Solenoids | Show Me The Physics

Solenoids lesson illustration

Where is the magnetic field strongest?

Solenoids lesson illustration

Explain what is
happening off camera
to create what you see
in the video below.

When current is on, electromagnet's N pole
attracts the S pole of
compass. When current
is reversed, poles are
reversed.

Electric Bell

Name the major parts of an electric bell.

What is the function of part C?

Electric Bell

Source: Elroy M. Avery School Physics (New York: Sheldon and Company, 1895) 556

| Clipart ETC | Alternate Sizes |

E - Electromagnet, H - Striker, P - Switch

C - When the striker is attracted to the electromagnet, the circuit is opened and the striker returns to its initial position

Click on the picture below
to activate a larger version of this animation

Electric Bell - Flash

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Show Me The Physics

Fill In The Blank Notes

Ex 4) Magnetic field around Solenoid (Electromagnet)

Solenoids lesson illustration

(conductor arranged in a coiled pattern)

North and South Pole
at either end of the core.

3D Solenoid Electromagnet
Change the current, the number of turns, and the core • Drag to rotate • Pinch or scroll to zoom

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1. Determine North and South pole with ...

a) North Pole of a Compass

Solenoids lesson illustration

b) 2nd Left Hand Rule

Why Left and not right??

Step 1 - Current travels from
(-) to (+) terminal

DRAW the direction of the current on the wires

Solenoids lesson illustration

Step 2 - WITH PALMS AWAY, point the fingertips of left hand in direction of current

Solenoids lesson illustration

Step 3 - Thumb - North Pole!!

Solenoids lesson illustration

North Pole - RIGHT or LEFT???

Right

Solenoids lesson illustration

North Pole - Top or Bottom?

Bottom

Solenoids lesson illustration

North Pole - Right or Left?

Left

[ Flash ]

Check Your Understanding

5 quick questions — pick an answer to see if you’re right.

1. A solenoid (electromagnet) is best described as:

2. In the 2nd left-hand rule, the left fingertips point along the current in the coils. What does the thumb point to?

3. In the left-hand rules on this site, which way does the current travel through the wire?

4. The current in an electromagnet is reversed. What happens to a nearby compass that was attracted to its north pole?

5. In an electric bell, what happens right after the electromagnet attracts the striker?

Increasing Magnetic Field Strength →