A white dwarf star is approximately the size of Earth but radiates about as much power as the Sun. Estimate the radiation pressure on a light-absorbing object at the white dwarf's surface.

When astronomers observe a supernova explosion in a distant galaxy, they see a sudden, simultaneous rise in visible light and other forms of electromagnetic radiation. How is this evidence that the speed of light is independent of frequency?

A $180 \mathrm{~W} / \mathrm{cm}^2$ laser beam shines on a light-absorbing surface. What's the radiation pressure on the surface?

A laser produces an average power of $7.0 \mathrm{~W}$ in a $1.0 \mathrm{~mm}$ diameter beam. Find $(a)$ the average intensity and $(b)$ the peak electric field of the laser light.

A camera flash delivers $2.5 \mathrm{~kW}$ of light power for $1.0 \mathrm{~ms}$. Find $(a)$ the total energy and $(b)$ the total momentum carried by the flash.

A typical fluorescent lamp is a little more than $1 \mathrm{~m}$ long and a few $\mathrm{cm}$ in diameter. How do you expect the light intensity to vary with distance $(a)$ near the lamp but not near either end and $(b)$ far from the lamp?

Find the peak electric and magnetic fields $1.5 \mathrm{~m}$ from a $60 \mathrm{~W}$ lightbulb that radiates equally in all directions.

At $1.5 \mathrm{~km}$ from a radio transmitter, the peak electric field is $350 \mathrm{mV} / \mathrm{m}$. Assuming the transmitter broadcasts equally in all directions, find $(a)$ the transmitted power and $(b)$ the peak electric field $10 \mathrm{~km}$ from the transmitter.

Lasers are classified according to the eye-damage danger they pose. Class $2$ lasers, including many laser pointers, produce visible light with no greater than $1 \mathrm{~mW}$ total power. They're relatively safe because the eye's blink reflex limits exposure time to $250 \mathrm{~ms}$. Find $(a)$ the intensity of a $1 \mathrm{~mW}$ class $2$ laser with beam diameter $1.0 \mathrm{~mm}$, $(b)$ the total energy delivered before the blink reflex shuts the eye, and $(c)$ the peak electric field in the laser beam.

A quasar $10$ billion light-years from Earth appears the same brightness as a star $50,000$ light-years away. How do the power outputs of quasar and star compare?

The speed of an electromagnetic wave is given by $c=\lambda f$. How does the speed depend on frequency? On wavelength?

High microwave intensities can cause biological damage through heating of tissue; a particular concern is cataract formation. The U.S. Food and Drug Administration limits microwave radiation near the door of a microwave oven to $5.0 \mathrm{~mW} / \mathrm{m}^2$. The window in a particular oven door measures $40 \mathrm{~cm}$ by $17 \mathrm{~cm}$ and is covered with a metal screen to block microwaves. Assuming power leaks uniformly through the window area, what percent of the oven's $900 \mathrm{~W}$ microwave power can leak without exceeding the FDA standards?

Use the fact that sunlight intensity at Earth's orbit is $1368 \mathrm{~W} / \mathrm{m}^2$ to calculate the Sun's total power output.

Show that it's impossible for an electromagnetic wave in vacuum to have a time-varying component of its electric field in the direction of its magnetic field. (Hint: Assume $\vec{E}$ does have such a component, and show that you can't satisfy both Gauss's and Faraday's laws.)