1) A movie projector is equipped with a 0.242 m focal length lens that is positioned 0.25 m in front of the film. The distance in front of the lens that a screen must be placed for an image to be in focus is:

2) A radio transmitter broadcasts at a frequency of 103,300 Hz. What is the wavelength of the wave in meters?

3) What is the frequency (in MHz) of an EM wave that has a wavelength of 780 millimeter?

4) What is the wavelength (in nanometers) of the peak of the blackbody radiation curve for something at 2,900 kelvins?