How to work out resistance
R = V/I
Define current
The rate of flow of charge where charge is the flow of electrons
whats current measured in
amps
How to work out charge
Q (Charge(Coulombs)) = I x T (time(seconds))
how do you convert milliamps into amps?
(Your mA) x 10^-3
in parallel what rules does current follow
IT = I1 + I2 + I3
the resistance of a filament bulb ________ with potential difference.
increases
How to work out voltage
V = E/Q
define Potential difference
the electrical energy carried per unit charge
in parallel what rules does P.D follow
VT = V1 = V2 = V3
You have a coil of wire connected to a battery at both ends and an ammeter across the circuit and a voltmeter across the coil of wire. the coil is dipped in water, why?
to keep the temperature constant.
How do you calculate the total resistance of two resistors in series?
add the resistance of both of the resistors together.
RT = R1 + R2 + R3
name 4 factors that may effect the resistance of a wire
the metal used, the current flowing through it, the length of a wire, and the cross-sectional area.
What is charge measured in
coulombs
in series what rules does P.D follow
VT = V1 + V2+V3
in parallel what rules does resistance follow
RT = R1 + R2 + R3
why does the resistance of a filament bulb increase with potential difference.
it’s non-ohmic. current increases - flow of electrons increases - more collisions of electrons with atoms increase. atoms vibrate (increase K.E) increase temp.
in series what rules does resistance follow
RT = 1/R1 + 1/R2 + 1/R3
how to work out power
P =V x I
How do you calculate the total resistance of two resistors in parallel?
RT = 1/R1 + 1/R2 + 1/R3
what is ohms law
The potential difference across a conductor is directly proportional to the current through it.
Total resistance in a parallel circuit will always be ______ than the lowest resistor
less
in series what rules does current follow
IT = I1 = I2 = I3
describe the effect a variable resistor and a diode has on the current?
a diode can only change between a very high resistance (going backwards) and a very low resistance (going forwards). the variable resistor can make more subtle changes.
