Introducing 

Prezi AI.

Your new presentation assistant.

Refine, enhance, and tailor your content, source relevant images, and edit visuals quicker than ever before.

Loading…
Transcript

Also...

This leads to...

All this gives us...

As polarity of voltage switches, current direction switches

Let's see it in action...

References:

Olesnicky, A and Lawrence, N 2008. Physics Key Ideas Part 1. 3rd ed., Greg Eather and Adelaide Tuition Centre, Adelaide.

Also, direction of field is direction that north pole of a compass needle points

Always closed loops

Magnetic Fields

Represented by magnetic field lines

Drawn from Magnetic North to Magnetic South

Direction of field at a point is in direction of tangent to the field line at that point

Additional to a charge's electric field

The greater the density, the stronger the field

Field strength represented by density of field lines (number of lines crossing a unit area)

Produced by moving charges (and hence currents).

Static charges do not produce a magnetic field. They only have their associated electric field.

http://newscenter.lbl.gov/2014/08/19/nmr-using-earths-magnetic-field/

https://www.youtube.com /watch?v=a_1XgioXMDw

Moving charge's magnetic field

Note: Video uses different rule to determine the same result for the direction of the force (Fleming's left hand rule)

Due to interaction of external magnetic field with current-carrying conductor's magnetic field

A current-carrying wire produces a magnetic field.

Direction of the magnetic field can be determined using the Right hand curl rule

When placed in a magnetic field, a

current-carrying conductor

experiences a force (F)

Direction of force can be

determined using the

Right-hand palm rule

https://physick.wikispaces.com/Electric+Current

https://www.youtube.com /watch?v=14SmN_7EcGY

Magnetic Force on current carrying conductor

Perpendicular to the field

Perpendicular to the field (from definition of magnetic field strength):

Current element defined as the length of a piece of wire multiplied by the current through the wire:

Three cases for the positioning of the current-carrying conductor in the magnetic field.

Parallel to the field:

Parallel to the field

The definition of the Magnetic Field Strength (B)

B is defined as the Force per unit current element,

where current element is placed at right angles to the field at the point where B is being measured:

Magnetic Field strength unit:

At an angle to the field

Strong permanent magnet at the back

The Moving-coil Loudspeaker

Current-carrying conductor coiled around middle of permanent magnet

The coil and cone are able to move horizontally, forwards and backwards

Speaker cone attached to coiled conductor

Current flows through coil

Permanent magnet produces a Magnetic Force on coil due to the flowing current

Causes coil to move, in-turn moving the speaker cone

When voltage is turned on...

Changes direction of the Magnetic Force on the coil due to the permanent magnet

https://www.youtube.com /watch?v=HGAIPXnBKJE

E.g. If voltage switching at 200Hz,

current switches direction at 200Hz,

changing direction of force at 200Hz,

hence, changing direction of movement of speaker cone at 200Hz

This produces a 200Hz sound

Moving-coil

Loudspeaker in action

http://resources.yesican-science.ca/

Compass showing direction of magnetic field

www.tutorvista.com

Bar magnet

magnetic field

http://onlinephys.com/

Loop

magnetic field

http://www.endesaeduca.com/

Solenoid

magnetic field

Current-carrying wire

magnetic field

When thumb is in the direction of the current,

curled fingers are in the direction of the Magnetic field

http://www.meritnation.com/ask-answer/question/state-the-right-hand-thumb-rule/science/5741943

Right-hand curl rule

Fingers in direction of Field,

Thumb in direction of Current,

then

Palm shows direction of Force

en.wikipedia.org

www.a-levelphysicstutor.com

Different angles of

current-carrying conductor

to magnetic field

This is because for the parallel component, F = 0. Hence, only perpendicular component experiences non-zero force

Current-carrying conductor

at an angle to magnetic field

http://www.electronicshub.org/sound-transducers/

Moving-coil

Loudspeaker

A2: As simple

application of

right-hand curl rule

a) AE1: As analysing data

b) AE1: As again analysing

data

A1: As have to apply concepts

to solve a question in a

new context

Magnetic Fields

By: Fabian Karuga

Learn more about creating dynamic, engaging presentations with Prezi