H - Electronics Flashcards
one coloumb is the combined charge of how many electrons
6.241 x 10 to the power of 18
Name examples of insulators
rubber
plastic
ceramics
air
dry paper
pure water
wood
what is the SI unit of voltage and what is it measured in
voltage (V) is measured in Volts (V)
what are capacitors
the terminal electronic component that stores electrical energy in an electric field
what is the difference between conventional and actual current flow
electrons flow from negative to positive points in a circuit in actuality, due to their negative charge, but this is the other way round in conventional current flow.
Define ‘joule’
DEF:
the SI unit of work or energy, equal to the work done by a force of one newton when it’s point of application moves one meter in the direction of action of the force, equivalent to one 3600th of a watt-hour
what happens when a capacitor is connected to an AC supply, with a low frequency
the capacitor will have enough time to charge in one direction, and the opposition to current flow will be high
what is the SI unit of resistance and what is it measured in
resistance (R) is measured in ohms (Ω)
name examples of semi-conductors
carbon
silicon
germanium
what happens to the low frequencies across the capacitor in an LCR circuit
the low frequencies drop across it, and create a low pass filter
what is the SI unit of time constant
τ (tau)
what does a transducer do
converts one type of energy into another one
what is the difference between balanced and unbalanced audio
unbalanced cables carry a ground wire, balanced cables carry 2 copies of the same signal which are reversed and phase flipped.
what is the SI unit of power and what is it measured in
power (P) is measured in Watts (W)
what is impedance matching
when source output (source) equals source input (load), and maximum power is transferred.
what is an LR circuit
an inductor and a resistor in circuit series
how much is the cutoff frequency attenuated by in dB
3 dB
what is the rule of thumb for impedance briding
low output (source) should meet high input (load) impedances
Define power.
What is the unit of measurement used?
DEF: the rate of work done over time or the rate of using energy.
measured in watts (W)
the more a capacitor is charged, the higher the….
opposition to current flow
define ohms law
current is directly proportional to voltage and indirectly proportional to resistance
what is the output across the resistor in a CR circuit
a high pass filter
what are inductors, and what does inductance do
An inductor is simply a coil of wire. When current passes through the coil, an electrical field is generated. The field has been “induced.” The bigger the coil or the greater the number of turns, the greater the induced field. This phenomenon is called “inductance.”
How many joules are in 1 Watt?
1 W = 1 joule per second
What determines the amount of charge that can be held by a capacitor?
size of plates, distance between them and the material used for the dielectric
what happens to the mid frequencies across the resistor in an LCR circuit
the mid frequencies will drop across it, and create a band pass filter
what is current
the rate of flow of electrons, and describes the number of electrons that pass a point per second
what is reactance
it is the opposition to a circuit element to a change in current or voltage, due to that elements inductance or capacitance. It is a frequency dependent opposition
what is the output across the inductor in a LR circuit
a high pass filter
what do transformers do
they bring the voltage up or down, and they only work with AC
what is a capacitors time constant
the time constant determines the time it takes the capacitor to charge
What does the frequency of AC reflect?
how many times in a second the current changes direction
How does a capacitor store charge?
when connected to an electric circuit one plate attracts electrons and one repels them, leading to a buildup of positive charge on one plate and an equal negative charge on the other.
What kind of electricity is used by most of our devices?
DC
how would you describe electricity
a form of energy resulting from the existence of particles either statically as an accumulation of charge or dynamically as a current.