# 6.1 Electromagnetic energy  (Page 7/27)

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$E=nh\nu ,\phantom{\rule{0.2em}{0ex}}n=1,\phantom{\rule{0.2em}{0ex}}2,\phantom{\rule{0.2em}{0ex}}3,\phantom{\rule{0.2em}{0ex}}. . .$

The quantity h is a constant now known as Planck's constant, in his honor. Although Planck was pleased he had resolved the blackbody radiation paradox, he was disturbed that to do so, he needed to assume the vibrating atoms required quantized energies, which he was unable to explain. The value of Planck's constant is very small, 6.626 $×$ 10 −34 joule seconds (J s), which helps explain why energy quantization had not been observed previously in macroscopic phenomena.

## The photoelectric effect

The next paradox in the classical theory to be resolved concerned the photoelectric effect ( [link] ). It had been observed that electrons could be ejected from the clean surface of a metal when light having a frequency greater than some threshold frequency was shone on it. Surprisingly, the kinetic energy of the ejected electrons did not depend on the brightness of the light, but increased with increasing frequency of the light. Since the electrons in the metal had a certain amount of binding energy keeping them there, the incident light needed to have more energy to free the electrons. According to classical wave theory, a wave's energy depends on its intensity (which depends on its amplitude), not its frequency. One part of these observations was that the number of electrons ejected within in a given time period was seen to increase as the brightness increased. In 1905, Albert Einstein was able to resolve the paradox by incorporating Planck's quantization findings into the discredited particle view of light (Einstein actually won his Nobel prize for this work, and not for his theories of relativity for which he is most famous).

Einstein argued that the quantized energies that Planck had postulated in his treatment of blackbody radiation could be applied to the light in the photoelectric effect so that the light striking the metal surface should not be viewed as a wave, but instead as a stream of particles (later called photons ) whose energy depended on their frequency, according to Planck's formula, E = (or, in terms of wavelength using c = νλ , $E=\phantom{\rule{0.2em}{0ex}}\frac{hc}{\lambda }$ ). Electrons were ejected when hit by photons having sufficient energy (a frequency greater than the threshold). The greater the frequency, the greater the kinetic energy imparted to the escaping electrons by the collisions. Einstein also argued that the light intensity did not depend on the amplitude of the incoming wave, but instead corresponded to the number of photons striking the surface within a given time period. This explains why the number of ejected electrons increased with increasing brightness, since the greater the number of incoming photons, the greater the likelihood that they would collide with some of the electrons.

With Einstein's findings, the nature of light took on a new air of mystery. Although many light phenomena could be explained either in terms of waves or particles, certain phenomena, such as the interference patterns obtained when light passed through a double slit, were completely contrary to a particle view of light, while other phenomena, such as the photoelectric effect, were completely contrary to a wave view of light. Somehow, at a deep fundamental level still not fully understood, light is both wavelike and particle-like. This is known as wave-particle duality    .

Names are of homologous series
what's an hydroxyl group?
A hydroxy or hydroxyl group is the entity with the formula OH. It contains oxygen bonded to hydrogen. In organic chemistry, alcohols and carboxylic acids contain hydroxy groups. The anion [OH⁻], called hydroxide, consists of a hydroxyl group.
okwara
what are the steps to follow when writing the condensed formula of elements
What is organic chemistry
what's organic chemistry?
why do electrons have no mass
hello
Samuel
hello there
Oliver
hi and who say electrons has no mass ? it does have but most at time consider negleable
Eyong
hello
Lagazani
Lagazani
yeah i will calculate it
divine
Because it's mass it very very small compare with mass of atom
Yasmeen
it's simple
lola
consider the rxn of butadiene .Butadiene is prepared by the gas phase catalytic dehydrogenation of 1-butene , at 900K and 1 bar. c4H8 (g)_ C4H6 (g) + H2 (g) (a) In order to suppress side reactions , the butane is diluted with steam before it passes into the reactor.Estimate the conversion
Rodrick
Estimate the conversion of 1-butene for a feed consisting of 10 moles of steam per mole of 1-butene. (b) find the conversion if the inerts were absent and side reactions are ignored .
Rodrick
help me please I have tried
Rodrick
wat is the difference between electrochemical chemical corrosion
Uzor
please how can i solve this project work..modern aid science process and product
Lagazani
what is the definition of chemistry
Sophia pls check on fb u will see transcendence Internationale is a group from here just join over, and ask any question in science from there we here created it
Eyong
the icon is clear white then writing transcendence Internationale study group
Eyong
U will see it
Eyong
for now chemistry is the study of matter and it properties, why and how element combined to form other substances
Eyong
Chemistry is a group that identifies properties of matter and many more
Alona
Wow and chemistry also is the systematic study of nature
Eyong
chemistry is the study of the structure, properties of matter and the effect of addition or removal of heat from substances.
Bra
calculate the relative molecular Mass of the following 1 ZnCl2 2 NaNo3 3 HNO3 4 CaO
2) 23+14+(16×3)= 3)1+14+(16×3)= 4) 40+16= 1) Zn+71= that's how they do it but for Zn I don't know its mass number
Eyong
Reuben u are welcome to join the group transcendence Internationale on fb we created it for science students is a question and answering platform for all science subjects
Eyong
yeah it's fun
Christian
radioactivity is the spontaneous disintegration of the nucleus of an atom of an element to emmit radiation
Vivian
When dividing a certain and uncertain number, you still use sig figs? Ex: 12.86g divided by 12 M&Ms
hi pls who n knows organic chemistry
mi too needs help
Christian
i don't understand
Ekene
I need help too
Christian
What do you struggle with?
Alanna
organic chemistry as a whole
Christian
joy pls I want us to creat this platform fast were we can communicate as international student out from here. in other fields of life lets creat our network from here. as we all know to share personal or social information here is prohibited. So if any is interested notify me
Eyong
yeah
Christian
+237 is my 673423193 what's number hope u guys understand send urs through that number I will creat it
Eyong
sorry +237 is the whats number and complete it here 672014334 sent it here I will join u in the plat form
Eyong
ok
Judith
but am a Ghanaian
Judith
and what country code do I use
Judith
Daniel am nt on wats
Christian
should we creat a group on face...
Eyong
yeah
Christian
Ok so how will I reach every that's here when I creat it
Eyong
Judith
Judith u don't face.... group?
Eyong
Judith y
Christian
don't have an account
Judith
create one
Christian
and what's the meaning of face
Judith
fb
Christian
don't have an account
Judith
Judith is not allow to Spell completely so is a group we want out of here as international student to creat our own network on different fields of of life so we creat it were every one can be reach and that's on face(1×1) book remove the bracket and u will understand
Eyong
ok joy dont have wats judith dont have fb hmmm so either joy download it or judith creat it so u guys choose
Eyong
but if is for me wats will be easy and cheap with all it features
Eyong
ok
Judith
Judith should create an acc
Christian
so is it wats or fb
Eyong
ok i will
Judith
wats
Judith
no plzzzz
Christian
what should we call the name?
Eyong
Transcendence
Judith
on fb right
Judith
so were is it d smarts
Christian
Christian
so all chooses
Judith
wit Wich are we okk wit
Christian
Ok the I got it we creat the fb but joy why don't u like wats
Eyong
I will tell u wen we start
Christian
I like wats
Judith
plzzzzzzzz 4 mai sake
Christian
just write me on messenger I will get ur name mine remain the same as here am putting on a light red lond sleeves
Eyong
ok
Judith
no p
Christian
joy any problem? if am not here tomorrow just tell any one new from this topic about the plan
Eyong
ok
Judith
but still I can't create it
Judith
Judith u said we should call it transcendence what's the meaning
Eyong
ueah
Christian
Eyong
here in Cameroon is 8:46 pm I know u guys I tired meet u tomorrow here and there
Eyong
Daniel can't find u
Christian
are u Christian joy thAt study in Lagos? am standing beside a white car
Eyong
am princess joy
Christian
u re nt serious it's orange nt red
Christian
my bio is MY HAPPINESS IS TO SEE U SUCCEEDING AND ALWAYS IN A HAPPY MOOD THATS MY BIO ON FB
Eyong
seen
Christian
and u Judith
Christian
don't get you
Judith
we are waiting
Christian
wat is periodicity of element
Abraham
visit eyong Daniel on messenger
Christian
wat is periodicity of element
Abraham
Abraham periodicity is the trend of variation in the property of element in the periodic table with increased in atomic number but is mostly on physical properties
Eyong
Judith were are u Transcendence international is waiting
Christian
am coming
Judith
okkk
Christian
so how do I join
Judith
Tru Daniel
Christian
just text me or send frend request I will join u
Eyong
yeah
Christian
hello
Eyong
I also want to join the group of Transcendence
Justice
send message to EYONG DANIEL on messenger
Eyong
he is putting on an orange long sleeve or just read the previous messages u will know how to connect we want everybody from here to join
Eyong
guy am intrested
divine
ok divine type on fb transcendence Internationale u will see many but our icon is white and transcendence Internationale is written in red then study group is in green colour then there is a star also on it
Eyong
what is an atom
An atom is the smallest part of matter that cannot break down further by chemical means
Alanna
hello
Eyong
Long time
Eyong
no talk
Christian
they keep showings me technical errors authentication fail so I could not post
Eyong
okkk
Christian
So what's the latest here
Eyong
nothing ohhh can't find a frnd
Christian
maybe everyone is busy
Eyong
doing wat
Christian
can u pls carry mi along
Christian
an atom is the smallest indivisible particle of an element.
Vivian
atom can be broken down into smaller particle which are the proton electron and neutron
Vivian
what is chemistry
chemistry is a branch of science which deals with the nature composition uses properties and structure of matter
Vivian
Moses n vivan u re welcome to Transcendence international on messenger just search n click invite n I re tere
Christian
what do you mean by transcendence international
Vivian
I want to join the
Justice
it's were we meet one on one to answer questions n share ideas.jos lyk a study group
Christian
Who so ever wanna join type on fb Transcendence Internationale I decorated the icon to be special u will see a star in the centre u will see two hands greeting and a trophy in the end is special is not hiding just look at it on fb u see it
Eyong
then invite any one u know likes science to join not only here but at least all of us here should be there
Eyong
Moses, Vivian ,justice, Judith we are waiting for u guys
Eyong
How can I get to understand better and faster?
Lolz just be patience
omachonu
When water is added to NaOH, the solution becomes hot in the initial stage. Why?
jeffreto
why so you say the the zero after a decimal point is a significant number.... whiles it does not change the value of the numbers involved