Resolving Power of Grating

Pick an option to see whether it holds. If one of them stops you, the theory page is two steps back.

1. 01

   What does "resolving power" of a diffraction grating mean?

   • a) Its ability to separate two closely spaced wavelengths in a spectrum
   • b) Its ability to bend light through large angles
   • c) The total number of lines ruled on the grating
   • d) The brightness of the diffracted spectrum
2. 02

   The resolving power of a grating is given by:

   • a) R = λ/dλ = N/n
   • b) R = λ/dλ = nN
   • c) R = λ·dλ = nN
   • d) R = dλ/λ = nN
3. 03

   Rayleigh's criterion states that two spectral lines are “just resolved” when:

   • a) Their intensities are exactly equal
   • b) The principal maximum of one line falls exactly on the first minimum of the other
   • c) They are separated by more than one full fringe width
   • d) Their diffraction patterns don't overlap at all
4. 04

   If the dip in the resultant intensity curve between two spectral lines disappears completely, the lines are said to be:

   • a) Just resolved
   • b) Well resolved
   • c) Unresolved
   • d) Partially polarized
5. 05

   According to Rayleigh's criterion, increasing the separation between two wavelengths beyond the “just resolved” limit results in:

   • a) The lines merging further
   • b) A deeper dip between the two maxima — clearly resolved lines
   • c) No change in the pattern
   • d) Complete disappearance of both maxima
6. 06

   Resolving power of a grating depends on:

   • a) Only the wavelength of light used
   • b) The order of the spectrum and the total number of lines used
   • c) Only the grating element (grating constant)
   • d) The intensity of the incident light source
7. 07

   If the number of lines N on a grating is doubled while keeping the order n the same, the resolving power:

   • a) Halves
   • b) Remains unchanged
   • c) Doubles
   • d) Becomes zero
8. 08

   Why does resolving power increase in higher-order spectra (e.g. 2nd order vs 1st order)?

   • a) Higher orders have lower intensity, which improves resolution
   • b) R = nN, so a larger n directly increases R for the same grating
   • c) Higher orders use fewer lines, increasing resolution
   • d) Order has no effect on resolving power
9. 09

   How does resolving power differ from dispersive power of a grating?

   • a) They are the same thing, just different names
   • b) Resolving power measures ability to distinguish close wavelengths; dispersive power measures angular separation per unit wavelength
   • c) Dispersive power depends on N; resolving power does not
   • d) Resolving power has units of angle; dispersive power is dimensionless
10. 10

    A grating has 5000 lines illuminated and is used to observe the 2nd order spectrum of sodium light (λ = 589 nm). What is the smallest resolvable wavelength difference (dλ)?

    • a) 0.0295 nm
    • b) 0.059 nm
    • c) 0.118 nm
    • d) 5.89 nm