Lesson 3: The Third physics lesson with a native speaker of English
The topic is “Magnetism, Circuits”
- Outward lines
- Inward lines
- Michael Faraday
- Like charges
- Unlike charges
Electric field is a space where charged objects create attraction or repulsion forces. If these are like charges, for example positive and positive, they will repel each other. In case when we have unlike charges, we will observe attraction between them.
As described by Michael Faraday, positive charges have outward lines, and negative charges have inward lines.
- To conduct electricity
- Wire clippers
- Conducting wires
- A bare wire (a wire without insulation)
- A bulb
- To glow
Insulation = isolation – using materials that do not conduct electricity, like plastic, to cover a wire.
Bare wire means uncovered wire, that is, not covered with insulators like plastic.
A short circuit is an electrical circuit that allows a current to travel along an unintended path, often where no (or a very low) electrical resistance is observed. A common type of short circuit occurs when the positive and negative terminals of a battery are connected with a low-resistance conductor, like a wire. With low resistance in the connection, a high current exists, causing the cell to deliver a large amount of energy in a short time.
We may observe how short circuit works in the video. For this experiment we cut a copper wire without insulation into 3 pieces. Connect the battery terminals (negative and positive) to the light bulb with the help of the wires. The bulb glows.
What happens if you take the third piece of bare wire and place it across the circuit? – The bulb will stop glowing. It’s because the light bulb offers more resistance to the flow of current than the bare wire, so the electricity chooses easier way to travel electricity chooses an easier way to flow.
- Bar magnet
- Poles of the magnet: South pole and North pole
- Iron filings
- Iron nails
- To line up
- Soft iron piece
- To stroke (a soft iron piece with a bar magnet)
- To get (become) magnetized
- Lower side
- Upper side
- To turn
- To attract
Take a soft iron piece and stroke it with a magnet bar several times. The upper side of the iron piece will become magnetized. Now, turn the piece and magnetize the lower side of the iron piece in the same manner.
Point A of the iron piece will get the same polarity as the pole of the magnet touching it. This means that: if side A was touched with the negative pole of the magnet, it will get the negative polarity and side B will get the opposite one.
Test for magnetism: place some iron nails (also possible to use iron filings) on the table and bring the magnetized iron piece near the nails. It will attract them.
Special Thanks to Olena Shlap (native speaker of English)