24.3 The electromagnetic spectrum  (Page 15/33)

Give an example of energy carried by an electromagnetic wave.

In an MRI scan, a higher magnetic field requires higher frequency radio waves to resonate with the nuclear type whose density and location is being imaged. What effect does going to a larger magnetic field have on the most efficient antenna to broadcast those radio waves? Does it favor a smaller or larger antenna?

Laser vision correction often uses an excimer laser that produces 193-nm electromagnetic radiation. This wavelength is extremely strongly absorbed by the cornea and ablates it in a manner that reshapes the cornea to correct vision defects. Explain how the strong absorption helps concentrate the energy in a thin layer and thus give greater accuracy in shaping the cornea. Also explain how this strong absorption limits damage to the lens and retina of the eye.

(a) Two microwave frequencies are authorized for use in microwave ovens: 900 and 2560 MHz. Calculate the wavelength of each. (b) Which frequency would produce smaller hot spots in foods due to interference effects?

(a) Calculate the range of wavelengths for AM radio given its frequency range is 540 to 1600 kHz. (b) Do the same for the FM frequency range of 88.0 to 108 MHz.

A radio station utilizes frequencies between commercial AM and FM. What is the frequency of a 11.12-m-wavelength channel?

Find the frequency range of visible light, given that it encompasses wavelengths from 380 to 760 nm.

Combing your hair leads to excess electrons on the comb. How fast would you have to move the comb up and down to produce red light?

Electromagnetic radiation having a $\text{15}\text{.}0-\mu \text{m}$ wavelength is classified as infrared radiation. What is its frequency?

Approximately what is the smallest detail observable with a microscope that uses ultraviolet light of frequency $1\text{.}\text{20}\times {\text{10}}^{\text{15}}\text{Hz}$ ?

A radar used to detect the presence of aircraft receives a pulse that has reflected off an object $6\times {\text{10}}^{-5}\text{s}$ after it was transmitted. What is the distance from the radar station to the reflecting object?

Some radar systems detect the size and shape of objects such as aircraft and geological terrain. Approximately what is the smallest observable detail utilizing 500-MHz radar?

Determine the amount of time it takes for X-rays of frequency $3\times {\text{10}}^{\text{18}}\text{Hz}$ to travel (a) 1 mm and (b) 1 cm.

If you wish to detect details of the size of atoms (about $1\times {\text{10}}^{-\text{10}}\text{m}$ ) with electromagnetic radiation, it must have a wavelength of about this size. (a) What is its frequency? (b) What type of electromagnetic radiation might this be?

If the Sun suddenly turned off, we would not know it until its light stopped coming. How long would that be, given that the Sun is $1\text{.}\text{50}\times {\text{10}}^{\text{11}}\text{m}$ away?

Distances in space are often quoted in units of light years, the distance light travels in one year. (a) How many meters is a light year? (b) How many meters is it to Andromeda, the nearest large galaxy, given that it is $2\text{.}\text{00}\times {\text{10}}^6$ light years away? (c) The most distant galaxy yet discovered is $\text{12}\text{.}0\times {\text{10}}^9$ light years away. How far is this in meters?