Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    0
    ReputationRep:
    heya, I was just revising for As physics and though of a question I couldnt answer. (Its not an exam question more a query)

    Does the photoelectric effect mean metals conduct electricity worse when it is dark?

    If anyone could help answer this it would be great x
    Offline

    3
    Interesting question! It really made me think
    Apparently (after a brief bit of googling) yes, but most prominently in certain semiconductors. If you think about a light dependent resistor, its resistance decreases as light intensity increases. As intensity increases, more photons are being absorbed per second, meaning more electrons are given enough energy to become free electrons. This increases the free electron density, reducing the resistance and making the semiconductor a better conductor.
    However, given visible light has little energy due to its lower frequency (compared to gamma rays and so on), I suspect in most metals the phenomenon is considerably reduced - given nearly all wires are insulated, and hence no visible light reaches them, I would assume it doesn't reduce the conductivity of the wires too much!
    This does beg the question of whether a similar decrease in resistance occurs for more metals under gamma radiation... I'd be fascinated if anyone with more knowledge than me could provide and answer or tell me where I've gone wrong here.
    Offline

    17
    ReputationRep:
    (Original post by JustLex)
    heya, I was just revising for As physics and though of a question I couldnt answer. (Its not an exam question more a query)

    Does the photoelectric effect mean metals conduct electricity worse when it is dark?

    If anyone could help answer this it would be great x
    Basically, no. The photoelectric effect demonstrates the particle nature of light (photons). It has nothing to do with conductivity in metals since metals already have lots of electrons in their conduction band
 
 
 
Poll
Do you agree with the PM's proposal to cut tuition fees for some courses?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.