Magnetism Flashcards
Magnetism background
- N and S poles
- Like poles repel
- Opposites attract
- magnetic materials ( iron, cobalt, nickel ) are affected by magnetic fields
- non magnetic materials NOT AFFECTED
Induced magnetism
Only magnetic when placed in a magnetic field
solenoid
-Circuit component
-you can build a solenoid by turning wire around a core (normally iron core)
-used as electromagnet
Magnetic field of a solenoid
-When suddenly flows through solenoid, it behaves as a magnet
-when current is off, it loses its magnetism
Clockwise current
End behaves as the South Pole of a magnet
Anti-clockwise current
End behaves as North Pole
Electric charge
Electron: negative electric charge
Number of electrons (negative charges) balances the number of positive charges in each atom.
Atom gains extra electrons= negatively charges
Atom loses electrons= positively charged
Charge measured in Coulombs (C)
Static electricity
-charge will not flow
-charging by friction (objects can be electrostatically charged by rubbing two surfaces together)
-electrons are transferred by one object to the other
Electric field
Region of space where a charged object experiences an electric force
Electric current
-The rate of flow of charge.
-flows from positive to negative
-measured in amps
Current = charge/time
Direct current (DC)
-current flows in one direction
-constant value
-provided by batteries
Alternating current (AC)
-current changes direction
-values alternate btw + and -
-provided by national grid
Ohm’s law
Resistance = voltage or potential difference (v)/current (A)
Electromotive force: emf
-not a force
-measured in volts
-emf is work done by a source
EMF= Work Done/ Charge
Potential difference (voltage)
=Work Done/ Charge
-potential difference is the Work Done by unit charge passing through a component
