Light dependent resistor experiment

In summary, the student is seeking help with their physics coursework on how the depth of water affects the resistance of an LDR. They were unable to complete enough experiments due to illness and their teacher not allowing extensions or additional experimenting during lunch hours. The student is unsure if the amount of light absorbed by the water is directly proportional to the depth or not. The student is using Ohm's Law and a power pack to supply a constant 3 volt voltage to the circuit. They are seeking assistance in understanding the relationship between light absorption and depth.
  • #1
eymen23
2
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??
 
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  • #2
Welcome to PF.

The amount of light should follow an exponential decay law, as depth is increased.
 
  • #3
Thank you! Very helpful of you, couldn't find any information online anywhere!
 
Last edited:

What is a light dependent resistor (LDR)?

A light dependent resistor (LDR) is a type of resistor whose resistance changes with the intensity of light falling on it. It is also known as a photoresistor or photocell.

What is the purpose of conducting a light dependent resistor experiment?

The purpose of conducting a light dependent resistor experiment is to observe and measure the changes in resistance of the LDR when exposed to different levels of light. This can help in understanding how LDRs can be used in various electronic circuits as a light sensor or in controlling the brightness of LEDs.

What materials are needed for a light dependent resistor experiment?

The materials needed for a light dependent resistor experiment include an LDR, a power source (such as a battery), a resistor, a multimeter, and a light source (such as a flashlight or a lamp). Optional materials may include a breadboard and jumper wires for easier circuit connections.

How do you set up a light dependent resistor experiment?

To set up a light dependent resistor experiment, first connect the LDR in series with a resistor and a power source. Then, connect the multimeter in parallel to measure the resistance of the LDR. Lastly, place the light source at different distances from the LDR and record the resistance readings on the multimeter.

What are the possible sources of error in a light dependent resistor experiment?

The possible sources of error in a light dependent resistor experiment include ambient light interfering with the readings, improper circuit connections, and variations in the intensity of the light source. It is important to conduct the experiment in a controlled environment and to take multiple readings to minimize error.

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