electricity - current Flashcards
(26 cards)
what are examples of components in a circuit
cell, lamp, switch
what will happen in a series circuit if you close the switch
electrons will flow out of the cell and around the circuit
define electric current and give the unit
the flow of electrons around the circuit
ampre
which way does the current flow
from the negative end to the positive end
true or false
electrons carry energy from the cell and pass it onto the components
true
how is the electrical current represented
using an arrow and it is known as the conventional current
which way does the arrow point
opposite from the current, pointing to the positive side to the negative
what makes a circuit a series circuit
it has no branches and the current can only flow in one path
what measures electrical current
an ammeter
what happens to current in a circuit
current is never used up, and in a series circuit it is the same all the way round
what is a parallel circuit
a circuit which has branches
what happens to the current in a parallel circuit
the current splits between the branches and adds up to the total current leaving the cell
what circuit components are used in required practical 4 - current
a battery connected via wire to a resistor, and a variable resistor and ammeter as well as a volt meter in parallel to the resistor
what is step one in this experiment
use the voltmeter to measure the potential difference across the resistor
record these values in a table
step 2
adjust the variable resistor and record the new readings on the voltmeter and ammeter
why do you need to do that several times
to get a range of readings
step 3
with the direction of the battery meaning the direction of the potential difference has reversed
the volt meter and ammeter should have negative readings
next plot a graph to show the current against the potential difference
what should it look like and what does it tell us
a straight line should pass through zero telling us that the current through a resistor is directly proportional to the potential difference
what happens to the graph if you switch the direction of the potential difference
we still get a straight line
what happens to the graph if the resistor gets hot
it won’t have this shape meaning its important to not have the circuit connected for too long
when repeating this experiment, what would you replace the resistor with
a filament lamp
in the case of a filament lamp, what graph do we get and what does this tell us
a two way curve telling us the current is not directly proportional to the potential difference
finally, what else could you use in the circuit instead of a resistor or filament lamp
a diode
when using a diode, why would you also need a resistor
diodes are easily damaged by a high current
