When a battery, wires, a bulb, and a switch join in one closed loop, electricity flows and the bulb lights.
Series bulbs all go dark if one fails, but parallel ones stay lit alone, like home outlets.
A coil on a nail becomes an electromagnet, stronger with more turns and off when current stops.
Turn the switch, pick series or parallel, and change the coil turns and the bulb and the magnet come into view.
Use batteries only, and do not touch the wall outlet.
Electric Circuits — Path of Electricity
If a battery, a bulb, and a switch are not joined in one loop, the bulb stays dark. Finding the break and closing the path is the starting point for reading a circuit. Wiring bulbs in one line and wiring them side by side differ in what happens to the other side when one side goes dark, so you need both joins to make sense of the outlets in a house. Wrap a coil on a nail and send current and a hold on clips appears; wrap the wire and leave the current off and that hold does not show up.
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Electric circuit — battery, wire, bulb, switch
💡 What is an Electric Circuit?
①The path electricity flows through is called a circuit
②Battery → wire → bulb → switch → battery
③If the path is broken, electricity stops
④The switch connects/disconnects the circuit
Series & Parallel Connections
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Series vs parallel bulb connections
In the first picture, turning the switch on fills the bulb yellow and several small dots travel around the wire rectangle. Turning the switch off fades the bulb and those traveling dots disappear. In the second picture, series puts 3 bulbs on one wire in a line, and parallel hangs 3 bulbs as branches between a top and bottom wire. Those bulbs do not switch to a dark drawing; the caption underneath writes the difference between one-line joining and side-by-side joining. In the third picture, changing coil turns from 1 to 10 grows the number of loops on the nail, the clip drawings at the lower left grow to at most 5, and the title writes both the turn count and the clip count. The clips are not drawn sliding into the nail.
🔌 Series Connection
①Bulbs in one line
②One off → all off
③More bulbs → dimmer
④Older mini-lights were often series. Many LED decorations today are parallel.
Making an Electromagnet
If wires are drawn, it is easy to believe electricity is already flowing. When the switch is open the path is still in the picture, but the bulb is dark and no dots travel. Another common mix-up is thinking that turning off one of two house outlets kills the other too; if the paths sit side by side, one can be open and the other path stays. Treating a nail with a coil as a magnet at all times is also off. With the same number of turns, the clip count does not grow if there is no current.
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Electromagnet strength vs coil turns
5 turns
🧲 Electromagnet
①Wrap enameled wire (coil) around a nail and pass current — it becomes a magnet
②More turns → stronger
③Cut current → magnetism disappears
④Unlike permanent magnets, you can switch it on/off
Summary
Circuit Components
Battery → Wire → Bulb → Switch (closed loop)
Circuit must be unbroken for current to flow
Connection Comparison
Series: one line (any break stops all) / Parallel: side-by-side (independent)
②Series: one line; any break stops all; more bulbs = dimmer
③Parallel: side by side; independent; same brightness
④Electromagnet: coil + current makes a magnet
⑤The slider changes coil turns only. Stronger current making it stronger is written only.
Examples and Unit Test
Example 1
If one of two bulbs connected in series burns out, what happens to the other bulb?
1
A series connection links bulbs in one line, so current flows along a single path.
2
If one point breaks, the current path is blocked and the other bulb goes out too.
▸ The other bulb goes out as well
In a parallel connection, one bulb going out leaves the others lit. Home outlets are parallel.
Example 2
You make an electromagnet by winding a coil on a nail and passing current. How do you make it stronger, and how does it differ from a permanent magnet?
1
Winding more coils or using a stronger current makes the electromagnet stronger.
2
Cutting the current removes its magnetism, so it can be turned on and off, unlike a permanent magnet.
▸ More coil turns or stronger current / its magnetism disappears when the current stops
An electromagnet makes a magnet from current, so its strength and on/off can be controlled.
Unit-test style
Which statement about electric circuits is correct?
①In a parallel connection, all bulbs go out if one goes out
②An electromagnet loses its magnetism when the current stops
③Current flows even if the circuit is broken in the middle
④In a series connection, more bulbs make it brighter
⑤An electromagnet gets stronger with fewer coil turns
▸ ② An electromagnet loses its magnetism when the current stops
1
An electromagnet is magnetic only while current flows, so cutting the current removes its magnetism.
2
In parallel the others stay lit if one goes out (①), no current flows in a broken circuit (③), more bulbs in series make it dimmer (④), and more coil turns make the electromagnet stronger (⑤).