300+ TOP Photon Interview Questions [UPDATED]

1. What Is Photon ?

It is the quantum of electromagnetic radiation, such as light.

2. What Is Electron ?

Small, negatively charged subatomic particle, every electrically neutral atom has as many orbiting electrons as protons in nucleus.

3. Who Discovered Photoelectric Effect ?

Hall Wachs 

4. Who First Explained The Phenomena Of Photo Electric Effect ?

Albert Einstein

5. Who Discovered Positive Rays ?

Gold Stein

6. What Is An Electron Microscope ?

It is an instrument that uses beam of electrons to produce magnified images of extremely small objects, beyond range of optical microscope .

7. Who Was The First Scientist To Measure The Charge Of An Electron ?

Robert Millikan

8. Ratio Of Charge To Mass Of An Electron Is Called What ?

Specific charge

9. What Helped The Discovery Of Isotopes ?

The study of positive rays.

10. Which Is Known As Cathode Rays ?

The invisible rays coming from the cathode of discharge tube are known as cathode rays.

11. The Specific Charge For Cathode Rays?

Constant

12. What Converts Light Energy Into Electric Energy ?

A photo electric cell.

13. Which Branch Of Physics Can Be Set To Have Begin With The Study Of The Conduction Of The Electricity Through Gasses ?

Atomic physics

14. What Is Based Upon The Conservation Of Energy ?

The photoelectric effect.

15. The Maximum Energy Of The Electrons Released In Photocell Is Independent Of ?

Intensity of incident light.

16. Which Device Is Used To Measure Light Intensity ?

Photocell.

17. What Is The Rest Mass Of Photon ?

Zero

18. Which Are The Different Type Of Photo Electric Cell ?

Photo emissive cell, photovoltaic cell and photo – conductive cell. 

19. What Is A Cathode Ray Oscilloscope ( Cro ) ?

It is an instrument used for plotting one varying physical quantity, potential difference, sound pressure, heart – beat against another current, displacement and time respectively.

20. Who First Attempted To Find The Mass Of An Electron ?

J.J.Thomson in 1897.

21. What Is Called As The Work Function Of A Metal ?

The work function of metal is the amount of energy needed by an electron to cross over the surface barrier of the metal.

22. What Is Vacuum Diode ?

It is an electrostatic device in which the source of electrons is a hot cathode and the manipulation of the current is achieved through the adjustment of potential of the cathode.

23. What Is Space Charge ?

The negatively charged cloud of electrons near the cathode is called space charge. 

24. Who Discovered The Photoelectric Effect ?

Heinrich Hertz in 1887.

25. The Phenomenon Of Emission Of Electrons By Light Is Known As?

Photo electric effect.

26. Who Presented The Quantum Theory Of Radiation ?

Max Planck in 1901.

27. What Is A Photo Emission Cell ?

It consist of a photo cathode and anode mounted in an evacuated glass tube. The cathode is usually a semi – cylindrical plate while anode is a wire ring.

28. What Is A Photo Conductive Cell ?

It is a device whose resistance decreases when illuminated. 

29. Explain Why A Discharge Tube Appears Dark, When Evacuated To Very Low Pressure ?

No discharge passes through the discharge tube as there is no carrier of charge due to very low density at that pressure no collision take place hence no light is emitted. As a result, the discharge tube appears dark.

30. Why Is The Sunlight Not Deflected When Passed Through Either Electric Field Or Magnetic Field ?

The sun light does not contain any charged particles. It is made up of electro magnetic waves hence it is not deflected either by  electric or magnetic field.

31. What Is The Difference Between Thermionic Emission And Photo Electronic Emission ?

The thermionic emission is due to heat, i.e., electrons acquire energy by heat. On the other hand, in photo electric emission, the free electrons in metals observe light photons and acquire energy.

32. Does Each And Every Incident Photon Essentially Effect An Electron ?

No, it may be observed in some other way. Only about 1% of incident photons eject electrons.