हिंदी
कर्नाटक बोर्ड पी.यू.सी.पीयूसी विज्ञान कक्षा ११

It is Found that Photosynthesis Starts in Certain Plants When Exposed to Sunlight, but It Does Not Start If the Plants Are Exposed Only to Infrared Light. Explain.

Advertisements
Advertisements

प्रश्न

It is found that photosynthesis starts in certain plants when exposed to sunlight, but it does not start if the plants are exposed only to infrared light. Explain.

टिप्पणी लिखिए
Advertisements

उत्तर

Photosynthesis starts when a plant is exposed to visible light. The visible light's photons possess just enough energy to excite the electrons of molecules of the plant without causing damage to its cells. Infrared rays have less frequency than visible light. Due to this, the energy of the photons of infrared rays are not sufficient to initiate photosynthesis. Therefore, photosynthesis does not start if plants are exposed only to infrared light.

shaalaa.com
  क्या इस प्रश्न या उत्तर में कोई त्रुटि है?
अध्याय 42: Photoelectric Effect and Wave-Particle Duality - Short Answers [पृष्ठ ३६३]

APPEARS IN

एचसी वर्मा Concepts of Physics Volume 1 and 2 [English]
अध्याय 42 Photoelectric Effect and Wave-Particle Duality
Short Answers | Q 9 | पृष्ठ ३६३

संबंधित प्रश्न

Define the term 'intensity of radiation' in terms of photon picture of light.


Is it always true that for two sources of equal intensity, the number of photons emitted in a given time are equal?


What is the speed of a photon with respect to another photon if (a) the two photons are going in the same direction and (b) they are going in opposite directions?


In an experiment on photoelectric effect, a photon is incident on an electron from one direction and the photoelectron is emitted almost in the opposite direction. Does this violate the principle of conservation of momentum?


Two photons of 


When stopping potential is applied in an experiment on photoelectric effect, no photoelectric is observed. This means that


Photoelectric effect supports quantum nature of light because
(a) there is a minimum frequency below which no photoelectrons are emitted
(b) the maximum kinetic energy of photoelectrons depends only on the frequency of light and not on its intensity
(c) even when the metal surface is faintly illuminated the photoelectrons leave the surface immediately
(d) electric charge of the photoelectrons is quantised


A photon of energy hv is absorbed by a free electron of a metal with work-function hv − φ.


An atom absorbs a photon of wavelength 500 nm and emits another photon of wavelength 700 nm. Find the net energy absorbed by the atom in the process.

(Use h = 6.63 × 10-34J-s = 4.14 × 10-15 eV-s, c = 3 × 108 m/s and me = 9.1 × 10-31kg)


A beam of white light is incident normally on a plane surface absorbing 70% of the light and reflecting the rest. If the incident beam carries 10 W of power, find the force exerted by it on the surface.

(Use h = 6.63 × 10-34J-s = 4.14 × 10-15 eV-s, c = 3 × 108 m/s and me = 9.1 × 10-31kg)


Answer the following question.
Plot a graph of photocurrent versus anode potential for radiation of frequency ν and intensities I1 and I2 (I1 < I2).


Define the term: stopping potential in the photoelectric effect.


Explain how does (i) photoelectric current and (ii) kinetic energy of the photoelectrons emitted in a photocell vary if the frequency of incident radiation is doubled, but keeping the intensity same?

Show the graphical variation in the above two cases.


In photoelectric effect the photo current ______.


The graph shows the variation of photocurrent for a photosensitive metal

  1. What does X and A on the horizontal axis represent?
  2. Draw this graph for three different values of frequencies of incident radiation ʋ1, ʋ2 and ʋ33 > ʋ2 > ʋ1) for the same intensity.
  3. Draw this graph for three different values of intensities of incident radiation I1, I2 and I3 (I3 > I2 > I1) having the same frequency.

Why it is the frequency and not the intensity of the light source that determines whether the emission of photoelectrons will occur or not? Explain.


If photons of ultraviolet light of energy 12 eV are incident on a metal surface of work function of 4 eV, then the stopping potential (in eV) will be :


A metallic plate exposed to white light emits electrons. For which of the following colours of light, the stopping potential will be maximum?


What is the effect of threshold frequency and stopping potential on increasing the frequency of the incident beam of light? Justify your answer.


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×