Physics - Intensity | Olly Britton

Flashcards

What is the intensity of a wave?

The radiant power passing through a surface per unit area.

What is the SIMPLE formula for intensity?

\[I = \frac{P}{A}\]

What is the formula for intensity?

\[I = \frac{P}{4\pi r^2}\]

Why does the intensity of a wave decrease as you move further away?

Energy is conserved but spread over a larger area, so each piece of area gets less energy.

What’s the equation for the intensity of this wave as radiant energy spreads out from a point?

\[I = \frac{P}{4\pi r^2}\]

What’s the formula for the volume of a sphere?

\[\frac{4}{3} \pi r^3\]

What’s the formula for the surface area of a sphere?

\[4\pi r^2\]

What is intensity directly proportional to?

\[\text{intensity} \propto \text{amplitude}^2\]