Block 2 Part 1

Magnetism

The force that attracts or repels certain types of metals

Permeable

The ability of a material to become magnetized

Ex: Iron, Nickel Steel

Retentivity

A materials ability to hold a magnetic field or magnetism

Flux Lines

invisible lines that form a magnetic field around a magnet ( North to South )

Electromagnetism

Current flowing through a wire creating a magnetic field

Left hand rule

thumb is direction of current flow and fingers point towards flux lines

• No flux in open circuit and flux in closed curcuit

Strength of Magnetic Fields

1. Number of Coils

2. Distance

3. Current

4. Core

Electromagnets examples

1. Relays

2. Circuit Breakers

3. Meters

Measuring Resistance

1. Measure opposition to current flow

2. No power applied

Measuring Voltage

1. Measure difference of potential

2. Power must be applied

Measuring Current

1. Must be placed inside circuit

2. Not energized when placed, then energized

3. Only positive lead is charged

Multimeter Characteristics

• Positive lead= Red

• Black Lead = Common

Magnetism Characteristics

• North to South

• Two norths repel each other / N and South Attract

Relay

Uses a coil/electricity to control a magnet to control a switch

More flux lines equals

Stronger magnetic field

What materials are affected by flux lines

Steel, Nickel, Iron

Permeable Metals

The arm used in a relay or switch

Magnetic

Electromagnetic device measures values in a circuit

Meter

What component prevents excessive current in a circuit

Circuit breaker

Needle on an analog meter is moved by

Electromagnetism