Lakshmi GopiReddy Adventures in STEM Electromagnetism

Magnets Magnetic field flows from North to South in almost circular fashion

Activity 1 Connect the electromagnet to the battery. ▫ What happens when you place a magnet at the ends of the nail? ▫ Use a compass and find the poles of the magnet. ▫ What happens when you reverse the terminal connections on the battery? ▫ Can you explain how an electromagnet works? 3

Electromagnets the direction of the magnetic field if the direction of the current is known. Right hand rule: Hold your hand along the nail with the thumb up. If the curl of your fingers represent the direction of flow of current, the thumb represents the north pole.

Generating Electricity Faraday's Law: Electric force is generated due to a changing Magnetic -field through a conducting coil, also called principle of induction. Moving magnet, stationary coil Moving coil, stationary magnet

Faraday’s Law Voltage generated proportional to 1.Number of coil turns, N 2.Strength of the magnets 3.change in magnetic field a) Speed of rotation Approximate pull force: over 12 lbs Approximate pull force: over 4.5 lbs Speed= 1 rotation/sec V gen = 8 volts Speed= 2 rotation/sec V gen = 16 volts

Activity: Generate Electricity using Magnets Step 1: Wind the wire around the cardboard box. Step 2: Remove the insulation from the two ends of the wire on the cardboard. Step3: Connect the light bulb to the ends of the wire. Step4: Place the skewer/stick through the box and place the magnets at the center of the box around the skewer/stick. Step5: Rotate the skewer/stick so that the magnets rotate too. Observe the light bulb light up.  Remember, faster the rotation, more the generated electricity.

Motor Converts electrical energy to mechanical energy. Opposite of a generator. Based on the principle of an electromagnet. 8

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