Understanding Light Intensity

What is the unit of light intensity?

• Amperes per second

• Joules per second

• Newtons per meter

• Watts per meter squared

Which of the following is true about light intensity?

• It is a vector quantity.

• It decreases with increasing power.

• It is measured in joules.

• It is proportional to the amplitude of a wave squared.

How does light intensity change as it spreads out from a source?

• It remains constant.

• It decreases.

• It increases.

• It fluctuates randomly.

What is the formula for the surface area of a sphere?

• 4πr²

• πr²

• 4πr

• 2πr²

If the intensity of light is 40 W/m² at a distance X, what is the intensity at 2X?

• 40 W/m²

• 20 W/m²

• 10 W/m²

• 5 W/m²

What is the intensity of light at 23.9 meters if it is 100 W/m² at 20 meters?

• 30 W/m²

• 70 W/m²

• 90 W/m²

• 50 W/m²

How is light intensity related to the amplitude of a wave?

• Inversely proportional to the square of the amplitude

• Inversely proportional to the amplitude

• Directly proportional to the square of the amplitude

• Directly proportional to the amplitude

If a wave's amplitude doubles, how does its intensity change?

• It doubles.

• It halves.

• It quadruples.

• It remains the same.

What constant is used in the equation relating intensity and amplitude?

• It varies depending on the situation.

• It is always 10.

• It is always 1.

• It is always 0.

To increase the intensity of light to five times its original amount, by what factor should the amplitude increase?

• Square root of 2

• Square root of 10

• Square root of 3

• Square root of 5