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Write the condition of n^(th) order maximum in diffraction. |
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Answer» SOLUTION :(i) Angular width of central maximum GIVEN but `2theta=(2lamda)/(d)impliestheta=(lamda)/(d)""....(1)` For first LIGHT, `theta_(1)=(lamda_(1))/(d)` and for second light, `theta_(2)=(lamda_(2))/(d)` `:.(theta_(2))/(theta_(1))=(lamda_(2))/(lamda_(1))""......(2)` But `theta_(2)` is 30% less that of `theta_(1)` That is, `theta_(2)=7-%` of `theta_(1)` `:.(theta_(2))/(theta_(1))=0.7` From equation (2), `(lamda_(2))/(lamda_(1))=0.7` `:.lamda_(2)=0.7xx6000Å=4200Å` That is, wavelength in a liquid is `4200Å`. Wavelength in air `lamda_(1)=6000Å` Wavelength in a liquid `lamda_(2)=4200Å` (ii) Now refractive INDEX of liquid, `n=(lamda_(1))/(lamda_(2))` `=(6000)/(4200)` `:.n=1.43` |
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