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Homework Help: Potential divider

  1. Dec 18, 2014 #1
    1. The problem statement, all variables and given/known data

    http://puu.sh/dzujr/dcf208c4a5.png [Broken]
    2. Relevant equations
    Potential divider concept--> R(R+r)*E=V

    3. The attempt at a solution
    When there is low light, resistence of LDR increase to produce light.

    So, voltage across LDr increases and voltage across thermistor decrease-->lower temperature

    so I think answer B , but it is wrong
    Last edited by a moderator: May 7, 2017
  2. jcsd
  3. Dec 18, 2014 #2


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    Gold Member

    This isn't really "advanced" physics (so the moderators might move it to another sub forum) but..

    That first part is correct. More light (high illumination) causes the resistance of the LDR to fall. That will tend to "pull" the output voltage higher. That reduces your choices to B or D.

    Now what about the thermistor?
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