What is the need of resistor in first IOT project in light sensor

1

I didn’t understand the need for a resistor in 1st IOT light sensor project

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2

The LDR changes its resistance according to the incident light intensity. To measure this change we connect it in a voltage divider circuit. The other resistance has to be fixed and hence a resistor R1 is required. When connected as 3.3v-LDR-A0-R1-Gnd, by voltage division rule, the volatge at A0= 3.3* (R1)/(R1+Rldr).
The voltage can be measured to detect the change in resistance of LDR which is an indirect measurement of light intensity.

3

Hi @aayushsureka2,

Please clarify,
Why do you feel that the resistor is un-necessary in the IoT Light sensor project?

4

A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses.WE ARE ABLE TO MEASURE THE A0 VALUE ONLY BECAUES OF THE RSISTANCE

5

resistors are mainly used when there is a need to sense the absence and presence of the light in this project.

6

If a very high current flows through the LED, it can be damaged. In order to protect the LED from very high current, a resistance is applied in series with the LED. The resistance restricts/controls the flow of current through the LED.

8

What is the value of rldr?