The affect of changing Light intensity on Resistance due to LDR

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Discussion Overview

The discussion revolves around an experiment investigating how the resistance of a circuit changes with varying layers of tracing paper placed over a light-dependent resistor (LDR). The focus includes the relationship between light intensity and resistance, measurement techniques, and experimental design.

Discussion Character

  • Exploratory
  • Technical explanation
  • Homework-related

Main Points Raised

  • Mark B inquires whether the graph of tracing paper layers versus resistance will be linear or curved.
  • Mark B seeks advice on measuring the thickness of tracing paper and asks for suitable apparatus.
  • Mark B also asks how to experimentally demonstrate that gamma rays spread out in different directions.
  • One participant suggests using an LDR, an ohm meter, and tracing paper in a well-lit room to conduct the experiment.
  • Another participant proposes measuring the thickness of a stack of tracing paper and dividing by the number of sheets, acknowledging that this method may not be entirely accurate.
  • Mark B questions whether specific instruments, such as vernier calipers, could be used for measuring thickness.

Areas of Agreement / Disagreement

Participants express various approaches to the questions raised, but there is no consensus on the expected shape of the graph or the best method for measuring thickness. The discussion remains unresolved regarding the experimental demonstration of gamma rays.

Contextual Notes

Participants mention potential inaccuracies in measuring thickness and the need for clarification on experimental methods, but no specific assumptions or definitions are resolved.

PhysicsLearne
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I've got an experiment coming up where I have to find out how the resistance in a circuit changes as more layers of 'tracing paper' are added onto a LDR i.e. as more paper is added the light intensity will fall and as a result the resistance through the circuit will increase.

I am testing for up to 6 tracing papers.

A few questions if any of you could help:

On a graph of tracing paper(s) on the x axis, against resistance on the y axis, can I expect to see a straight line or more a curved graph?

How could you measure the thickness of a tracing paper (which apparatus?)

How could you test (by an experiment) that gamma rays spread out in different directions?

Thanks a lot

Mark B
 
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PhysicsLearne said:
I've got an experiment coming up where I have to find out how the resistance in a circuit changes as more layers of 'tracing paper' are added onto a LDR i.e. as more paper is added the light intensity will fall and as a result the resistance through the circuit will increase.

I am testing for up to 6 tracing papers.

A few questions if any of you could help:

On a graph of tracing paper(s) on the x axis, against resistance on the y axis, can I expect to see a straight line or more a curved graph?

How could you measure the thickness of a tracing paper (which apparatus?)

Mark B

Simple. LDR, Ohm meter, tracing paper, Room with lights on ceiling. try it!

Experiment is what science is all about.
 
bjacoby said:
Simple. LDR, Ohm meter, tracing paper, Room with lights on ceiling. try it!

Experiment is what science is all about.

Hi there,

Thanks a lot for your response. Is your answer in response to the question about how to prove gamma rays spread out in different directions?

Could you help with the other questions if possible too?

Many thanks

M B
 
One way to measure the thickness of the tracing paper would be to get a big clump of it together (say like 100 sheets), measure the thickness of all of that and divide it by how many you have (in this case, 100).

It wouldn't be 100% accurate, but that's the only way I can think of doing it.
 
Epic Sandwich said:
One way to measure the thickness of the tracing paper would be to get a big clump of it together (say like 100 sheets), measure the thickness of all of that and divide it by how many you have (in this case, 100).

It wouldn't be 100% accurate, but that's the only way I can think of doing it.

Hi there,

Is there any specific instrument though? Vernier callipers (sp?) I was told possibly?

Cheers
 

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