What is the term used to describe the intensity of light falling on an area?
Irradiance
How is irradiance defined?
As the power per unit area, measured in watts per square metre (W m-2).
What is the formula to calculate irradiance?
Irradiance (I) = Power (P) / Area (A)
What does the variable ‘P’ represent in the irradiance formula?
Power measured in watts (W).
What does the variable ‘A’ represent in the irradiance formula?
Area measured in square metres (m²).
What law relates irradiance to distance from a light source?
The inverse square law.
What does the inverse square law state about irradiance and distance?
Irradiance is directly proportional to the inverse of the distance squared.
What is the formula representing the relationship between irradiance and distance?
I1/d1² = I2/d2²
What is the purpose of the light meter in the experiment described?
To measure the irradiance at various distances from the light bulb.
What type of graph is produced when plotting irradiance against distance?
A graph that shows the relationship as a curve.
What type of graph is produced when plotting irradiance against the inverse of the distance squared?
A straight line through the origin.
What does a straight line through the origin in the graph indicate?
It proves that irradiance is directly proportional to the inverse of the distance squared.
In the context of the experiment, what does ‘d’ represent?
Distance measured in metres (m).
What is the significance of the experiment described in the notes?
It demonstrates the relationship between irradiance and distance using the inverse square law.
What is the unit of measurement for irradiance?
Watts per square metre (W m-2).
