electricity Flashcards
what is a conductor
a material that allows easy flow of electrons
what is an insulator
a material that prevents electron flow and blocks electricity
what are semiconductors
materials that allow limited electrical flow due to containing fewer free electrons
what is voltage
energy per charge
- work done as charge moves from one potential to another within an electrical field
w / q
what is current
the amount of charge that flows past a point in a unit of time
I = Q / t
what is resistance
opposition of current
V / I
what is conductance and its equation
- the reciprocal of resistance
G = 1/R
what is a ground
a large conductor that is physically connected to the earth
what is convectional current
direction of positive terminal to negative terminal of current flow
what are ohms laws
relationships between voltage, current and resistance
V = IR (rearrange when needed)
what is energy
the ability to do work
- measured in joules (J)
what is power
the rate at which energy is used
- measured in watts
what is the calculation for power
p= IV
= I^2 x R
= V62 / R
how to calculate efficiency
power output / power input
what is charge
an electrical property that exists because of an excess / deficiency of electrons
what is conductance
the ability of a circuit to allow current
what is an ampere-hour rating
current x time
- discover how long a battery can deliver current to a load
what is an inductor
a coil of wire around a source that oppose a change in current
what is the calculation for inductance
Vinds = L x di/dt
L = inductanace of coil
di/dt = time rate change of current
what is the calculation of the energy stored in an inductor
w = 1/2 x L x I^2
what is DC current
direct current
- when magnitudes of the volatge & current are constant
- polarity of DC voltage source does not change
- current flows in one direction only without reversing
what is AC Current
Alternating Current
- magnitude of both voltage and current vary in a repetitive manner, typically following a sine wave
- polarity of voltage source and direction of Q changes periodically, reversing direction overtime
what is amplitude of a sinusoidal (sine) wave
maximum value of voltage / current
what is period of a sinusoidal (sine) wave
time interval for one complete cycle
what is frequency
the number of cycles that a sine wave completes in one second
how is a sinusoidal wave generated in AC
when a conductor rotates in a constant magnetic field
- rotational energy is converted to electrical energy
