A-LEVEL PHYSICS: YT video: All of AQA Electricity Explained (PhysicsOnlineYOUTUBE) Flashcards
3 basic quantities we are interested in in a-level: (3)
V I R
current:
rate of flow of charge
I = …
I=ΔQ/Δt
basic charge carriers in circuit:
e-
conventional current:
current that flows + to -
despite conventional current, the charge carriers themselves (e-) are actually…
moving - to + terminal
conventional current goes ___ to ___, but the charge carriers (e-) go ___ to ___
+ -, - +
what causes current to arise in the first place in a circuit?
difference in potential between terminals (+ & -)
V = …
V=E/Q
potential difference:
energy transferred per unit charge
in ohmic conductors, I & V are…
directly proportional
resistance:
the ratio of the potential difference across a component divided by the current in that component
R = …
R=V/I
ammeter goes in ___, voltmeter goes in ___
series, parallel
ammeter measures…
current in series component
voltmeter measures…
potential difference between 2 points in a circuit across a component (parallel)
I-V graphs for ohmic conductors:
straight line through the origin (directly proportional)
filament lamps are…
non-ohmic conductors
diodes enable:
current to flow in only one direction
if you want to measure the resistance of a piece of wire, it depends on the…
why?
length
bc when longer, there’s more obstacles that the e- may collide with
if you have a piece of wire twice as long, it will have…
twice the resistance
why does the resistance of wire depend on length?
bc when longer, there’s more obstacles that the e- may collide with
if we had a thicker wire (bigger ___), there’s more pathways for the ___ ___ (___) to move
C-S.A., charge carriers, e-
resistivity equation:
R=ρ L/A
