# 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?

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
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
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