electronics Flashcards
current
rate of flow of charge
p.d.
energy change per coulomb of charge
resistance
opposition to the flow of current
ohms law
voltage is directly proportional to current
potential divider
series circuit where each resistor receives a share of the supply voltage
Wheatstone bridge
two potential dividers connected in parallel with voltmeter in the middle. the potential difference across the voltmeter can be calculated by calculating the voltage across each resistor and potential difference in the potential divider then calculating the difference between the two
power
the electrical energy transferred each second
DC
Current flows in one direction at all times
AC
current changes direction and instantaneous value with time
mains voltage
230V
r.m.s value
root mean square value, the average or declared value of a supply
peak voltage/current
maximum voltage/current in an AC supply
y-gain
a setting on a oscilloscope with controls the voltage per centimetre or division
time base
time per centimetre or division
period
the time it takes a wave to pass a point
frequency
number of waves per second
electromotive force
number of joules of energy available to a coulomb of charge passing through the cell
internal resistance
opposition the the flow of charges through circuits were supply or source
external resistance
opposition to the flow of charges externally to the source
terminal potential difference
p.d that can be measured at the terminals of a source = E-Vlost
lost volts
difference between EMF and Vtpd pd required for current to pass through the source
open circuit
when load resistance is infinite, so no current flows
short circuit
when load resistance is 0 results in very high currents
capacitance
ability of device to store electrical charge. Ratio of charge stored to pd between two conductors
parallel plate capacitor
2 parallel plates connected to power supply both conductors, separated by a distance
work done charging capacitor
negatively charged plate stores electrons and work is done each time a new. electron is placed on the plate
