elec Flashcards
Current
how much charge goes past a point every second
voltage
energy change of an electron
power
the amount of energy a circuit component transforms each second
EMF meaning
max voltage of a battery with no internal resistance
Kirchhoffs voltage law
the sum of all voltages around a closed loop add up to 0
What is a capacitor
A capacitor is a two-terminal electrical device that can store energy in the form of an electric charge. It consists of two electrical conductors that are separated by a distance. measured in Farads F
how to max capacitance
increase area so more charge can flow onto plates, decrease distance, add a dielectric material
Charging and discharging capacitors
resistor voltage starts at source voltage and capacitor voltage starts at 0. they swap.
capacitor time constant
the amount of time that it takes for the curve to either rise or fall by 63%. after about 5 time constants have passed, the charging or discharging is complete.
electromagnetic induction
if a wire moves through a magnetic field not parallel
faradays law
if you change magnetic flux you get an induced voltage
magnetic flux
symbol Φ and unit webber Wb. tells us how much of the magnetic field is passing through the area inside the loop of our circuit
Lenz law
the change in flux induces a voltage which forces a current. the new current will make a new magnetic field. the new field opposes the change in flux of the first. this is why there is a - in the induced voltage equation
mutual inductance
a changing current in one coil produces a changing flux in another separate coil and induces a voltage in that other coil
transformers
rely on mutual inductance when the changing current (in primary coil) is AC. If Np/Ns > 1 is a step up transformer so the induced voltage in the secondary coil is bigger. If Np/Ns < 1 it is a step down transformer as the induced voltage in the secondary coil is smaller. The power of coil 1 ( the energy transferred) is equal to the power of coil 2 (the energy received).
