Obtain the formula for combined focal length of two thin lenses in contact.

What do you understand by resolving power of a microscope? How will resolving power of microscope be affected when Wavelength of light used decreases

What do you understand by resolving power of a microscope? How will resolving power of microscope be affected when-

$\left(\mathrm{ii}\right)$ Diameter of objective lens decreases

Draw the graph between angle of incidence $\left(\mathrm{i}\right)$ and angle of deviation $\left(\mathrm{\delta }\right)$ for a triangular prism and show the angle of minimum deviation in it. Prove that in the condition of minimum deviation, the refractive index $\left(\mathrm{n}\right)$ of the material of triangular prism is given by following formula-

$\mathrm{n}=\frac{\sin \left({\displaystyle \frac{\mathrm{A}+{\mathrm{\delta }}_{\mathrm{m}}}{2}}\right)}{\sin \left({\displaystyle \frac{\mathrm{A}}{2}}\right)}$

Where $\mathrm{A}$ is prism angle and ${\mathrm{\delta }}_{\mathrm{m}}$ is the angle of minimum deviation.