electric circuits Flashcards
long rectangle shape..
resistor
play button..
diode
allows current in one direction
play button w arrows…
LED, emits light
what is charge measured in
coolombs (c)
what determines the size of current
rate of the flow of the charge
a current of 1A=
1c of charge per sec
charge equation
charge flow (q) = current (I) x time (t)
what is a battery
two or more cellls connected together
what direction does current flow
pos to neg
what is a current
flow of charge around a circuit
what is cahrges symbol
Q
resistence?
how much energy required to push a coolomb of charge
potential dif equation
potential dif = current x resistence
whats resietcne measyred in
ohms
what is potential dif
energy transferred per coulomb of charge
or the force that drives electrons around the circuit
potential dif equation
V = I x R
OR E = V x Q
potential dif in parralel circuits..
some for all components
explain required practical resistence
so you have a long wire attached to a circuit and clipped onto a ruler and the clips can slide so you can ajust the amount on the circuit. the length of the wire is proportional to the resistence
how to stop a zero error and why there is one in required practical resistnce
the clip is very hard to get actually at zero and theres a small resistence between the clip and the wire. zero error means the value should be at zero but isnt and wont be so youve got to subtract the zero error
temp issue in required prac resistence
temp is porpotional so can increase it, so you want to make sure you maintain a low pd which willl lower the current and stop any heat. you can do this with a variable resistor which controls the amount of current
explain practical components and resistence
to see if the resistence depends on the current in dif components. measure potential dif and current as normal and then use the variable resistor to change the current and coninue to make note. also flip the cell to change direction of current. repeat
fialment lamp results
as the current increases its temperature increases and atoms vibrate more increasing the resistence, same with any metal. so its graph is fast and then slows to a halt.
resistence increases as temp increases as its a metal
diode results
diode needs an etxra resistor as it i very sensitive to strong currents. in the reverse its resistence is so high it does not have any current and in the normal it takes until 0.6v for the current to raise
resietnce is very low one way and too high the other
what happens to LDRs and thermistors ressitence when the temp/light increases
they are not metal and it decreases
properties of series
current is the same evrywhere
total pd is shared between components
total resistence is shared between compoents
what do resistors do
limit the current
properties of a parralel
current is shared begtween loops
all PD is the same
bigger the resistence..
less current will pass through
adding more resistence/ components..
decreases the total resistence which may seem weird but its like the pd will always be the same so if you add more it will increase the current entering and resistor is basically pd divided by current.
what do diodes do
like valves, only allow flow in one direction
energy equations
E = P x T
E = V x Q
E= V x I x T
power equations
P = E/T
P= I x V
P= I2 x R
what is charge
current flowing through in a period of time
