Electricity and circuits -SP 10 Flashcards
what direction does convectional current flow in?
conventional current direction goes from the positive terminal to the negative terminal of the battery
how does a metal conduct electricity?
electrons can be easily removed so a metal wire has many ‘free electrons’ when a battery is attached to the wire the voltage ‘pushes’ the free electrons around the circuit.
why do electrons travel along the conventional direction of current?
negatively charged electrons attracted to positive terminal
what are circuit diagrams used to show
components and the junctions in a circuit
What does it mean if components in a circuit are in series?
one route the current can take around the circuit - so if one component fails the circuit currnt will stop
what does it mean if components in a circuit are connected in paralell?
junctions allow the current to take different routes - so each component can be switched on seperatly / there are alternate current routes so if one fails the current will take the alternate route
what unit is electrical current measured in?
amperes / amps
how can amps be measured?
using an ammeter
Why does the total amount of current stay the same in the circuit? what happens in parallel circuits?
the current is conserved - in parallel, the current splits at a junction to travel along different branches - howvere the total amount entering the junction is the same as the amount leaving
if i have a parallel circuit and there are 10 amps going in, how many amps will flow through one path at a junction? how will this change as the current reaches the negative terminal?
5 amps
10 amps
why is a potential difference needed in a current?
to push around an electric circuit
what is another word for potential difference in a circuit?
voltage
how does movement of electrons change when a potential difference is applied across a component?
the bigger the potential difference, the quicker the flow of electrons
what is potential difference measured in?
volts
What conditions must there be for a current to flow?
circuit must be closed and contain a source of potential difference
what is electrical charge measured in?
coulombs (C)
what is potential difference? how can it be descibed?
pushing power causing electrons to move (slope analogy)
what does potential difference do to a circuit in closed system?
causes a current to flow
how is a voltmeter connected to a circuit?
in parallel with component of interest
what is the rule for current in a series circuit?
it is the same everywhere
what is the rule for voltage in a series circuit?
voltage is shared by components
what is the rule for current in a parallel circuit?
current is conserved at junctions
(total current entering a junction equals the total current leaving the junction)
what is the rule for voltage in a parallel circuit?
voltage is the same on each ‘branch’
what is the rule for potential difference in a series circuit?
shared between components
what is the rule for potential difference in a parallel circuit?
the potential difference across each branch is the same as at the supply
what is electrical current?
flow of electrons/ amount of charge passing each second
what equation shows how current is conserved at a junction?
A1=A2+A3
what component does a directly proportional graph show for?
fixed resistor
current induced is directly proportional to the potential difference across it - resistance maintains the same
what component does the directly proportional graph (WITH CURVY ENDS) show for?
bulb
describe the filament lamp graph?
current increases with increasing potential difference but a decreasing rate
the more current there is, the hotter the lamp becomes - resistance increases as a result
what component does the flat line with an upwards tail show for?
diode
explain the diode graph?
diode ha very high resistance in one direction and very little in the other - this means current can flow in one direction
What does an LDR do?
senses light, acts as a light resistor (resistance increases as light decreases
what does a thermistor do?
uses temperature and acts as a temperature sensor (resistance increases as temp decreases)
