# 5.1 The electromagnetic spectrum  (Page 15/33)

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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.

## Problems&Exercises

(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) 33.3 cm (900 MHz) 11.7 cm (2560 MHz)

(b) The microwave oven with the smaller wavelength would produce smaller hot spots in foods, corresponding to the one with the frequency 2560 MHz.

(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?

26.96 MHz

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?

$5.0×{10}^{14}$ Hz

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 $1\text{.}\text{20}×{\text{10}}^{\text{15}}\phantom{\rule{0.25em}{0ex}}\text{Hz}$ ?

$\lambda =\frac{c}{f}=\frac{3\text{.}\text{00}×{\text{10}}^{8}\phantom{\rule{0.25em}{0ex}}\text{m/s}}{1\text{.}\text{20}×{\text{10}}^{\text{15}}\phantom{\rule{0.25em}{0ex}}\text{Hz}}=2\text{.}\text{50}×{\text{10}}^{–7}\phantom{\rule{0.25em}{0ex}}\text{m}$

A radar used to detect the presence of aircraft receives a pulse that has reflected off an object $6×{\text{10}}^{-5}\phantom{\rule{0.25em}{0ex}}\text{s}$ 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?

0.600 m

Determine the amount of time it takes for X-rays of frequency $3×{\text{10}}^{\text{18}}\phantom{\rule{0.25em}{0ex}}\text{Hz}$ to travel (a) 1 mm and (b) 1 cm.

If you wish to detect details of the size of atoms (about $1×{\text{10}}^{-\text{10}}\phantom{\rule{0.25em}{0ex}}\text{m}$ ) 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?

(a) $f=\frac{c}{\lambda }=\frac{3\text{.}\text{00}×{\text{10}}^{8}\phantom{\rule{0.25em}{0ex}}\text{m/s}}{1×{\text{10}}^{-\text{10}}\phantom{\rule{0.25em}{0ex}}\text{m}}=3×{\text{10}}^{\text{18}}\phantom{\rule{0.25em}{0ex}}\text{Hz}$

(b) X-rays

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 $1\text{.}\text{50}×{\text{10}}^{\text{11}}\phantom{\rule{0.25em}{0ex}}\text{m}$ 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 $2\text{.}\text{00}×{\text{10}}^{6}$ light years away? (c) The most distant galaxy yet discovered is $\text{12}\text{.}0×{\text{10}}^{9}$ light years away. How far is this in meters?

Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
what is Nano technology ?
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
hi
Loga
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
how did you get the value of 2000N.What calculations are needed to arrive at it
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