Unit 5 Magnetism Physics B Bell Work Using

Unit 5: Magnetism Physics B

Bell Work Using the items at your desk, make as many observations as possible about the properties of magnets.

Shape of the Magnetic Field http: //phet. colorado. edu/en/simulation/magnets-and-electromagnets

Properties of Magnets • If you break a magnet into pieces what happens? • If this happens, what does this mean about ‘monopoles’? But, what causes magnetism?

Type 1: Permanent Magnets

1. Properties of Particles with charge Particle Mass Charge Proton Electron Does this mean all matter is magnetic?

2. The Atom Ferromagnetic / Anti-ferromagnetic

www. ptable. com

3. Crystals

4. Domains How do we know the moon use to have a magnetic field?

Bell Work Given this crystal of Cadmium (Cd) and Titanium (Ti), determine if the structure is ferro or anti-ferromagnetic at the atomic and crystal levels.

Type 2: Electro-Magnets

Directions of fields…

https: //www. youtube. com/watch? v=1 TKSf. Ak. WWN 0 Currents create magnetic fields! • Right-hand-rule: Put your thumb in the direction of the current, and your fingers wrap around in the direction of the magnetic field.

Practice I I I

Making currents into looks

B = magnetic field µ = permeability of free space n = number of turns I = current

Geo-dynamo

Magnetic Field App & Gauge Bozons • http: //www. falstad. com/vector 3 dm/

• https: //www. youtube. com/watch? v=p. Pn. Gvjm. Ig. ZA

Quantifying Magnetism •

New Right-hand Rule…

Practice! • A proton moving east experiences a force of 8. 8 x 1019 N upward due to the Earth’s magnetic field. At this location, the field has a magnitude of 5. 5 x 10 -5 T to the north. Find the velocity of the particle.

A charge moving through a magnetic field follows a circular path…

Another Thought: B v l Q • A wire, with a charge Q lays in a magnetic field pointed out of the page… • If the wire is physically moved to the left… • The force is in the _______ direction. • What does this mean?

Since there’s a force…. •

EMF: Electromotive Force •

New Problem • A wire, with 6 Ω of resistance, and 12 m of length, sits in a magnetic field of 2 T in the same position as the previous example. Calculate the magnitude of the current. • Note: Recall Ohm’s Law

Bell Work 1. Given the setup to the left, does a current flow through the wire? 2. Given the initial conditions: - v = 5 m/s - length = 5 m - the work done on each charge due the magnetic field is 9 V Determine the strength of the magnetic field.

Magnetic Force on a current carrying conductor…

Practice • A wire 36 m long carries a current of 22 A from east to west. If the magnetic force on the wire due to Earth’s magnetic field is downward (towards Earth) and has a magnitude of 0. 04 N, find the magnitude and direction of the magnetic field at this location.

Note… •

In the event of two wires, creating their own magnetic fields, and exposing each other to those fields…. I I

Two parallel wires A. Currents flowing in the same direction. Will the wires attract or repel? B. Currents flowing in the opposite direction. Will the wires attract or repel?

Changing Magnetic Fields generate currents… • https: //www. youtube. com/watch? v=txm. Kr 69 j. GBk https: //www. youtube. com/watch? v=Nqd. Oyx. JZj 0 U

Magnetic Induction •

So changes to flux occur when: • The area the field goes through changes. • An area is exposed to a magnetic field or magnetic field strength changes. • The angle the loops is in the magnetic field changes.

Example 1: Changing Area

Example 2: Magnetic Field Strength Changes

Example 3: Changing Angle

Applications of the concepts…

Transformers

Recap http: //sdsuphysics. org/Natural. Science 100/Topics/3 Mind/3 magne tism_induction. html