What Determines Voltage Changes in LDR Darkness Sensors?

  • Thread starter Thread starter Eisen
  • Start date Start date
  • Tags Tags
    Circuit Sensor
AI Thread Summary
The discussion focuses on understanding the voltage divider in a circuit involving a Light Dependent Resistor (LDR) and its output voltage. Participants seek clarification on which components form the voltage divider and where the voltage output is located. Additionally, there is confusion regarding the relationship between resistance and voltage in the LDR, specifically why voltage increases with higher resistance and decreases with lower resistance. The need for a clear explanation of these concepts is emphasized, as the referenced webpage lacks sufficient detail. Understanding these principles is crucial for effectively utilizing LDR darkness sensors.
Eisen
Messages
14
Reaction score
0
Here's the circuit-

darkness sensor.JPG


It isn't clear to me which part of this circuit makes the voltage divider and also it doesn't show where the voltage output is on the circuit. Can someone tell me those two things please. Also I don't understand why voltage increases as resistance increases in the LDR and why voltage decreases as resistance decreases in the LDR. Can someone explain that too please. It doesn't give an explanation why on this webpage I'm looking at.
 
Physics news on Phys.org
Anyone?
 

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
View full post »
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

What is the operation principle of the LDR?
Replies
14
Views
2K
LDR circuit electricity question
Replies
3
Views
2K
Current Flow Through Lamps in Circuits
Replies
9
Views
2K
Understanding example in Wikipedia entry for open circuit voltage
Replies
3
Views
2K
How does this potential divider circuit work?
Replies
1
Views
597
Calculation of current in driven series RLC circuit
Replies
8
Views
2K
What does a Zener diode do in a circuit with non-ideal voltage source?
Replies
3
Views
943
Changing capacitance effect on ripple in full rectification circuit
Replies
4
Views
3K
Electricity -- Effect of heating a thermistor in this circuit
Replies
14
Views
2K
Circuits question, series vs parallel
Replies
5
Views
2K

Hot Threads

Recent Insights

Back
Top