# Created my first project on bolt

i just created my first project on bolt using the doc attached with it.
the linear graph was successfully made in which there was a LDR and a resistor in the circuit. the line graph collected plots and a graph was plotted between the common terminal in which the LDR and the resistor were placed. but what was the graph about? what did it tell?(like the variation in the value of LDR with light but where was the varying light then?) and how were those plots collected???
please respond to my query anyone…

Hi @Agrimkh54321, the Bolt sends the light intensity values at the data gathering interval that you have specified in the product configuration page.

The LDR collects the raw light intensity value and sends them to the Bolt Cloud.

The resistance of an LDR varies inversely with light fall on it i.e., the resistance of LDR decreases when light fall on it and vice-versa. Bolt module circuit measures the change in resistance and convert it into volt by voltage divider circuit using ohm’s law relation V ∝ R .

First of all congratulations @Agrimkh54321 for completing your first project using Bolt.
Now coming to your first question : What the graph is about? What did it tell? Well, the graph you just ploted gives information about the variation in the intensity of light with time (i.e. its an intensity of light vs time graph). The setup does not measure the intensity of light directly, but instead measures the voltage across the LDR (Light Dependent Resistor). Now you must be thinking how this voltage is related to the intensity of light. Well, the answer is simple : This voltage is directly proportional to the resistance of the LDR, which in turn is inversely proportional to the intensity of light falling on it.
Now coming to your second question : How were these plots collected? Every 5 minutes (or some other interval, depending upon what interval you chose for your product), the bolt module collects the data from your sensor (which in this case is the LDR) and sends it to the Cloud. This transmission takes over through the MQTT messaging protocol. The command “plotChart()” that you used in your code,takes two variables and displays their value in the form of a table. First variable is “time_stamp” : this variable stores time, and the second variable is “light” (or whatever variable name you assigned to pin A0) : this variable stores the data from the LDR sensor.
Hope this answer helps. (Like it if it does. )

As per lecture intensity of light is inversely proportional to the LDR

In term of graph
1.turn on the light waits for at least 10sec and deploy code configuration
Value in graph is increase
2.turn off the light and wait for 10 sec again deploy the code then value is decrease
Hence proved