Physics Lab Report. Aim: To find out how a light dependent resistor is affected by light intensity.

Method:

1. Connect up all the wires in order to the resistor and the power supply. Connect the voltmeter to the resistor in series. Attach the light bulb to a socket and put the light bulb facing downwards on the clamp stand.

2. Put the power supply and the light bulb on. Connect the logger pro to the laptop and the light sensor to the logger pro and turn the software on.

3. Put the light sensor and the resistor the same distance away from the bulb.

4. Note down the reading for the light intensity from the logger pro software and also note down the reading of the current and the voltage.

5. Move the light bulb away from both the resistor and the light sensor but such that the light sensor and the resistor are equally apart from the filament light bulb.

6. Again note down the magnitudes of the light intensity, current and voltage.

7. Keep moving the bulb further and further away and keep noting down the new readings until you have a sufficient number.

Data Collection:

Data Processing:

First we calculate the average current and average light intesity

Using V=IR we can calculate resistance since voltage was set at 1.2V at the beginning of the trials. We get the following values:

Plotting a graph of intensity vs resistance:

Now we calculate the logarithmic uncertainty.

Now we plot a graph of log of light intensity against log of resistance with error bars.

Conclusion And Evaluation:

From the results we got the factor that affects the resistance as -0.554 ± 0.345 units. This is a high value of uncertainty 62.27%. This can be attributed to:

1. The light sensor gave a band of values in which the intensity could be. It did not give one specific value.
2. The resistance voltage was given only to one decimal place.

The assumptions in the experiment were:

1. The light in the room did not change in intensity.
2. The light sensor and the resistor were the same distance away from the filament bulb.
3. There was no resistance in the wires.

The improvements that could have been made were:

1. A better light sensor could have been used.
2. We could have made sure that the light sensor was exactly the same distance away from the bulb as the resistance.
3. The room could have been made darker
4. The experiment could have been carried out further away from other students to prevent the light from their experiment interfering with mine.