Difference between revisions of "4-ELM-02"
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==[[Specifications|Specification]] References== | ==[[Specifications|Specification]] References== | ||
| + | * 6.11 appreciate that there is a force on a charged particle when it moves in a magnetic field as long as its motion is not parallel to the field''' | ||
| + | * 6.12 recall that a force is exerted on a current-carrying wire in a magnetic field, and how this effect is applied in simple d.c.electric motors and loudspeakers | ||
| + | * 6.13 use the left hand rule to predict the direction of the resulting force when a wire carries a current perpendicular to a magnetic field | ||
| + | * 6.14 recall that the force on a current-carrying conductor in a magnetic field increases with the strength of the field and with the current | ||
| + | ==Starter== | ||
| + | * Show them the wire hanging between the two poles of magnet and switch on current. Let them discuss what happens. | ||
| + | * Reverse polarity, direction of current and let them analyze what happens. | ||
| + | * Have ready one of the little motors and tell them that they will have to be building one themselves | ||
| + | |||
| + | ==Main Body of Lesson== | ||
| + | * Discuss why the wire moves when current is flowing through it: the magnetic field of the permanent magnet reacts with the magnetic field of the current in the wire. | ||
| + | * This interaction between the two magnetic fields is shown by the presence of the electromagnetic force acting on the wire; under the action of the electromagnetic force, the wire moves. | ||
| + | * The direction of the electromagnetic force is given by FLEMING’s LEFT HAND RULE: | ||
| + | **Hold your left hand and spread out the thumb, first and second finger so that they are at right angles to each other. | ||
| + | **Point your First Finger in the direction of the magnetic Field (N to S) | ||
| + | **Rotate your hand about that finger until your seCond finger points in the direction of Current ( + to -) | ||
| + | **THEN thumb points in the direction on the movement of the wire (direction of the electromagnetic force) | ||
| + | |||
| + | * The movement of the current-carrying wire into a magnetic field is called the MOTOR EFFECT. | ||
| + | * Discuss ways in which the turninh effect on the coil/wire could be increased. | ||
| + | * Use the 'electric motor' worksheet(Science Shared area) to show how Fleming’s left hand rule applies. | ||
| + | * Complete the worksheet | ||
| + | * Show them how the moving-coil loudspeaker works and students build their own. | ||
| + | |||
| + | ==Plenary== | ||
| + | * | ||
| + | |||
| + | ==Homework== | ||
| + | * Complete Physics texbook - page 211 Q 1-3, page 213 Q1-3 | ||
| + | |||
| + | =Additional Information= | ||
| + | ===Resources Required=== | ||
| + | * Large Motor demo, small motor demo, Force on a wire demos, Open loudspeaker demo, Making a loudspeaker kit- class practical | ||
| + | |||
| + | ===Textbook References=== | ||
| + | * ''None'' | ||
| + | |||
| + | ===Website References=== | ||
| + | * None | ||
| + | |||
| + | ===Skills Addressed=== | ||
| + | |||
| + | ===Safety/Hazards=== | ||
| + | * With high currents the wires may get hot. | ||
| + | |||
| + | ===Notes=== | ||
| + | * ''None'' | ||
| + | [[Category:Forces & Matter]] | ||
| + | [[Category:Practical skills - Obtaining]] | ||
Latest revision as of 14:08, 20 April 2010
Contents
Specification References
- 6.11 appreciate that there is a force on a charged particle when it moves in a magnetic field as long as its motion is not parallel to the field
- 6.12 recall that a force is exerted on a current-carrying wire in a magnetic field, and how this effect is applied in simple d.c.electric motors and loudspeakers
- 6.13 use the left hand rule to predict the direction of the resulting force when a wire carries a current perpendicular to a magnetic field
- 6.14 recall that the force on a current-carrying conductor in a magnetic field increases with the strength of the field and with the current
Starter
- Show them the wire hanging between the two poles of magnet and switch on current. Let them discuss what happens.
- Reverse polarity, direction of current and let them analyze what happens.
- Have ready one of the little motors and tell them that they will have to be building one themselves
Main Body of Lesson
- Discuss why the wire moves when current is flowing through it: the magnetic field of the permanent magnet reacts with the magnetic field of the current in the wire.
- This interaction between the two magnetic fields is shown by the presence of the electromagnetic force acting on the wire; under the action of the electromagnetic force, the wire moves.
- The direction of the electromagnetic force is given by FLEMING’s LEFT HAND RULE:
- Hold your left hand and spread out the thumb, first and second finger so that they are at right angles to each other.
- Point your First Finger in the direction of the magnetic Field (N to S)
- Rotate your hand about that finger until your seCond finger points in the direction of Current ( + to -)
- THEN thumb points in the direction on the movement of the wire (direction of the electromagnetic force)
- The movement of the current-carrying wire into a magnetic field is called the MOTOR EFFECT.
- Discuss ways in which the turninh effect on the coil/wire could be increased.
- Use the 'electric motor' worksheet(Science Shared area) to show how Fleming’s left hand rule applies.
- Complete the worksheet
- Show them how the moving-coil loudspeaker works and students build their own.
Plenary
Homework
- Complete Physics texbook - page 211 Q 1-3, page 213 Q1-3
Additional Information
Resources Required
- Large Motor demo, small motor demo, Force on a wire demos, Open loudspeaker demo, Making a loudspeaker kit- class practical
Textbook References
- None
Website References
- None
Skills Addressed
Safety/Hazards
- With high currents the wires may get hot.
Notes
- None
