Magnetic Fields
- Created by: Jasmin
- Created on: 06-05-13 14:37
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- Magnetic Fields
- A magnetic field is a region where magnetic materials (iron, steel) and also wires carrying currents experience a force acting on them
- Arrows on field line always north to south
- When current flows through a wire, magnetic field created around the wire
- Thumb: current Fingers: magnetic field
- An electromagnet is made of insulated wire wrapped around an iron bar (the core)
- Magnetic field from wire magnetises iron bar
- Current switched off, iron bar loses magnetism
- Steel is unsuitable as keeps magnetism when current is switched off
- Examples
- Scrapyard crane: used for lifting steel and iron
- Steel frame of vehicle sticks to electromagnet when current passes through coil
- Current switched off, steel frame drops off electromagnet
- Steel frame of vehicle sticks to electromagnet when current passes through coil
- Circuit breaker
- Switch held in place by iron catch
- Too much current, witch pulled open by electromagnet, switch opend
- Stays open till reset manually
- Too much current, witch pulled open by electromagnet, switch opend
- Switch held in place by iron catch
- Electric bell
- Bell connected to battery, iron aarmature pulled onto electromagnet
- Opens the make - and - break switch and electromagnet switched off
- Armature springs back and the make - and - break switch closes again
- Cycle repeats itself
- Armature springs back and the make - and - break switch closes again
- Opens the make - and - break switch and electromagnet switched off
- Bell connected to battery, iron aarmature pulled onto electromagnet
- Relay - used to switch electric machine on/off
- Current passes through electromagnet, armature pulled onto electromagnet
- Armature turns about the pivot and closes the switch gap
- Current passes through electromagnet, armature pulled onto electromagnet
- Scrapyard crane: used for lifting steel and iron
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