A torch is a portable handheld electric light. A typical torch consists of a light source mounted in a reflector, a battery, wires and a switch.
The source of light is an LED ie light emitting diode. In LED the longer leg is positive end and the shorter leg is negative end. It is a diode that allows current to flow only from positive end to negative end.
A dry cell converts stored chemical energy into electrical energy. Two or more cells form a battery.A dry cell is a zinc carbon cell. It produces voltage of about 1.5 volt. Zinc container act as negative electrode, carbon rod acts as positive electrode.The electrolyte used is a moist paste of ammonium chloride and zinc chloride. It is made up of metallic cylinder. It has a flat case and metal cap on top.The metal cap is positive end of cell and flat base is negative end of cell.
The switch is an electric device that is used to make or break the circuit.
Due to chemical reaction inside the cell, excess electrons are produced on negative end.
When the cicuit is closed with a conductive path, the electrons are able to travel to the positive end. Thus in turn provides power to LED. Inside the LED the electrons recombine with the holes and energy is released in the form of light.
When the switch is in off position, the circuit is not complete and the current doesnot flow through it. Such circuit is called an open circuit.When switch is in On position the circuit is complete and current flows through it. Such circuit is called closed circuit.
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Step 2: Connecting and Checking the Circuit
1. LED( 1)
2. Wires (3- cut wires of about 10 to 15 cm)
3. Battery holder (1)
4. Dry cell of 1.5 V (2)
5. Switch (1)
1. Insert cells in battery holder.
2. Connect the positive( longer leg ) of LED with positive of battery.
3.Connect negative of battery with one terminal of switch, the other terminal of switch should be connected to negative ( smaller leg )of LED as shown.
4. Switch ON to test if its working or not.
Step 3: Making Cylinder Cover for Flashlight
1. Cut a thick A4 size paper in half
2. Use one half to make cylinder shape
3. Make sure the diameter of roll should be enough to fit battery.
4.A circle master can be used to make cylinder as shown
Step 4: Making Little Changes in Cylinder
1. Make triangular tabs on both the edges of cylinder so that it can be glued to cover with a circle on one side and a reflector on other side.
2. Make hole almost near the middle of cylinder so that switch can be inserted there.
Step 5: Insert Battery and Switch
1. Disconnect the circuit and insert battery
2.connect switch as shown.
3. Take out two terminal outside the cylinder so that LED can be connected with it.
Step 6: Make a Reflector
Reflector converges and focus the light in single direction
To make a reflector,
1.Glue an aluminium foil on a sheet of paper and cut a big circle of approx 14cm diameter.
2. Make a slit as shown to make a cone shape.
Step 7: Insert LED
Cut the tip of cone and insert LED
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