10.9 The electromagnetic spectrum  (Page 14/32)

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?

A certain 50.0-Hz AC power line radiates an electromagnetic wave having a maximum electric field strength of 13.0 kV/m. (a) What is the wavelength of this very low frequency electromagnetic wave? (b) What is its maximum magnetic field strength?

During normal beating, the heart creates a maximum 4.00-mV potential across 0.300 m of a person’s chest, creating a 1.00-Hz electromagnetic wave. (a) What is the maximum electric field strength created? (b) What is the corresponding maximum magnetic field strength in the electromagnetic wave? (c) What is the wavelength of the electromagnetic wave?

(a) The ideal size (most efficient) for a broadcast antenna with one end on the ground is one-fourth the wavelength ( $\lambda /4$ ) of the electromagnetic radiation being sent out. If a new radio station has such an antenna that is 50.0 m high, what frequency does it broadcast most efficiently? Is this in the AM or FM band? (b) Discuss the analogy of the fundamental resonant mode of an air column closed at one end to the resonance of currents on an antenna that is one-fourth their wavelength.