Use Coupon: CART20 and get 20% off on all online Study Material

Total Price: R

There are no items in this cart.
Continue Shopping
Get instant 20% OFF on Online Material.
coupon code: MOB20 | View Course list

  • Kinematics & Rotational Motion
  • View Details
Get extra R 120 off


The Photon Revealed

7 years ago


Answers : (1)


Curiously enough, although the photon was proposed by Einstein in 1905, a strong case can be made that truly convincing experimental evidence for it emerged only in 1974 and especially in 1986, with the work that we describe in this section. What we seek is an experiment that not only supports the photon concept but that cannot also be explained by the wave concept.

Figure suggests the broad outlines of a possible experiment. Light from source S falls on beam splitter B.A beam splitter is an optical device that splits a beam of light into two sub beams, a transmitted beam (beam X) and a reflected beam (beam Y), each of these sub beams having of photons, a photon approaching a beam splitter has 50% chance of being transmitted and a 50% chance of being reflected.

D1 and D2 in the figure are photoelectric light detectors that respond, respectively, to beams X and Y. the light source S is deliberately made feeble enough so that, on average, the total light energy in the apparatus at any given time is no greater than that of a single photon. Under these conditions each detector output will be a serried of discrete electronic pulses.

If the photon model for light is correct, we expect that if a pulse appears at the output terminal of either detector at a given instant, no pulse will appear at the output terminal of the other detector at that same instant. Such anticoincidence, as they are called, can be detected and recorded electronically by arrangements not shown in the figure.

Early experiments of this kind showed no convincing pattern of anticoincidence and thus no confirmation of the photon model for light. Later it was shown that these negative results could be accounted for by small fluctuations in the intensity of the light source, among other factors. Thus the experiment, as we have described it so far, is not yet a convincing test for the presence or absence of photons.

Note that the apparatus of the figure can not reveal the wave nature of light. Although the incident light beam is split into two sub beams—just as in the double-slit experiment—these beams enter separate detectors and are never recombined. Thus they cannot interfere with each other and cannot possibly produce the interference effects that are the hallmark of the wave model for light.

7 years ago

Post Your Answer

Other Related Questions on General Physics

what is center of mass.............................................???
@ hayathi COM is besically a point at which all of the mass of a body is supposed to be concentrated . if an object is balanced at this point , no net torque act on this object and it will...
Umakant biswal 2 months ago
In physics, the center of mass of a distribution of mass in space is the unique point where the weighted relative position of the distributed mass sums to zero or the point where if a force ...
Shreyas Patil 2 months ago
dear hayathi, It is the imaginary point at which the total mass of the system is supposed to be concentrated.
SAI SARDAR 2 months ago
rgarding calculas and graphs the best book for iit jee with appropriate theory
best book only for graph is "graph & function by s.k. goyal" by JPNP publisher & in my personal view for any difficult function graph, it is the best book ever seen. other best book for...
ADITI SINGH 3 months ago
@ mohammed Kindly mention that u want the books to master only calculus related to maths , for maths problem solving or for physics , which helps in developing physics foundation for...
Umakant biswal 3 months ago
Three books come to my mind All books authored by Amit M Agarwal and Publish by Arihant Play with Graphs Diffrential Calculus. Integral Calculus I have also reviewed Diffrential...
Ajay 3 months ago
A body, having kinetic energy k, moving on a rough horizontal surface, is stopped in a distance x. The force of friction exerted on the body is (1) k x (2) k x (3) k x (4) kx
You no longer have to wait desperately for someone to help resolve your doubt. You can chat with IITians live, 24/7 (even at 3AM!) and get your doubt resolved instantly. Try the HashLearn...
Ankit 3 months ago
From Work Energy Theorem, Wtotal = change in kinetic enrgy -f*x = 0 – k f = k/x is the required friction force.
Vikas TU 3 months ago
what is the velocity in gas?with formula?
where v rms is the root mean square of the speed in meters per second, M m is the molar mass of the gas in kilograms per mole, R is the molar gas constant , and T is the temperature in...
pa1 one year ago
where v rms is the root mean square of the speed in meters per second, M m is the molar mass of the gas in kilograms per mole, R is the molar gas constant , and T is the temperature in...
L GOUSE BASHA one year ago
) as square root of 3RT/m k ( Boltzmann constant energy. This can also be written in terms of the kinetic translational /2 is still the mean RT . This is because despite the larger internal ...
Gavvala Ganesh one year ago
How to derive the expression 1/2 c theta^2,the work done to twist a wire
prateek 8 days ago
Q 17 plz asap plz also tell me how to find out torque direction
@ manas you can calculate the value of torque by the following formula that is = torque = force * perpendicular distance . and the direction of torque are the same as that of the magnetic...
Umakant biswal 4 months ago
torque is herently a vector quantity.part of the torque calculation is the determination of the direction.the direction perpendicular to the radius both of the axis of the axis.
kumar 4 months ago
View all Questions »

  • Complete JEE Main/Advanced Course and Test Series
  • OFFERED PRICE: R 15,000
  • View Details
Get extra R 3,000 off

  • Kinematics & Rotational Motion
  • View Details

Get extra R 120 off

More Questions On General Physics

Ask Experts

Have any Question? Ask Experts

Post Question

Answer ‘n’ Earn
Attractive Gift
To Win!!!
Click Here for details