M4 Electricity & Magnetism Flashcards
attract
what two unlike charges do
battery
the power source in a circuit made up of two or more cells
break
an interruption in the flow of electricity
cell
a single electrical energy source which uses chemical reactions to produce current
circuit
a path through which electric current can flow
closed circuit
an electric circuit through which current can flow without interruption
Coulomb’s Law
the relationship between two charges
F =(1/4πε0_) x
(q1q2/r²)
current
the flow of electric charge (q)
current unit is ampere (A)
earth
the reference point from which voltages are measured
electrical condutor
a material that allows electricity to flow through it eg metals
electrical insulator
a material which does not allow electricity to flow through it eg wood
electric permittivity constant
ε₀, epsilon naught, is the electric permittivity constant, that is the
permittivity of free space
= 8.854 x 10⁻¹² A²s⁴kg⁻¹m⁻³
electricity
energy that comes from the flow of charged particles
electromotive force
a source of energy that can cause a current to flow in an electrical circuit
ferromagnetic
materials such as iron, cobalt and nickel that are more magnetic than other materials
globe/bulb
an electrical component which lights up in a circuit
leads
the wires used to join electrical componenets
magnetic field
a region near a magnet where a force acts on magnetic materials
mains electricity
electricity supplied for use in homes and businesses
motor
an electrical component which rotates causing something to turn
non-ohmic conductor
a conductor which does not obey Ohm’s law (a globe)
Ohm’s Law
the relationship between voltage and current in an ohmic device
- V=IR
ohmic conductor
a conductor which obeys Ohm’s Law
open circuit
a break in a circuit
parallel circuit
a circuit in which electric current flows through more than one series circuit
permanent magnet
a magnet that creates its own permanent magnetic field
permeability
a measure of the ability of a material to alter the magnetic field in the area that it is in
potential difference (voltage)
the difference in potential between two points
power source
a source of electrical power eg battery, mains etc
repel
what two like charges do
- a force that pushes an object away
series circuit
a simple circular path in which electric current flows only one way through each part
solenoid
a cylindrical coil of wire which when current passes through it produces a magnetic field
static electricity
the build-up of electrical charges on a surface eg rubbing shoes on carpet
switch
a device which can control the flow of electricity
symbol
a symbol used to represent an electrical component
terminals
the parts of a battery that need to be connected in the circuit
voltage
the amount of potential energy between two points on a circuit
- one point has more charge than another
- this difference in charge (between two points) is voltage
TBCHANGED - QUESTION ABOUT HEAT IN ELECTRIC CURRENTS FROM TEST2
When an electric current passes through a metal, heat is produced as the ions in the metallic lattice vibrate with greater amplitude. This increases the chance of a collision of a free electron with an ion in the lattice.
1 mA…?
milliamp, 1 x 10⁻³ A
1 μA…?
microamp, 1 x 10⁻⁶ A
Electric fields are represented by field lines that abide by…
- field lines never cross each other
- field liens are perpendicular to metal surfaces
- the direction of the field lines is given by the direction of the force acting on a proton (in the field)
ammeters!
- go in series
- low resistance so it doesn’t add significant resistance to circuit
voltmeters!
- parallel across a component
- high resistance so it doesn’t take significant current
Across, Through Resistors?
voltage across a resistor
current through a resistor
1 kΩ…?
kilo Ohm, 1000Ω
1 MΩ…?
mega Ohm, 1 000 000Ω
Kirchhoff’s Current Law
current in = current out
At any junction in a circuit, the sum of the currents arriving at the junction is the same as the sum of the currents leaving the junction (current is conserved)
- if this wasn’t the case, there would be a build up of electrons at that junction (creating charge from nothing) and that is impossible
Kirchhoff’s Voltage Law
in any closed loop circuit, the total voltage around the loop is equal to the sum of all the voltage drops within the same loop (which is also equal to 0)
explain the right hand grip rule
- gives the direction of magnetic field
a dot is current out of page
a cross is current into page
thumb is direction of conventional current, direction of fingers is direction of magnetic field lines
right hand coil rule
- gives the direction of a magnetic field due to the solenoid
fingers curl in direction of the current in the coil,
the thumb points in direction of North Pole (end of coil)
