# Dual Nature Of Matter And Rediations

1. If wavelength of electromagnetic waves are doubled what will happen to energy of photon?

2. Alkali metals are most suitable for photoelectric emission. Why?

3. Out of microwaves, UV, IR which radiation will be most effecting for emission of electrons from a metallic surface?

4. Can X-rays cause photoelectric effect?

5. If the intensity of incident radiation on a metal is doubled what happens to the K.E of electrons emitted?

6. What is the value of stopping potential between the cathode and anode of photocell? If the max K.E of electrons emitted is 5eV?

7. It is easier to remove an electron from sodium than from copper, which has a higher value of threshold wavelength?

8. What is the role of photocell in cinematography?

9. An electron and photon possessing same K.E. Which one will have greater wavelength?

10. In Davisson – Germer experiment if the angle of diffraction is 520 find Glancing angle?

11. What is the energy associated with a photon of wavelength 6000 A0 ?

12. What is the effect on the velocity photo electrons, if the wavelength of incident light is decreased?

13. Show graphically how the stopping potential for a given metal varies with a frequency of the incident radiation.

14. To work functions 2ev and 5ev for two metals x and y respectively. Which metal will emit electrons,when it is irradiated with light and wave length 400nm and why?

15. A photon and an electron have same de-broglie wavelength. Which has greater total energy.Explain?

16. The de-broglie wave length of a photon is same as the wave length of electron. Show that K.E. of a photon is 2mc ג/h times K.E. of electron. Where ‘m’ is mass of electron,c is velocity of light

17. Derive the expression of de-broglie wave length in terms of energy of energy and temperature?

18. Light from bulb falls on a wodden table but no photon electrons are emitted why ?

Following table gives values of work function for a few photosensitive metal.

If each metal is exposed to radiation of wavelength 300nm which of them will not emit photo electron.

20.An electron and alpha particle and proton have same kinetic energy , which have shortest De-broglie wavelength?

21. The De-broglie wave length associated with proton and neutron are equal.Which has greater kinetic energy?.

22.A stream of electron travelling with a speed at right angle to a uniform electric field E, is deflected in a circular path of radius “r” . Prove that e/m = v2/rE.

23.If the potential difference used to accelerate electron is doubled , by what factor the Debroglie wave length of the electron beam changed.

24. The De-broglie wave length associated with an electron accelerated through the potential difference “V” is λ. What will be its wave length , when accelerating potential is increased to 4v?

25.Visible light can not eject photo electrons from copper surface, whose work function is 4.4 ev , why? Prove mathematically.

CBSE Physics (Chapter Wise With Hint / Solution) Class XII (By Mr. Sreekumaran Nair)