Page 178 - Science Class 08

Ex
Exerciseerciseerciseerciseerciseercise
Ex
Exercise
Ex
Ex
Ex
A. Tick (3) the correct op on.
1. The eye-disorder corrected by using convex lenses is:
(a) as gma sm (b) myopia
(c) hypermetropia (d) all of these
2. The eye-disorder corrected by using concave lenses is:
(a) as gma sm (b) myopia

(c) hypermetropia (d) none of these
3. The nerve that carries visual electric signals to the brain is:
(a) re na (b) pupil
(c) op c nerve (d) all of these

4. The distance between the op cal centre and the focus is called:
(a) focal length (b) converging length
(c) incident ray (d) imerging ray

5. If the object is beyond double the focal length of the lens, the image will be:
(a) real, inverted and smaller in size
(b) large, inverted and imaginary in size
(c) imaginary, not inverted and large in size

(d) none of these.
B. Write the correct term for.
1. the lenses that cause the light-rays to converge : _______________________

2. the lenses that cause the light-rays to diverge : _______________________
3. the lenses that are thicker in the middle : _______________________
4. the lenses that are thicker at the ends : _______________________

5. the inner central point of a lens : _______________________
6. the images that can be obtained on screens : _______________________

7. the images that cannot be obtained on screens : _______________________
8. the distance between the focus and the op cal centre : _______________________
9. op cal device used to view very small things : _______________________

10. op cal device used to view very distant things : _______________________
11. op cal device used to take photographs : _______________________
12. eye-disorder due to which distant vision is blurred : _______________________

13. eye-disorder due to which near vision is blurred : _______________________
14. eye-disorder due to which both distant at near visions
are blurred : _______________________

15. the scien st who invented the op cal microscope : _______________________

178 Science-8