Explore topic-wise InterviewSolutions in Current Affairs.

1. The Bear told the Dog that the Lion j is the strongest beast on earth.

2. The Bear was scared of the Lion.

3. The Dog left the Bear as he wanted to have the strongest master on earth and he s had realized that the Lion was the strongest beast on earth.

4. The Dog stayed with the Lion for a long time as the Lion was the strongest beast. It was a good life, and the Dog had nothing to complain of.

1. The Wolf whom the Dog considered to be the strongest, suddenly darted off the path and crept deeper into the forest. This behaviour of the Wiplf surprised the Dog.

2. The presence of the Bear frightened the Wolf.

3. The Dog noticed that the Wolf was scared of the Bear. Hence he approached tlje Bear to make him his master.

4. The Bear wanted to kill a cow and eat it.

Correct option is B. Man

(i) Similarity: The emergent ray is parallel to the incident ray, but it is displaced sideways.

(ii) Difference: For a given angle of incidence, the extent of refraction (bending) is different (in general, less) for a transparent plastic slab relative to the glass slab.

Correct option is B. Wolves

C) remains same

C) remains same

Correct option is  B) 2

The reciprocal of focal length is called power of lens. Power of lens focal

length = 1/ focal length

It is the outermost covering of the eye. It protects the vital internal parts of the eye.

Aim : 

Finding the refractive index of the glass slab. 

Apparatus : 

Glass slab, white chart, pin.

A rainbow is a natural spectrum of sunlight in the form of bows appearing in the sky when the sun shines on raindrops after the rain. The raindrops act like small prisms.

Yes, we can create a rainbow artificially

1. Our atmosphere contains different types of molecules and atoms. 

2. The reason for blue sky is the molecules N₂ and O₂. 

3. The sizes of these molecules are comparable to the wavelength of blue light.

4. These molecules act as scattering centres for scattering of blue light.

• Activity to produce a rainbow in classroom : 
• Take a prism and place it on the table near a vertical white wall. 
• Take a thin wooden plank, make a small hole in it and fix it vertically on the table. 
• Place the prism between the wooden plank and wall. 
• Place a white light source behind the hole of the wooden plank. Switch on the light.
• Adjust the height of the prism such that the light falls on one of the lateral surfaces. 
• Observe the changes in the emerged ray of the prism. 
• Adjust the prism by slightly rotating it till you get an image on the wall. We observe a band of different colours on the wall. 
• These colours are nearly equal to the colours of the rainbow, i.e., VIBGYOR.

1) Rainbow forms and appears when, 

i) tiny water droplets present in the atmosphere (after rain shower), 

ii) sunlight falls on the droplets, 

iii) observer watches the rainbow in a specific direction. 

2) Rainbow forms due to dispersion of sunlight by tiny droplets, present in the atmosphere, which acts as small prisms.

The least distance of distinct vision is 35 cm. This is more than the least distance of distinct vision of an ordinary person. Hence the person is suffering from Hypermetropia. He has to use double convex lens to see his surroundings clearly

Vinay is suffering from Hypermetropia.

f = +50 cm

Power (P) = 100/f D (in cm); P = 100/50 = 2 

D 

Power of the bi-convex lens is 2D.

In this case, the rays coming from the nearby object after refraction at eye lens, forms image beyond the retina.

Maximum focal length is 2.5 cm and minimum focal length is 2.27 cm.

1. The phenomenon involved in his observation is dispersion of light. 

2. Splitting of white light into different colours (VIBGYOR) is called dispersion.

1. Eye lens changes its focal length by the ciliary muscle attached to it. 

2. By relaxing ciliary muslces, the focal length of the eye lens is reached its maximum value. 

3. By straining ciliary muscles, the focal length of the eye lens is reached its minimum value.

In this case the person cannot see the object clearly and comfortably.

a) The boy is suffering from myopia. 

b) Nature of the lens : 

The lens is biconcave lens. It is thin at the middle and thicker at the edges. 

Focal length of the lens :

Given that power is – 2D

P = 100/f (in cm)

(or) f = 100/P = 100/-2 = - 50 cm

Focal length (f) = -50 cm

Hypermetropia or far-sightedness.

Far-sightedness/Long-sightedness/Hypermetropia.

i) 1) The vision defect of person ‘D’ is presbyopia. 

2) Presbyopia happens due to gradual weakening of ciliary muscles and diminishing flexibility of the eye lens. This effect can be seen in aged people. 

ii) Person A’ defect of vision can be corrected by using Biconcave lens. 

iii) Person ’C’ is suffering with similar defect of vision as of ’B’. 

iv) Person ‘E’ has no defect of vision.

The front curved portion of eye, which is covered by a transparent protective membrane is called the cornea.

By touching the spectacles we can find out whether the lens is concave or convex lens and hence the defect from which he suffers.

Myopia (or) short sightedness.

The maximum angle, at which we can see the whole object is called angle of vision

A cataract is an opacity that develops in the crystalline lens of the eye or in its envelope. Early on in the development of age-related cataract the power of the crystalline lens may be increased, causing near-sightedness (myopia), and the gradual yellowing and opacification of the lens may reduce the perception of blue colours. 

Cataracts develop from a variety of reasons, including long-term ultraviolet exposure, exposure to radiation, secondary effects of diseases such as diabetes, hypertension and advanced age; they are usually a result of denaturation of lens proteins.

The statement is true, because a shortsighted person has difficulty in observing far off objects.

A person is said to have developed cataract when the eye lens becomes progressively cloudy resulting in blurred vision. The vision of a person having cataract can be restored after getting surgery done on the eye having cataract. The opaque lens is removed from the eye by surgical operation and a new artificial lens is inserted in its place.

 A person is short-sighted if his eyeball is too long Spectacles with a concave  lens are needed. A person is long-sighted if his eyeball is too short Spectacles with a convex lens are needed. These focus light rays exactly on to the retina

(i) 2.8 cm 

(ii) 2 cm 

(iii) 4 cm 

(iv) 4.5 cm.

Some examples of line segments in daily life

(a) Sides of table 

(b) Piece of pencil 

(c) Piece of chalk 

(d) sides of almirah etc.

On observing we find that following figures are similar 

(i) and (D) 

(ii) and (C) 

(iii) and (A) 

(iv) and (B) 

(v) and (E)

Parallel lines – 

(i) AB and CD, 

(iv) MN and ST 

Intersecting lines – 

(ii) XY and WZ 

(i) PQ and RS

True – (i), (iii), (iv) 

False – (ii), (v)

(ii) protractor

Radius = AO or SO or BO 

Diameter = AB 

Chord = PQ 

Center = O

(iv) Angle which made on bisecting ∠180° is 90°

(iv) Complementary angle of 40° is 140°

Shaded ACB = A circle segment 

Shaded EOD = A sector

1. Humus is obtained from plant and animal wastes. 

2. Micro-organisms act on these wastes and convert them into humus. 

3. Hence, humus is a natural material.

1. Man-made substances are waterproof, lightweight and easy for transportation. Substances in Daily Use 

2. They are easier to use and can be made available in plenty at a low cost. Hence, there is more demand for man-made materials.

Flax fibre is used in the manufacture of currency notes.