Reflecting Telescope

Q. What are the advantages of a reflecting telescope over a refracting telescope?

1. Mirrors can be made bigger than lenses in size.
2. No chromatic aberration.
3. In case parabolic mirror is used, then no spherical aberration.
4. Some light gets blocked inside the refracting telescope, but not reflecting telescope.

Q. An astronomical telescope has a magnifying power $10$. The focal length of the eye piece is $20$ cm. The focal length of the objective is -

1. $2$ cm
2. $200$ cm
3. $\left(\frac{1}{2}\right)\text{cm}$
4. $\left(\frac{1}{200}\right)\text{cm}$

Q. A telescope's objective diameter is 122 cm and light of 800 nm is used. If two stars at distance ${10}^8$ km are observed, what should be the minimum distance between them?

1. 80 km
2. 160 km
3. 40 km
4. 200 km

Q. An astronomical telescope has the objective lens and the eyepiece of focal lengths $80\text{cm}$ and $5\text{cm}$ respectively. Find its magnifying power, if the final image is formed at a distance of $50\text{cm}$ from the eyepiece.

Q. Find the length of the astronomical telescope if it is adjusted such that the final image is formed at the least distance of distinct vision. Focal length of objective lens and eyepiece are $80\text{cm}$ and $5\text{cm}$ respectively.

1. $81\text{cm}$
2. $84\text{cm}$
3. $82\text{cm}$
4. $85\text{cm}$

Q. Calculate the separation of two points on moon that can be resolved using $600\text{cm}$ telescope. Given distance of moon from earth, $=3.8\times {10}^{10}\text{cm}$. The wavelength most sensitive to eye is $5.5\times {10}^{-5}\text{cm}$.

1. $4180\text{cm}$
2. $4100\text{cm}$
3. $4280\text{cm}$
4. $4200\text{cm}$