What happens if i wont connect any resistor in the light monitoring project?

Do the project work with out resistor?
What is actually going on process ?what is use of 10 k resistor in Light monitoring project?

if you don’t connect any resistor, then the reading would be zero. The circuit connections is 5V- LDR-A0-Resistor-GND. This is similar to voltage divider circuit. We are able to measure the intensity at A0 only because the resistor is present

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Hi,in the light intensity monitoring system we are using LDR(light dependent resistor) as the name suggests light depends on the resistance value if the light intensity is more then the resistance value decreases and vice versa.So,we are using 10k resistance in the light intensity monitoring system , hence without resistance the reading would be zero and the light intensity doesn’t show any value ,the project doesn’t work without resistance

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Incase you mean to skip the 10k resistor in the circuit, you will end up burning the LED that you use also as it is connected to the Bolt IoT module, there are chances of buring one of the terminals where you have connected the resistor. If in case you mean to skip the Light Dependent Resistor (LDR), then the circuit you made wont work as the LED turns ON turns OFF based on the input that it gets from the LDR.

For any circuit to work properly there should be a connection between ground and vdd .
Here we use resistor to serve the above criteria as well as a voltage divider circuit.

Can someone explain this mathematically

I assume that it’s the 10k ohm resistor that you meant.

We need the 10k ohm resistor because we’re implementing the Voltage-Divider Rule(VDR). Here’s how the voltage divider rule works for our light monitoring project.

The purpose of VDR is to divide the main voltage across the serially connected resistors. Now, understanding that the LDR and the 10k ohm resistors are connected in series, and having the main voltage Vin, the voltages across the LDR and the 10k ohm resistor are given by:

V_ldr = Vin [R_ldr/(R_ldr+10k ohm)]
V_10k = Vin[10k ohm/(R_ldr+10k ohm)]

Thus, in this case, there is dependency of voltage across the LDR(i.e. our required output voltage) on the LDR’s resistance.

Now if we do not use the 10k ohm resistor, the voltage across LDR would be:
V_ldr = Vin
[You may use the same voltage divider rule.]

We see that there is no dependency of the voltage across the LDR on its own resistance, and the sole purpose of using the LDR is not seen. This circuit turns out to be useless.

Hence, it is necessary to use the 10k ohm resistance.

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