Light dependent resistor experiment

Click For Summary
The discussion revolves around a physics coursework experiment using a light-dependent resistor (LDR) to investigate how water depth affects light absorption and resistance. The participant was unable to complete the experiment due to illness and is seeking clarification on the relationship between water depth and light absorption. Initial results indicate that as water depth increases, the rate of light absorption decreases, suggesting a non-linear relationship. Theoretical insights point to an exponential decay law governing light absorption with increasing depth. The participant expresses gratitude for the assistance received in understanding these concepts.
eymen23
Messages
2
Reaction score
0

Homework Statement



Hi there I never managed to get a decent set of results in my physics coursework as I was unfortunately ill for the last few lessons of experiment time! My teacher won't let have an extension and won't let me do any more experimenting during lunch hours!
Basically by using an LDR I was looking at how the depth of water effect the resistance of the LDR (by measuring current) and hence finding out how depth of water affected the amount of light absorbed by the water. I know that obviously that the deeper the water is the the more light will be absorbed meaning the resistance of the LDR will be greater as less light will pass through the water however: I'm unsure as too whether the amount of light absorbed by the water is directly proportional to the depth or not. Could anyone help me...I did manage to get some results which suggested that as the water got deeper the rate at which light was absorbed decreased (as the water got deeper the difference in current between each depth decreased.)


Homework Equations

Ohm's law I=V/R comes into play, I am using a power pack to supply a constant 3 volt voltage to the circuit. So as resistance due to light absorption changes the current will also change.



The Attempt at a Solution



I think I've already outlined my attemt, it's simply I didnt have enough time to complete my experiment as enough different depths to draw an accurate conclusion to how light absorption is affected by depth, so was wondering if anyone on here could help??
 
Physics news on Phys.org
Welcome to PF.

The amount of light should follow an exponential decay law, as depth is increased.
 
Thank you! Very helpful of you, couldn't find any information online anywhere!
 
Last edited:

Thread 'Magnitude of buoyant force in fluids of different densities'

The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?
View full post »

Similar threads

What Experiments Can I Conduct to Investigate Light Sensitive Devices?
  • · Replies 5 ·
Replies
5
Views
1K
What is the operation principle of the LDR?
  • · Replies 14 ·
Replies
14
Views
3K
Why do the headlights on the car become dim when the car is starting?
  • · Replies 4 ·
Replies
4
Views
2K
Is the Photoelectric Effect Proof That Light Is a Particle?
  • · Replies 35 ·
2
Replies
35
Views
4K
Experimenting whether the diameter of a pot affects boiling time for water
  • · Replies 15 ·
Replies
15
Views
3K
Question about light absorbance with liquid solutions
  • · Replies 10 ·
Replies
10
Views
6K
Light bulb & Diode: linear or non-linear elements.
  • · Replies 12 ·
Replies
12
Views
9K
Resistance of wet sponge with voltage
  • · Replies 10 ·
Replies
10
Views
2K
Water wheel model to describe current flow in a circuit
  • · Replies 3 ·
Replies
3
Views
2K
Things to talk about in a Polarization Write-up
  • · Replies 1 ·
Replies
1
Views
2K