An astronomical reflecting telescope uses a large parabolic mirror to gather dim light from distant stars. A plane mirror is used to reflect the image to the eyepiece.
1. The length of a telescope is 2 m and the focal length of the objectives is 2.0 cm. What is the focal length of the eyepiece?
a. 194 cm
b. 196 cm
c. 198 cm
d. 200 cm
2. A telescope has an objective lens of focal length 200 cm and an eye piece with focal. length 2 cm. If this telescope is used to see a 50 metre tall building at a distance of 2 km, what is the height of the image of the building formed by the objective lens?
a. 5 cm
b. 10 cm
c. 1 cm
d. 2 cm
3. Image formed by plane mirror is
a. Real and erect
b. Real and inverted
c. Virtual and erect
d. Virtual and inverted
4. What is the focal length of plane mirror?
a. Positive
b. Negative
c. Zero
d. Infinity
5. What is the size of the image formed by plane mirror?
a. Less than the size of object
b. Greater than size of object
c. Same size as object
d. None of these.
