D. Tick ( √ ) the odd-one out giving reason.
1. Mirror, Change in the direction of light, Reflection, Reflected ray, Refraction
Odd one out: Refraction
Reason:
All the other terms — Mirror, Change in the direction of light, Reflection, Reflected ray — are related to the reflection of light. Refraction, on the other hand, refers to the bending of light when it passes from one medium to another, not reflection.
2. Plane mirror, Solar Cooker, Transparent glass sheet, Parabolic mirror
Odd one out: Transparent glass sheet
Reason:
The other three — Plane mirror, Solar cooker, and Parabolic mirror — involve the reflection of light, whereas a transparent glass sheet allows light to pass through without significant reflection.
3. Real image, Convex mirror, Side-view mirror, Vigilance mirror, Virtual image
Odd one out: Real image
Reason:
All the others — Convex mirror, Side-view mirror, Vigilance mirror, Virtual image — are related to convex mirrors, which always form virtual, upright, and diminished images. A real image, on the other hand, is formed by concave mirrors or lenses and can be projected on a screen.
4. Convex lens, Converging lens, Magnifying glass, Real image, Virtual image
Odd one out: Virtual image
Reason:
All the others — Convex lens, Converging lens, Magnifying glass, Real image — are directly associated with convex lenses, which typically form real images (except when used as a magnifying glass). Virtual image is a broader term that can be formed by both concave lenses and mirrors, not specifically by convex lenses.
5. Whitelight, Dispersion, Band of seven colours, Glass slab, Glass prism
Odd one out: Glass slab
Reason:
All the others — White light, Dispersion, Band of seven colours, Glass prism — are directly related to the phenomenon of dispersion of light, where white light splits into seven colours. A glass slab, on the other hand, does not disperse light but simply bends it (refraction) without separating it into different colours.
II. SHORT ANSWER TYPE QUESTIONS
1. You are standing at a distance of 3 m from a plane mirror.
(a) What is the distance of your image from the mirror ?
(b) What is the distance between you and your image ?
Ans. (a) 3 m (b) 6 m
2. Which type of beam is shown in the figure? Light passing through which type of lens produces such beam ?
Ans. Divergent beam of light, Concave lens
3. What is a virtual image ? How is it different from a real image ?
Ans. The image which can be seen only into a mirror but cannot be obtained on a screen is called a virtual image. Whereas the image which can be obtained on a screen is called a real image.
4. Give two points of difference between a convex lens and a concave lens.
Ans. Differences between a convex and a concave lens:
Convex lens | Concave lens |
1. Convex lens is thicker in the middle and thinner at the edges. | 1. Concave lens is thinner in the middle and thicker at the edges. |
2. Convex lens is a converging lens. | 2. Concave lens is a diverging lens. |
5. What is dispersion of light ? What causes dispersion of white light ?
Ans. The splitting of white light into seven colours is called dispersion of white light. Thus, white light (or sunlight) is made up of seven colours. The unequal bending of the lights of different colours causes dispersion of white light (or sunlight).
III. LONG ANSWER TYPE QUESTIONS
1. Write down the English alphabet in which the image formed in a plane mirror appears exactly the same as the alphabet. Give reason.
Ans. A, H, I, M, O, T, U, V, W, X and Y are the English alphabet in which the image formed in a plane mirror appears exactly same as the alphabet. In these alphabet, left and right halves are the same therefore they do not show lateral inversion.
2. What type of mirror is used :
(a) in a searchlight
(b) as a side view mirror in a car
(c) as a shaving mirror
(d) vigilance mirror in a big shop ?
Ans. (a) Concave mirror
(b) Convex mirror
(c) Concave mirror
(d) Convex mirror
3. Mention two uses each of a concave mirror, a convex mirror and a plane mirror.
Ans. Uses of concave mirror :
(i) Concave mirrors are used as reflectors in the headlights of cars, search lights and torch lights etc.
(ii) Concave mirrors are used by dentists to focus light on the tooth to be examined.
Uses of convex mirror :
(i) Rear-view mirrors or side view mirrors in automobiles such as cars, trucks and buses to see the traffic coming from behind.
(ii) Vigilance-mirrors in big shops and store.
Uses of plane mirror :
(i) Plane mirrors are used as a looking glass.
(ii) Plane mirrors are used for making periscope.
4. What do you understand by lateral inversion? Which of the following letters will change on looking in a plane mirror and why ? A, V, M, N, O, P, R .
Ans. When you stand in front of a plane mirror, you find that the right appears left and left appears right in the mirror.
Thus, the image formed in a plane mirror is laterally inverted. The phenomenon is called lateral inversion. The letters N, P and R will change on looking in a plane mirror because, these letters will be laterally inverted.
5. With the help of a diagram show the dispersion of white light by a prism.
Ans.
IV. HIGHER ORDER THINKING SKILLS
1. You are given three mirrors—plane mirror, concave mirror, convex mirror. Identify these without touching them.
Ans. You can identify the mirrors by observing the image they form of your face:
Plane Mirror:
It forms an image that is same size as your face and upright. The image appears to be at the same distance behind the mirror as your face is in front of it.
Concave Mirror:
When you bring your face close, the image appears larger and upright; if you move away, the image becomes inverted and smaller. This mirror shows both magnified and inverted images depending on the distance.
Convex Mirror:
It always forms an image that is smaller, upright, and virtual. The image appears to be deep inside the mirror, giving a wider field of view.
2. Name a mirror that can be used to (a) concentrate rays of light (b) amplify the rays of light.
Ans. (a) Concave mirror (b) Convex mirror
3. What will be the difference in size of the image of the same object formed by a small and large plane mirror ?
Ans. There will be no difference.
No comments:
Post a Comment