the coil, the coil due to magnetization pulls the armature. 
>    With the pull, the circuit is broken and this causes the armature jump to action again and repulsed to be attracted again. 
>    The sound produced by the armature’s vibration could be increased by a diaphragm made by paper attached to it.
>    The sound tone and its intensity could be controlled or adjusted by applying little pressure on the wire connecting it, while when a cone made by cardboard is pressed with the diaphragm, it results in louder sound.

Sound: Air Horn
Air horn produces a sound in very much the same way that of a tin horn or the vocals do. 
Some present day musical horns work on the same principle. 
The more powerful ones depend on the vibrations of a diaphragm which is pressed with the trumpet end.

Materials required: soda straw, funnel
 
Working
>    The straw is flattened one end of the straw and then cut about one fourth from each corner of the flattened end. 
>    Attach funnels of different sized and shaped over the other end of straw and that helps in magnifying the sound.

Energy: Hot box
The hot box is basically a solar energy based project where one could show the solar energy as a source of heat showcasing greenhouse effect.
Material required: hard card board, aluminium foil, black paint, duct tape, clear plastic

Working of hot box:
>    To start with we need to glue several layers of cardboard to all the sides and the bottom of the box.
>    The layers of card boards provide enough insulation and that helps in slowing down in the heat loss.
>    We have to make sure that the insulation is even in all sides of the box.
>    The aluminium foil has to be glued at the bottom of the box and paint the sides of the box in black.
>    As the paint is dried completely the box is then wrapped with the clear plastic and sealed with duct tape.
>    To make it work properly we could take readings after putting the hot box directly under the sun every 30 minutes and see the rise in temperature.

The Hydraulic Ram:
These are basically used for lifting water from a very low level to higher levels. 
Materials needed:
Rubber tubing
Glass T tube
Short length of glass tubing
Rubber stopper (single holed)
Plastic bottle

Set up:
> To begin with the bottom half of the plastic bottle is removed. 
> The short glass tube is inserted to the one holed stopper.
> The half cut bottle is then fitted into with the one holed stopper.
> Once done this is connected to a glass T tube. The T tube has to be attached with a rubber tubbing in one end and a jet tube on the other end with the help of a rubber tube.
> Once done we need to fill in the bottle with water and then pinch the tube at the end.
> Once done we should let the water run from the end of the tube.
> While doing this we have to stop the flow suddenly by pinching the tube quickly and at the same time mark the height to which the water would squirt from the jet tube. This helps in setting up the working model of a Hydraulic Ram.

Propulsion
Any propulsion system produces a thrust which helps in pushing an object forward. This is completely based on the third law of Newton’s third law which delves into action and equal reaction.

Materials required:
The materials required for these are 
Ring stand and clamp
Small heat resistive bottle
Glass tube with stopper
Bunsen burner
Iron stand/rod
Strings to attach the bottle

Set up
> To begin with the strings are tied around the bottle and then hang it from the iron rod stand.
> We need to make sure the bottle is free moving and can swing back and forth.
> Once this is done, we need to pour several millilitres of water into bottle and then insert the stopper with glass tube right at the mouth of bottle.
> Once done the bottle is heated in low flame until the water inside starts boiling.
> Once the water inside starts boiling, steam is produced and the bottle makes wild swinging movements.
> This principle helps illustrates the modern jet airliner propulsion.