Basically on the AQA past paper it says:
The resistance of the metal filament inside the bulb increases as the potential difference across the bulb increases.
Explain why.
My answer:
The increased potential difference means an increased current will flow through the metal filament, as it does, some of the electrical energy is transferred to heat energy which heats up the metal filament and makes the metal ions vibrate faster making it more difficult for the electrical charge to flow through, therefore the resistance increases.
AQA Mark scheme:
metals contain free electrons (and 1
ions)
as temperature of filament increases 1
ions vibrate faster / with a bigger
amplitude
electrons collide more (frequently) 1
with the ions
or
(drift) velocity of electrons
decreases
Would i get it wrong for my answer? Ive learnt that from the AQA approved books!?! Please help and give me advice on this!!!