What is the relationship between light intensity and resistance in a Light Dependent Resistor? Aim: To find out how a light dependent resistor is affected by light intensity. Hypothesis: A light dependent resistor is one that changes its resistance with a change in the light intensity on it. Hence if we can find the light intensity that is on the resistor and its resistance, we can see what factor the resistance is affected by.
Variables: Independent: Light Intensity Dependent: Current Controlled: Voltage, Resistor used, Ambient light, Filament Light Bulb used, light sensor and resistor. Apparatus: 1. Filament Light Bulb 2. Clamp Stand 3. Light Dependent Resistor 4. Voltmeter 5. Wires 6. Light Sensor 7. Logger Pro 8. Laptop 9. Power Supply 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.
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.