BASIC SCIENCE FOR CLASS 7 AMARNATH MISHRA,PHD GEETA MEHTA ,PHD DEEPTI LEHRI,PHD RAJESH MOHAN, PHD

                       Physic

                        CH- 8

                       Light

A. Answer the following question in not more than 20 words.
Only answers
1. Light travels in straight lines.
2. The incident ray, the reflected ray, and the normal are all coplanar and the angle of incidence is equal to the angle of reflection.
3. The image is virtual, erect, and the same size as the object.
4. The image is real, inverted, and magnified.
5. The image is virtual, erect, and diminished.
6. Between the focus and the pole of the mirror.
7. Between the focus and the optical center of the lens.
8. Torch, headlights, solar cooker.
9. Magnifying glass, microscope, camera.
10. A mixture of all the colors of the rainbow.
B. Answer the following question in not more than 40 words.
Only answer
1. The image formed by a pinhole is inverted because the light rays from the top of the object are bent more than the light rays from the bottom of the object.
2. When parallel rays of light fall on a curved reflecting surface, they are reflected back to a point called the focus.
3. Convex mirrors are used as rear-view mirrors because they give a wider field of view than plane mirrors.
4. The spectrum of white light is the range of colors that make up white light. It can be seen when white light is passed through a prism.
5. A rainbow is formed when sunlight is refracted (bent) and reflected by water droplets in the atmosphere.
6. A Newton's disc appears white when it is rotated because the colors of the spectrum are constantly mixing together.
C. Answer the following question in not more than 60 words.
Only answer
1. Real images are formed when light rays actually intersect after passing through a lens. Virtual images are formed when light rays appear to intersect after passing through a lens. Real images can be projected onto a screen, while virtual images cannot.
2. The focus of a lens is the point where all light rays parallel to the principal axis converge after passing through the lens. To find the focus of a convex lens, hold it in front of a light source and mark the point where the light rays converge.
3. Refraction is the bending of light as it passes from one medium to another. This happens because light travels at different speeds in different media. For example, when light passes from air to water, it bends towards the normal (the line perpendicular to the surface at the point of incidence)
D. Fill in the blanks.
1. An image formed by a plane mirror can be seen on a screen.
2. A real image can be formed on a screen.
3. A convex mirror is one in which the reflecting surface bulges outwards.
4. After parallel rays of light pass through a converging lens, they seem to come from a point called the principal focus.
5. A magnifying glass is a convex lens.

E. Choose the correct option.
Ans=image

Choose the correct option