photoelectric effect
In photoelectric effect, emission of electrons depend upon intensity of light, and energy of electrons depend upon frequency of incident light.

Electron combines with positive particle to render in neutral.

and one question was about compton shift(scattering of x-rays) was in this paper?

[B]Number[B]

computer 10
Math 9
Analytical 8-9
GK 4-6
English 4-6

Physics,chemistry and foresnsic 21-23

In Sha Allah, hope so more than 60

Emission of Electron depends upon frequency of light.. No matter how much intensity of light you project upon a material, electron will never come out until the frequency of incident light will be greater or equal to threshold frequency.

Question was Electrons combine with ______ to render it Negative charge not Neutral...
options
Positive
Neutral
Negative
None of above

It was not electron volt...Q was potential difference is measured in
so its Volt

There was no Q of Compton shift

Dont remember exact Q of heat transfer...but i think it was collision of particles...and it is conduction

and wave nature of electrons/particles was explained by debroglie first in 1924 then experimented by davisson germer in 1927...so it was debroglie...even he got nobel prize for it in 1929...

Questions were ...
electron volt is a unit of ....which is electric force/energy
other one was wave nature of energy was given by ....de broglie gave theory related electrons and plancks regarding light/photon

English 10
Math 10
Analytical no less than 7-8 (could be 10)
GK 8
Computer 8
subject inshALLAH no less than 25-30

hopefully i have nailed it once again

Question was which one of the following experiment explain the wave nature of Electron..
Ans: Davison- Germer Experiment.


Question was: Electron Volt is unit of?
Ans: Energy.
Other options were Power, Electron Volt,None Of these

Yes, you right........but in other options potential difference was a option......................therefore someone did not agree with me.........and said question was unit of potential difference...............i picked energy

In physics, the electron volt (symbol eV; also written electronvolt) is a unit of energy equal to approximately 1.602×10−19 joule (symbol J). By definition, it is the amount of energy gained by the charge of a single electron moved across an electric potential difference of one volt.

yes. you 100% right......

Clearly written in F.Sc book chapter 19.

Now what is your estimate?

Originally Posted by zunair888 View Post
photoelectric effect
In photoelectric effect, emission of electrons depend upon intensity of light, and energy of electrons depend upon frequency of incident light.

Electron combines with positive particle to render in neutral.

and one question was about compton shift(scattering of x-rays) was in this paper?
I copied this statement from open book of F.Sc physics chapter 19.....is statement in book is wrong?

In the photoelectric effect, light incident on the surface of a metal causes electrons to be ejected. The number of emitted electrons and their kinetic energy can be measured as a function of the intensity and frequency of the light.
the kinetic energy of the electrons is linearly proportional to the frequency of the incident radiation above a threshold value of ν0 (no current is observed below ν0), and the kinetic energy is independent of the intensity of the radiation.
the number of electrons (i.e. the electric current) is proportional to the intensity and independent of the frequency of the incident radiation above the threshold value of ν0 (no current is observed below ν0).

Do you know? what was exact question and their options?
one option was incident light intensity and light frequecy

Bro，check carefully. You are quoting classical theory of light.. according to photo electric effect the emission of electron depend upon frequency of incident photon. Every material has it's own threshold frequency. If incident photon's frequency is less then that frequency electron never come out.

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bro, as i did not study classical theory of light, so i cannot mix both theories..
After searching some data i got.


According to classical wave theory,

Intensity of a wave is the energy incident per unit area per unit time.
Energy carried by an electromagnetic wave is proportional to the square of the amplitude of the wave.


Classical wave theory cannot explain the first 3 observations of photoelectric effect.

1. Existence of the threshold frequency

Since energy of the wave is dependent on the square of its amplitude, the classical wave theory predicts that if sufficiently intense light is used, the electrons would absorb enough energy to escape. There should not be any threshold frequency.


2. Almost immediate emission of photoelectrons

Based on classical wave theory, electrons require a period of time before sufficient energy is absorbed for it to escape from the metal. Accordingly, a dim light after some delay would transfer sufficient energy to the electrons for ejection, whereas a very bright light would eject electrons after a short while. However, this did not happen in photoelectric effect.

Now third heading carefully read, as you read above, these all are observations of photoelectric effect


3. The independence of kinetic energy of photoelectron on intensity and the dependence on frequency

According to classical wave theory, if light of higher intensity is used, the kinetic energy of an ejected electron can be increased. This is because the greater the intensity, the larger the energy of the light wave striking the metal surface, so electrons are ejected with greater kinetic energy. However, it cannot explain why maximum kinetic energy is dependent on the frequency and independent of intensity.


So kinetic energy depends upon frequency

read this link https://www.miniphysics.com/failure-...ve-theory.html

You can read photelectric effect from this link, i am writing each thing with referenece.......... i cannot find last post reference now........ you should also give reference of your post

http://www.physlink.com/Education/AskExperts/ae24.cfm

i think. it will clear your mind.......after reading classical wave theory, anyone can mix,even if i can

@zunair888 and pakengr
chillas guys,there were 99 other mqs in the exam as well.
Pray that you cross the barrier of 65 including photoelectric effect
best of luck

Approximately 1700 candidates applied
So NTS would not take more than 10 days for announcement of result i personally believe.

__________________
If winter comes....can spring be far behind??

I think something is fishy...i called and they said jab mehkama ijazat dega tab v l display...so my guess is again very few would have crossed 65...so they might be sorting out what to do...because its toooo late...results are out even of this sunday.. n this test only had 1600+ candidates....like a piece of cake for nts...so something is fishy....