Question

FIVE-PART PROBLEM: The visible spectrum of colors ranges from approximately 380 nm in wavelength at the violet end to 750 nm at the far red end. You will be making a device to measure the electric fields due to red light in water.

A. What is the frequency associated with the red end of the visible spectrum?

B. When light passes into the water, the speed of light is reduced to ? = ?/?, where ? is the index of refraction. For water, the index of refraction is about 1.33. What is the speed of red light in water?

C. To use an antenna to detect visible light, its length needs to be one-half wavelength. If you wanted to detect the electric field from the red end of the visible spectrum in water, how long would your antenna need to be? (Hint: the wavelength of light changed when the light entered the water. You will have to find the new wavelength.)

D. Suppose your red light is polarized in the vertical direction. How do you need to position your antenna to detect all of it?

E. You place your antenna as you determined in part D. To calibrate your device, you shine light with a known electric field of 10.0000 N/m. Your device detects only a 9.9756 N/m electric field. How many degrees is your device it off from the alignment you planned in part D? (Note: make sure your calculator is in degree mode).

Answer 1