Physics NEET test arrangement, earlier year questions, answers, and solution # 4

PHYSICS NEET TEST ARRANGEMENT:

QUESTION:

Light of frequency 1.5 times the threshold frequency is incident on a photosensitive

material.What will be the photoelectric current, if the frequency is halved and the intensity

is doubled?

               A.       Doubled

              B.        Four times

              C.        One-fourth

              D.        Zero

ANSWER :

                                                                                       ANSWER - D.

SOLUTION:

Reason:

• No photoelectric emanation will happen on the off chance that the frequency of the occurrence light is underneath the threshold frequency.
• The quantity of electrons radiated each second (Photoelectric flow) is relative to the intensity of incident light
• Kinetic energy increments with expansion in frequency over a threshold value. The greatest speed of the photoelectrons relies upon the frequency of the incident light. light.

PHOTOELECTRIC EFFECT:

• The photoelectric effect includes lighting a metal surface with photons of adequately high energy to launch the electrons from the metal.
• The photoelectric effect happens with photons having energies from a couple electron volt to more than 1 MeV.
• The photoelectric effect peculiarities (convert light into electricity) used to change the programmed iris in different sorts of camera and in solar based cells.
• The photoelectric impact assisted physicists with understanding the quantum idea of light.
•  The idea of wave-particle duality was created on account of the photoelectric effect.
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CLARIFICATION OF KINETIC ENERGY:

• Kinetic energy of the discharged electrons is straight corresponding to the frequency of incident radiations over the threshold value

CLARIFICATION OF THE EFFECT OF INTENSITY:

• The quantity of photoelectrons discharged (the photoelectric flow) is corresponding to the intensity. (Independent of the frequency of incident radiation above threshold value).

CLARIFICATION OF THRESHOLD FREQUENCY:

• Under a certain frequency, the photoelectric impact doesn't happen at all. Visible light for alkali metals, near UV for different metals, and extreme UV radiation for non-metals, the threshold frequency or cut off frequency which is utilized to observe the work function.