Electricity -Terms and definitions Flashcards
I=V/R
I = current (A) (V) = voltage (v) R = resistance
Ohm’s law!
Voltage and Wattage
If an electrical appliance says “220v, 45w” on it, this means that when it’s connected to a voltage of 220v, the power is 45w.
Ohm’s Law
The current in a circuit on an electrical component, depends on the voltage and resistance.
Voltage in a series circuit
In a series circuit, voltage SPLITS
Power
Symbol: P
Unit: Watt (w) or J.s^-1
Power measures how fast energy is transformed (work done).
Centripetal Force & Magnetic Field
Fc = F Fc = (mv^2)/r F = Bqv thus (mv^2)/r = Bqv
Electrical Field Strength
Symbol: E
Unit: NxC-1
Electrical Charge
Symbol: q
Unit: Coulomb (c)
Resistance
Symbol: R
Unit: Ohm Ω
Resistance is the ability of an electrical component to OPPOSE THE FLOW OF AN ELECTRICAL CURRENT
F=BIL
F = force (N) B = Magnetic Field Strength (T) I = Current (A) L = effectuve (perpendicular) distance of wire cutting the magnetic field.
Conventional Current
Always goes from positive to negative.
In reality, it is actually negative electrons going from negative to positive.
Resistors in series
Rtotal = R1 + R2 + R3…
P = *E/t
P = power (w) *E = Change in energy (J) t = time (s)
V = BLv
V = Voltage (v) B = Mgnetic Field Strength (T) L = Length (m) v = Velocity (m/s)
dot -Magnetic field
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Force on Moving Charge in Magnetic Field
A charged particle moving inside a magnetic field will experience a force. Use right-hand slap rule.
Force will cause the particle to turn (centripetal force).
Force and Velocity are always at 90°.
NOTE: If charge is negative, thumb should point in opposite direction due to conventional current.
Lenz Law
The direction of this current/voltage will be such that it will create a force to work against the movement.
Parallel circuit
When there is more than 1 pathway for electricity to go through
F = Bqv
F = Force (N) B = Magnetic Field Strength (T) q = charge (c) v = velocity (m/s)
v=E/q (=change in)
v = Voltage *E = Energy (gained or lost) (J) q = charge (c)
Current in a Parallel Circuit
In a parallel circuit, the current SPLITS
Charge
symbol: q
units: coulomb (c)
def
F=E.q
F = force (N) E = Electrical Field Strength (N.C^-1) q = charge (c)
Current in a series circuit
In a series circuit, current STAYS THE SAME
B = (KI)/d
B = Magnetic field strength (T) I = current (A) d = distance to current (m) k = constant number: 2.0x10^-2T.M.A
Voltage
symbol: V
Is also called the ‘potential difference’.
It is the amount of electrical potential energy one coulomb of charge gains or losses across an electrical current.
Magnetic Field
Has two poles (North and South). Magnetic field lines travel from NORTH to SOUTH
The lines do not cross eachother
Magnetic field strength is represented by the lines. Small gaps (tight spacing)= strong magnetic field Large gaps (lose spacing)= weak magnetic field
Symbol: B
Unit: T (Tesla)
Ammeter
Symbol: A
An ammeter has zero resistance
Because of this, the ammeter goes within the circuit, not attached in parallel.
Electromagnet
A solenoid (densely wounded coil of wire) that creates a magnetic field when current is added. Sometimes an iron core is added to strengthen the magnetic field.
Series Circuit
When there is only one pathway for electricity to go through
P = VI
P = Power (w) V = voltage (v) I = current (A)
Current
Symbol: I
Is how many coulombs of charge pass through a point in 1 second.
Voltmeter
Symbol: v
A voltmeter has infinite resistance
Because of this, the voltmeter must go parallel to the circuit, not within it.
Positive Charge
In direction of force
Negative Charge
Opposite direction of force
Resistors in parallel
1/Rtotal = 1/R1 + 1/R2 + 1/R3 …
Faraday’s Law
When a wire is moving through a magnetic field, a voltage/current will be induced
X -Magnetic field
Going into the page
Right-hand slap rule
Thumb: Direction of current
Four Fingers: Direction of magnetic field
Palm (slap): Direction of the force
Ep=Eqd
Ep = Electrical potential energy (J) E = Electrical field strength (N.C^-1) q = charge (c) d = distance (m)
P=VI
P = power (w) V = Voltage (v) I = Current (A)
E=V/D
E = Electrical Field Strength (N.C^-1) V = voltage (v) d = distance between two plates (m)
Voltage in a parallel circuit
In a parallel circuit, the voltage STAYS THE SAME
Power
Power measures how fast energy is transformed (work done).
Symbol: P
Unit: Watt (W) or J/s
-The brightness of a lamp is dependant on its power. Bigger power = brighter lamp.
-The heat of a heater dependant on power.
Bigger power = heat up faster.
Right-hand Grab Rule
(To find the direction of the magnetic field around a wire/coil)
- Thumb = direction of current
- 4 fingers = curl in the direction of the magnetic field lines
- GRAB
P=ΔE/t
P = Power (W) ΔE = Change in energy (J) t = time (s) 1W = 1 J/s
Faraday’s Law
When a wire is moving through a magnetic field, a voltage/current will be induced.
Lenz Law
The direction of this current/voltage will be such that it will create a force to work against the movement.
V=BLv
V = Voltage (v) B = Magnetic Field Strength (T) L = Length (cm) v = velocity (m/s)
Attraction of Electric Charges
Unlike charges give negative potential energy (attractive force). uUnlike charges attract one another.
Charging by Conduction
Charging an object by allowing it to come into contact with an object that already has an electrical charge.
Charging by Friction
Two objects rub together and one becomes positivley charged and the other becomes negativley charged
Charging by Induction
Charging and object without direct contact (proximity to nearby object charges neutral object)
Conductors
Materials that allow electric charges to flow through them easily
Coulomb
Unit used to measure quantity of electric charge
Current
A flow of electric through a conductor
Current Electricity
The continuous flow of electrons through a conductor
Direct current
An electrical current that always moves in one direction
Electric circuit
Consists of a voltage source and a continuous conducting path for a current to follow
Electric current
The flow of electric charge electric field force field produced by an electrical charge
Electrical Field
The field around charged particles that exerts a force on other charged particles
Electrical Field lines
A map of an electric field representing the direction of the force that a positive charge would experience
Electric flux
The product of a surface area and the component of the electric field perpendicular to the surface
Electric generator
A mechanical device that uses wire loops rotating in a magnetic field to generate electricity
Electric Potential
The difference in electrical charge between two points in a circuit expressed in volts (aka potential difference)
Electrical potential energy
Potential energy due to the position of charge near or other charges
Electrical conductors
Materials that have electrons that are free to move throughout the material; for example, metals
Electrical energy
A form of energy from electromagnetic interactions
Electrical Force
A fundamental force that results from the interaction of electrical charge
Electrical insulators
Electrical nonconductors, or materials that obstruct the flow of electric current
Electrical resistance
The property of opposing or reducing electric current
Electrolyte
Water solution of ionic substances that conducts an electric current
Electromagnet
A magnet formed by a solenoid that can be turned on and off by turning the current on and off
Electromagnetic force
One of four fundamental forces; the force of attraction or repulsion between two charge particles
Electromagnetic induction
Process in which current is induced by moving a loop of wire in a magnetic field or by changing the magnetic field
Electron current
Opposite to conventional current; electron current flows from the negative terminal to the positive terminal
Electrostatic charge
An accumulated electric charge on an object from a surplus or deficiency of electrons
Magnetic Dipole
Magnet with two poles (North & South); all magnets are dipoles; cutting one in half creates two dipoles
Magnetic Field Lines
Invisible lines that map out the magnetic field around a magnet
Magnetic Flux
The lines of force surrounding a permanent magnet or moving charged particle
Magnetic Forces
Forces that may attract or repel without touching
Ferromagnetic Materials
Iron, cobalt, nickel
Magnetic Poles
The ends, or sides, of a magnet about which the force of magnetic attraction seems to be concentrated
Magnetic Reversal
The flipping of polarity of the earth’s magnetic field
Magnetism
The force of repulsion (pushing) or attraction (pulling) between poles of magnets
Negative electric charge
One of the two types of electric charge; repels other negative charges and attracts positive charges
Ohm
Unit of resistance equivalent to volts/amps
Ohm’s Law
The lat that states that resistance is equal to voltage divided by current (R=VI)
Positive Electric charge
One of the two types of electric charge; repels other positive charges and attracts negative charges
Power
The rate of doing work is called power
Power dissipated by a Resistor
P=IV=I^2R=V^2/R
Repulsion of Electric Charges
Like charges give positive potential energy (repulsive force). Like charges repel one another.
Resistance
A material’s opposition to the flow of electric current, measured in ohms
Resistors
Objects that allow charge to flow at a reduced rate (change into heat or light)
Solenoid
A cylindrical coil of wire that becomes electromagnetic when a current runs through it
Superconductors
Some materials in which, under certain conditions, the electrical resistance approaches zero
Voltage drop
The electrical potential difference across a resistor or other part of a circuit that consumes power
