Lakshmi GopiReddy

Adventures in STEM

Electromagnetism

Magnets

Magnetic field flows from North to South in almost circular fashion

Activity 1Connect 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?

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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 ElectricityFaraday's Law: Electric force is generated due to a changing Magnetic -field through a conducting coil, also called principle of induction.

Moving magnet, stationary coilMoving coil, stationary magnet

Faraday’s Law• Voltage generated

proportional to1. 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/secVgen= 8 volts

Speed= 2 rotation/secVgen= 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.

MotorConverts electrical energy to mechanical energy.Opposite of a generator.Based on the principle of an electromagnet.

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https://dlnmh9ip6v2uc.cloudfront.net/assets/1/d/4/3/f/525d9258757b7f557c8b4567.gifhttps://learn.sparkfun.com/tutorials/motors-and-selecting-the-right-one/all