मराठी
कर्नाटक बोर्ड पी.यू.सी.पीयूसी विज्ञान 2nd PUC Class 12

Quarks inside protons and neutrons are thought to carry fractional charges [(+2/3)e; (–1/3)e]. Why do they not show up in Millikan’s oil-drop experiment?

Advertisements
Advertisements

प्रश्न

Quarks inside protons and neutrons are thought to carry fractional charges [(+2/3)e; (–1/3)e]. Why do they not show up in Millikan’s oil-drop experiment?

टीपा लिहा
Advertisements

उत्तर

Quarks inside protons and neutrons carry fractional charges. This is because nuclear force increases extremely if they are pulled apart. Therefore, fractional charges may exist in nature; observable charges are still the integral multiple of an electrical charge.

shaalaa.com
  या प्रश्नात किंवा उत्तरात काही त्रुटी आहे का?
पाठ 11: Dual Nature of Radiation and Matter - Exercise [पृष्ठ ४११]

APPEARS IN

एनसीईआरटी Physics Part I and II [English] Class 12
पाठ 11 Dual Nature of Radiation and Matter
Exercise | Q 11.37 (a) | पृष्ठ ४११

व्हिडिओ ट्यूटोरियलVIEW ALL [1]

संबंधित प्रश्‍न

Find the (a) maximum frequency and (b) minimum wavelength of X-rays produced by 30 kV electrons.


Why should gases be insulators at ordinary pressures and start conducting at very low pressures?


Would you prefer a material with a high work-function or a low work-function to be used as a cathode in a diode?


Why does thermionic emission not take place in non-conductors?


The cathode of a diode valve is replaced by another cathode of double the surface area. Keeping the voltage and temperature conditions the same, will the place current decrease, increase or remain the same?


Let i0 be the thermionic current from a metal surface when the absolute temperature of the surface is T0. The temperature is slowly increased and the thermionic current is measured as a function of temperature. Which of the following plots may represent the variation in (i/i0) against (T/T0)?


The constant A in the Richardson−Dushman equation for tungsten is 60 × 104 A m−2K−2. The work function of tungsten is 4.5 eV. A tungsten cathode with a surface area 2.0 × 10−5 m2 is heated by a 24 W electric heater. In steady state, the heat radiated by the heater and the cathode equals the energy input by the heater and the temperature becomes constant. Assuming that the cathode radiates like a blackbody, calculate the saturation current due to thermions. Take Stefan's Constant = 6 × 10−8 W m−2 K−1. Assume that the thermions take only a small fraction of the heat supplied.


Define the term "Threshold frequency", in the context of photoelectric emission.  


Emission of electrons by the absorption of heat energy is called ____________ emission.


Why do metals have a large number of free electrons?


Define the work function of a metal. Give its unit.


A 150 W lamp emits light of the mean wavelength of 5500 Å. If the efficiency is 12%, find out the number of photons emitted by the lamp in one second.


In which case is electron emission from a metal not known?


Photoelectric emission is observed from a metallic surface for frequencies ν1 and ν2 of the incident light (ν1 > ν2). If the maximum value of kinetic energy of the photoelectrons emitted in the two cases are in the ration 1 : n then the threshold frequency of the metallic surface is ______.


Consider Figure for photoemission.

How would you reconcile with momentum conservation? Note light (photons) have momentum in a different direction than the emitted electrons.


Give an example each of a metal from which photoelectric emission takes place when irradiated by

  1. UV light
  2. visible light.

The work function of a metal is 2.31 eV. Photoelectric emission occurs when the light of frequency 6.4 × 1014 Hz is incident on the metal surface. Calculate

  1. the energy of the incident radiation,
  2. the maximum kinetic energy of the emitted electron and
  3. the stopping potential of the surface.

Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×