Resolving Power of an Astronomical Telescope

The student miscalculated the power of ten when converting centimeters to meters or angstroms to meters, or made an arithmetic error in dividing by $1.22$. Ensure unit conversions to SI units are correct: $D=24.4\text{ cm}=0.244\text{ m}$ and $\lambda =2440\mathring{\text{A}}=2.44\times {10}^{-7}\text{ m}$.

The student omitted the factor of $1.22$ from the Rayleigh criterion formula and used incorrect power-of-ten scaling. Remember that the limit of resolution incorporates the Airy diffraction factor, giving resolving power as $\frac{D}{1.22\lambda }$ rather than $\frac{D}{\lambda }$.

The student calculated the angular limit of resolution $\theta \approx \frac{1.22\lambda }{D}$ instead of resolving power, which is the reciprocal of the limit of resolution. Resolving power is defined as the reciprocal of the angular resolution limit, $\text{RP}=\frac{1}{\mathrm{\Delta }\theta }=\frac{D}{1.22\lambda }$.