5. Electrons were ejected from a sodium metal surface by illuminating light of a

Question

5. Electrons were ejected from a sodium metal surface by illuminating light of a specific wavelength on clean sodium metal in a vacuum. The minimum energy required to eject an electron from the surface (photoelectric work function) is 1.82 eV.Determine the wavelength of light photons on the sodium metal when the photoemitted electrons have a maximum kinetic energy of 1.5 ev. (4 pt) A beam of photons passes through a narrow slit. The photons land on a distant screen, forming a diffraction pattern. In order for a particular photon to land at the center of the diffraction pattern, it must pass, - (a) through the center of the slit. (b) through the upper half of the slit. (c) through the lower half of the slit. (d) impossible to decide 6.

Explanation / Answer

5.

We know that by energy balnce,

Enrgy of incoming light= work function + maximum kinetic energy

So,

energy of incoming light will be,

1.82+1.5

3.32eV

also we know that energy will be

hc/

So

hc/=3.32*1.6*10-19

now calculating

3.744*10-7m or

374.4nm

6.

As we know that light always travels in a straight line and it never bends,

So in order to land in the center of the diffraction pattern, it has to pass though the center of the slit only.

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