photoelectric effect part 1 dual nature of matter physics class 12 by vikas sir jee neet physics

Statement-1 : Photoelectric effect supports the particle nature of light. That means light is not a wave in this case. Statement-2 : The particle nature and the wave nature of light coexist, what we feel is the nature that is dominating at a particular situation.

What is photoelectric effect? State t he result of photoelectric effect experiment that could not be explained on the basis of laws of classical physics. Explain this effect on the b asis of quantum theory of electromagnetic radiations.

In an experiment on photoelectric effect, the slope of the cut off voltage versus frequency of incident light is found to be 4.12xx10^(-15)Vs . Given e=1.6xx10^(-19)C , estimate the value of Planck's constant.

In photoelectric effect the work function of a metal is 3.5 eV. The emitted electrons can be stopped by applying a potential of –1.2 V. Then

Evolution part 1|class 12

In a photoelectric effect experiment, photons of energy 5 eV are incident on the photocathode of work function 3eV . For photon intensity I_(A)=10^(15)m^(-2)s^(-1) , saturation current of 4.0 mu A is obtained. Sketch the variation of photocurrent i_(p) against the anode voltage V_(a) in the figure below for photon intensity I_(A) ( curve A ) and I_(B)=2xx10^(15)m^(-2)s^(-1) (curve B ) ( in JEE graph was to be drawn in the answer sheet itself.)

de Broglie proposed dual nature for electron by putting his famous equation lambda = (h)/(mv). Later on, Heisenberg proposed uncertainty principle as deltapDeltax ge (h)/(4pi). On the contrary, Particle nature of electron was established on the basis of photoelectric effect. When a photon strikes the metal surface it gives up its energy to the electron. Part of this energy (say W) is used by the electrons to escape from the metal and the remaining energy imparts kinetic energy (1//2 mv^(2)) to the ejected photoelectron. The potential applied on the surface to reduce the velocity of photoelectron to zero is known as stopping potential . When a beam of photons of a particular energy was incident on a surface of a particular pure metal having work function =(40 eV), some emitted photoelectrons had stopping potential equal to 22 V. some had 12V and rest had lower values. Calculate the wavelength of incident photons assuming that at least one photoelectron is ejected with maximum possible kinetic energy :

In a class of 55 students the number of students studying subjects are , 23 iin Mathematics 24.in physics 19in chemisty 12 in Mathematics and physics ,9 in Mathematics and chemistry ,7 in physics and chemistry and 4 in all the three subjects. the number of students who have taken ecactly one subject is

It is very commonly thought that the sciences and humanities are producing two cultures which are opposed to each other. Science is even accused of not being sympathetic to the well-being of society. All this is due to the debatable use made by some scientists of their discoveries. However, science has now become increasingly aware of its responsibility towards society. Consequently, many scientists are of the opinion that science should be defined in humanistic terms. According, I.I. Rabi defines science as follows : "Science is an adventure of the whole human race to learn to live in and perhaps to love the universe in which they are. To be a part of it is to understand it, to understand oneself, to begin to feel that there is a capacity within man far beyond that he felt he had, of an infinite extension of human possibilities - not just on the material side..." Rabi proposes that science be taught “with a certain historical understanding, with a certain philosophical understanding, with a social understanding and a human understanding". At the moment, we are dealing with physics and one might well ask if we can define physics also in humanistic terms. Gerald Halton provides us with a relevant definition of physics. According to him : "Physics is a sequence of related ideas whose pursuit provides one with the cumulative effect of an even higher vantage point and a more encompassing view of the working of nature. Physics is neither an isolated bloodless body of facts and theories with mere vocational usefulness, nor a glorious entertainment restricted to an elite of specalists. Rather students of physics may leave them unprepared for their own time. They can be neither participants nor even intelligent spectators in one of the great adventures”. It will be no exaggeration if we say that the fate of society is linked to physics as whatever is thought or discovered in physics immediately affects the society. Our intellegence lies in applying physics to solve the pressing problems that the society faces and not to annihilate it. According to I.I Rabi

The mean and standard deviation of marks obtained by 50 students of a class in there subjects, mathematics, physics and chemistry are given below: Subject Mathematics Physics Chemistry Mean 42 32 40.9 Standard Deviation 12 15 20 Which of the three subjects shows the highest variability in marks and which shows the lowest?