Page 179 - Science Class 08

C. Name.
1. two types of images in rela on to screen

____________________ ____________________
2. two types of images in terms of size
____________________ ____________________

3. two types of images in terms of posi on
____________________ ____________________
4. three common eye-disorders :
___________________ __________________ ___________________

D. Match the following columns.
Column I Column II

1. Convex lens a. Two equal arcs back to back
2. Concave lens b. Inner film of the eye
3. Real image c. Coloured part of the eye
4. Iris d. Two equal arcs face to face

5. Re na e. Obtainable on the screen
E. Fill in the blanks.

1. Two other name for a convex lens are ______________ and ______________ .
2. Two other names for a concave lens are ______________ and ______________ .
3. _________________ lenses refract the rays of light inwards.
4. _________________ lenses refract the rays of light outwards.

5. The image is equal in size of the object, if the object is placed at ____________________ .
F. Very short answer ques ons.
1. Refrac ve index can be defined for both transparent and opaque objects. True or False?

2. Light bends as it passes from one medium to another. What is this phenomenon called?
3. A pencil dipped obliquely in water appears bent at the surface due to dispersion. True or
False?
4. In a prism, the emergent ray is parallel to the incident ray. True or false?
5. A transparent medium bends light by the same amount irrespec ve of the colour of light.
True or false?
6. Which of these has a smaller focal length–a thick lens or a thin lens?

7. If an object is situated at the focal point of a convex lens, where is the image formed?
G. Short answer ques ons.
1. What do you mean by lens? How many types of lenses are there?

2. What do you mean by concave lens?
3. How convex lens help in the correc on of hypermetropia?
4. Explain magnifying glass.

Science-8 179