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C) electromagnetic wave

Correct option is (C) Electromagnetic wave

Solution : Yellow and Blue

C) Frequency

Because a flat pane of glass has parallel sides. 

A) Both statements are true

The retina of a human eye has a large number of light sensitive, cells. These cells are of two types,i.e., rod cells and cone cells. The rod-shaped cells show response towards the intensity of light rays, while the cone-shaped cells respond to colors. It is these cone cells, which make it possible for a person to see different colors and distinguish between them.

A) 12.5 N

Explanations:

Fdt = mv-mu from work energy theorem

F = m( v-u)/dt = 5(65-15)/0.2*100 = 5*50/20 = 12.5 N

Red coloured component.

Correct option is  D) 0° to 42°

For scattering of light, particles are required. Since there are no particles in space, the sky appears dark to astronauts.

When a light ray passes obliquely through the atmosphere in an upward direction its path generally changes due to refraction. When the light ray enters the earth’s atmosphere, it undergoes refraction due to the varying optical densities of air at various altitudes. The atmosphere is continuously changing (due to which the optical densities of air at different levels in the atmosphere keep on changing). The air higher up in the sky is rarer but that nearer to the earth’s surface is denser .The continuously changing atmosphere refracts the light. Hence the path generally changes.

True.

Due to the difference in the speed the light of different colors bend at the different angles. In any transparent medium, The red light travels the fastest and the violet light slowest of all the seven colors. Therefore, the red light bends the least, and the violet light bends the most.

Thus dispersion of white light into seven colors occurs because the light of different colors travels at the different speed.

The formation of a rainbow on is due to the dispersion of sun’s light by the raindrops in the atmosphere. But the moon neither has the atmosphere nor the rain drops to create the dispersion and refraction of light hence the astronauts cannot observe the rainbow from the surface of the moon.

Distant: The parallel rays of light coming from distant tree needs a convex eye-lens of low converging power to focus then to form an image on the retina. When looking at the distant tree, ciliary muscles are fully relaxed and the eye lens is very thin. Its focal length is maximum in this position and converging power is minimum to focus the parallel rays on the retina.

Nearby: The diverging rays of light coming from book needs a convex eye-lens of high converging power to focus then to form an image on the retina. When looking at the nearby object, ciliary muscles get stretched and the eye lens becomes thick. Its focal length is minimum in this position and converging power is maximum to focus the diverging rays on the retina.

The dispersion of white light results in splitting up of white light into seven colours also known as a spectrum of white light. This shows that white light is a mixture of seven colours: red, orange, yellow, green, blue, indigo and violet. The dispersion of white light occurs because the angle of refraction of lights of different colours is different when passing through a glass prism, the red colour deviates the least and blue colour deviates the most.

At the time of sunrise or sunset the sun is near the horizon hence the sunlight has to travel the maximum distance to reach us. Due to this large distance, the most of the shorter wavelength blue-colour present in the while light gets scattered out and away from our line of sight, leaving behind mainly red color in direct sunlight beam that reaches our eye. Hence the sky appears red at the time of sunrise and sunset. 

At noon the sun is overhead in the sky. The light coming from the sun has to travel a shorter distance through the atmosphere to reach us. Due to this short journey, only a little blue light gets scattered. Since the light coming is having almost all the components in right proportion hence the sun in the sky overhead appears white to us at noon.

When an object is placed between the pole and focus of concave mirror a magnified, erect and virtual image is obtained.

The speaker in ‘When You are Old’, loved the pilgrim soul of a young lady whom he is addressing in the poem and whose beauty and elegance mesmerized many suitors.

(c) which is questing for true love.

(a) memories.

Correct option is B) Ammonium Hydroxide

(a) her physical beauty.

The motion of any object under the influence of gravity alone is called as free fall.

Diameter of the moon is 3474 km and diameter of Earth is 12742 km. so, Radius of earth is four times the radius of moon.

We can have one ‘new moon’ and one ‘full moon’ during a month which is the time taken by the moon to complete one revolution around the earth. The time period between one full moon and the next full moon is actually the 29.5 days.

Saturn is the second biggest planet of solar system after Jupiter. Saturn is the unique planet of solar system due to presence of well-developed colorful rings around it. The rings of Saturn can be only seen by telescope. Saturn is least dense among all the planets of the solar system. Its density is even less than that of the water.

Pole star remains fixed at the same position in the sky in the north and does not change its position. The pole star appears to be stationary and does not change its position with time because it lies on the axis of rotation of Earth.

The Orion constellation consists of seven or eight bright stars. The Orion constellation is visible in the sky during winter season in the late evenings.

Stars in the sky do not move but they appear as they are moving, due to rotation of earth. Only the pole remains fixed at the same position because it lies above the axis of rotation of earth.

The distances in universe are so large that ‘km’ becomes an extremely small unit to express such large distances. For example the various stars are millions of kilometers away, so ‘kilometer’ unit is not suitable to express the distances between the stars and other celestial objects. So the distances between various celestial bodies are expressed in the unit of ‘light year’. Light year is the distance light can travel in one year. We can calculate the value of ‘one light year’ in ‘kilometers’ by multiplying the speed of light (300000km/s) by the number of seconds in one year (31536000 s). One light year is equal to 9.46×10¹²kms.

Light year is not a unit of time but a unit of distance. If a star is 8 light years away from the earth, it mean that the distance of the star from the earth is so much that light from the star takes 8 years to reach the earth.

The two celestial bodies which we can see easily in the night sky are stars and moon. During daytime due to glare of sunlight, we cannot see any other celestial objects in the sky. But as soon as the sun sets in the evening and it becomes dark, we can see these celestial bodies in the sky.

No, we can’t hear sound on moon as sound needs medium to travel and there is no medium on moon in which sound can travel not even air.

Ursa Major constellation consists of 7 stars arranged in the pattern of big bear. It is also known as ‘big bear’ and ‘great bear’. And Indian name of Ursa Major constellation is ‘saptarishi’.

Light year is the distance light can travel in one year. One light year is equal to 9.4607 × 10¹² km. The statement, ‘a star is 8 light years away from the Earth’ mean that a star is 8 × 9.4607× 10¹² km =75.6856 km away from earth. By saying that a star is 8 light years away from the earth, we mean that the distance of this star from the earth is so much that the light from the star takes eight years to reach the earth.

The distances in universe are so large that ‘km’ becomes an extremely small unit to express such large distances. So the distances between various celestial bodies are expressed in the unit of ‘light year’. Light year is the distance light can travel in one year. One light year is equal to 9.46×10¹²kms.

Those objects which are present in the sky or in the outer space are celestial objects. These objects are also known as heavenly objects. Stars, planets, satellites, asteroids, comets, etc are some example of celestial objects.

Moon has no atmosphere because the moon’s gravity is  \(\frac{1}{6}\)th of Earth’s gravity and that’s not simply strong enough to prevent the atmosphere from escaping. In fact, the moon does have a very thin atmosphere which is very thin to be felt.

A full moon changes into new moon after 15 days. The day on which the whole bright disc of moon is visible to us on earth is called the ‘full moon day’. Thereafter, every night the size of the moon goes on becoming smaller and smaller and after 15 days the moon is not visible again.

Different shapes of the bright, visible part of the moon as seen from the earth during a whole month are called phases of moon. If we observe the moon continuously every night for a month, we’ll find that there is one day in the month when the moon cannot be seen in the night.

• The day on which the moon is not visible at all is called the new moon day.
• On next day, only a small curve like portion of the moon appears in the night sky. This is known as crescent moon.
• Thereafter, every night, the size of the bright, visible part of the moon appears to become bigger and bigger, giving us many shapes including the half moon and more than moon.
• After 15 days, we can see the whole bright disc of the moon in the night sky. So there is also one day in the month when the moon is visible as a perfectly round ball of light in the sky. The day on which the whole bright disc of moon is visible to us on earth is called the ‘full moon day’.
• Thereafter, every night the size of the moon goes on becoming smaller and smaller and after 15 days the moon is not visible again. This moon we again change in full moon after 15 days, and the process is repeated endlessly.

The Ursa Major consists of seven bright stars which are arranged in a pattern resembling somewhat a big bear.

Mass of the Earth is 6×10²⁴ Kgs.

The sun is a star. It is the star around which the earth and other planets revolve. Stars are the celestial objects that are extremely hot and have light of their own. Sun is also a star. Sun is the star which is nearest to the earth. The sun looks much bigger and brighter because it is much nearer to us than any other star.

Alpha Centauri is the closest star to the Earth after the sun. The star is very bright as it is a combination of two stars Alpha Centauri A and Alpha Centauri B. The star is averagely at a distance of 4.3 light years from the Earth.

Jupiter is the largest planet of solar system. Its diameter is 11 times the diameter of earth, and its mass is about 318 times the mass of earth.

Jupiter has 28 moons or satellites. We can see four of its satellite through a telescope.

The agency responsible for development of space science programmes in our country is Indian Space Research Organization (ISRO).

Pole star is like any other star. But the only difference between pole star and any other star is that the pole star lies on the axis of rotation of the Earth so it remains fixed at its position with respect to the position of the Earth whereas other stars appear to be moving with respect to the Earth. The brightest pole star is Polaris lying above the earth’s North Pole.