Turn on thread page Beta
    • Thread Starter
    Offline

    3
    ReputationRep:
    Could someone explain to me how QV=hf can be derived from W=Ephoton?

    Thanks
    Offline

    16
    ReputationRep:
    QV=hf gives you the maximum possible energy the photon can give to an electron, assuming this topic involves excitation?
    • Thread Starter
    Offline

    3
    ReputationRep:
    (Original post by Radioactivedecay)
    QV=hf gives you the maximum possible energy the photon can give to an electron, assuming this topic involves excitation?
    I think so? It's about LEDs. I have a graph of switch on voltage against frequency and I have to derive Planck's constant from it. I get that the I can derive it from 'gradient x charge of an electron' but I don't get the first step. How does it give me the maximum energy?
    • Thread Starter
    Offline

    3
    ReputationRep:
    Oh never mind. I think I got it now
    Offline

    9
    ReputationRep:
    Name:  Untitled.png
Views: 22
Size:  214.1 KB


    Can any of you explain this question to me because I have no idea what to do here thanks.
    Offline

    5
    ReputationRep:
    (Original post by Hey234)
    Name:  Untitled.png
Views: 22
Size:  214.1 KB


    Can any of you explain this question to me because I have no idea what to do here thanks.

    Straight out of course notes.
    The gradient of the graph = -r, where r is internal resistance of the battery.
    Extend the line with a ruler til it touches the axes. The y-axis intercept i the emf, the x-axis intercept is the sshort-circuit current, which is what the question asks for.
 
 
 

University open days

  1. University of Bradford
    University-wide Postgraduate
    Wed, 25 Jul '18
  2. University of Buckingham
    Psychology Taster Tutorial Undergraduate
    Wed, 25 Jul '18
  3. Bournemouth University
    Clearing Campus Visit Undergraduate
    Wed, 1 Aug '18
Poll
How are you feeling in the run-up to Results Day 2018?
Applying to university
Uni match

Find your perfect match

Our tool will help you find the perfect uni course for you

Make your revision easier

Study Help rules and posting guidelines

Groups associated with this forum:

View associated groups

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.