Measuring output of LDR

In summary, the task is to plan an experiment to determine the effect of different wavelengths of light on the output of an LDR. The plan is to use a lamp with colored filters, and a CdS cell as the standard LDR. The only issue is determining the appropriate ranges for the meters required. One suggestion is to gradually move the LDR closer to the light source and measure the response, while keeping in mind that the filtering will also affect the photon flux. Placing the filter nearer to the LDR may be a better option.
  • #1
Alecdrew
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Homework Statement


it is a reasearch project i have to plan an experiment to find what effect different wavelengths of light, from a lamp which is used to grow plants, will have on the output of an LDR.


Homework Equations





The Attempt at a Solution



so far my plan is (breifly) to use a lamp and put coloured filters in front of it to controll the wavelength. also i have researched a CdS cell which would be the standard lab LDR i will use. The only thing i really need help with is a proximate ranges for meters required. as i have bin looking for days and can't find anything that would help, i am using an ammeter and voltmeter to give the power output. "P=VI"
 
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  • #2
The only thing i really need help with is a proximate ranges for meters required.
The distance between light source and LDR (light dependent resistor) would determine the number of photons arriving at the LDR, by virtue of the area * photon flux.

One could start some distance away from the light source and gradually move the LDR closer and measure the response or signal strength.


This might provide some insight - http://www.doctronics.co.uk/ldr_sensors.htm [Broken]

The filtering will also affect the flux since it will 'filter out' some fraction of the photons. It would perhaps be better to place the filter nearer to the detecting LDR rather than the source.
 
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  • #3



I would first suggest conducting a thorough literature review on the topic to gather background information and see if similar experiments have been done before. This will help you determine the appropriate range for your meters and also provide insight on potential variables that could affect your results.

In terms of your experiment design, it is important to consider controlling for other factors such as the distance between the lamp and the LDR, the intensity of the light, and the angle of the light hitting the LDR. These variables can greatly impact the output of the LDR and should be carefully controlled.

Additionally, you may want to consider using a spectrophotometer to measure the specific wavelengths of light being emitted by the lamp and determine the exact wavelengths you want to test. This will ensure accuracy and precision in your results.

Finally, I would recommend conducting multiple trials for each wavelength and taking the average of the results to reduce the impact of random error. Overall, your proposed experiment is a good starting point, but it is important to carefully consider all variables and plan for potential limitations to ensure reliable and accurate results.
 

What is an LDR?

An LDR, or Light Dependent Resistor, is an electronic component that changes its resistance based on the amount of light it is exposed to.

Why is it important to measure the output of an LDR?

Measuring the output of an LDR allows us to understand its behavior in different lighting conditions, which is crucial for designing and optimizing electronic circuits that use LDRs.

How is the output of an LDR measured?

The output of an LDR can be measured using a multimeter, which measures the resistance of the LDR at different light levels. The results can also be graphed to show the relationship between resistance and light intensity.

What factors can affect the output of an LDR?

The output of an LDR can be affected by factors such as the intensity and type of light source, the distance between the LDR and the light source, and the ambient temperature. The type and quality of the LDR itself can also impact its output.

What are some common applications of LDRs?

LDRs are commonly used in light-sensitive circuits, such as automatic night lights, streetlights, and camera light meters. They can also be used in security systems, solar panels, and other devices that require light sensing capabilities.

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