Atmospheric refraction and scattering

    

CLASS-X

HUMAN EYE AND COLOURFUL WORLD

ASSIGNMENT-2

Q1. Why do we see seven colours due to refraction by a glass prism but, not due to refraction by a glass slab?

Q2. What are the factors affecting refractive index of air?

Q3. Why do we observe the apparent random wavering or flickering of objects when seen through a turbulent stream of hot air rising above fire?

Q4. List the three phenomenon of light responsible for formation of rainbow in the sky.

Q5. Can an observer see a rainbow on the moon? Why? Why not?

Q6. List 3 situations where u can observe tyndall effect.

Q7. On a sunny day, stand at a certain distance from a fountain of water such that the position of the sun is at your back. What do you observe? Explain the reason for your observation.

Q8. Is the position of a star as seen by us its true position? Justify your answer.

Q9. Does a beam of white light give a spectrum on passing through a hollow prism?

Q10. What would have happen if there would have been no atmosphere on the Earth?

Q11. Name any 3 phenomenon based on scattering of light.

Q12. Why are the clouds generally white?

Eye

CLASS-X

THE HUMAN EYE AND THE COLOURFUL WORLD

ASSIGNMENT-1

Q1. Name the outermost part of human eye.

Q2. Write the function of iris in the human eye.

Q3. Name the type of lens used to correct presbyopia.

Q4. When we enter a dim-lit room from a bright light, we are not able to see the object in the room for some time. Explain, why?

Q5. Why do we have two eyes instead of one eye?

Q6. A student has difficulty in reading the black board while sitting in the last row. What could be the defect the child is suffering from? How can it be corrected?

Q7. What happens to the image distance in the eye when we increase the distance of an object from the eye?

Q8. A chicken can see only in the bright light. What type of cells are present in its retina?

Q9. A person is unable to see objects nearer than 50cm. He wants to read a book placed at a distance of 25cm. Find the nature, focal length and power of the lens, he requires for his spectacles.

Ans : f= +50cm , P=2D, convex lens

Q10. The near point of a hypermetropic eye is 1m. What is the power of the lens required to correct this defect? Assume that the near point of the normal eye is 25cm.

Ans:  f= 33.3cm=0.33m

         P=+3.0D (convex lens )

Q11. A person is able to see objects clearly only when these are lying at distance between 50cm and 300cm from his eye.

i)                   What kind of defect of vision he is suffering from?

ii)                 What kind of lens will he require to increase his range of vision?

Q12. A person can see clearly only up to 3m. Prescribe a lens for spectacles so that he can see clearly up to 12m. Defect is myopia.

Ans : A concave lens of focal length 4m should be used.

Stars and Solar System

CLASS-VIII

STARS AND SOLAR SYSTEM

ASSIGNMENT-8

Q1. Fill in the blanks:

a)    A celestial body that revolves around a planet is known as ______________ while that revolving around a star is called a _______________.

b)    Asteroids are found between the orbits of ____________ and _____________.

c)     Alpha centauri is at a distance of ______ light years from the earth.

d)    One A.U. = _____________m.

e)     The temperature on the moon varies from ________ at noon to _______ at night.

f)      A day on mercury equals nearly _____ earth days.

g)    One ‘Jupiter Year’ equals nearly ______ earth years.

h)    The tail of a comet is always directed ________ from the sun.

Q2. Name any 3 artificial Indian satellites.

Q3. Give the other name of meteors.

Q4. Name the astronauts who landed on moon in 1969.

Q5. Name the two bright stars present in Orion constellation.

Q6. List 3 conditions which help in sustaining life on Earth.

Q7. Draw a labelled diagram to show the position of the earth in different seasons.

Q8. What do you understand by the statement that a star is 8 light years away from the Earth?

Q9. Draw sketches to show the relative positions of prominent stars in

a)    Ursa Major

b)    Orion

Q10. Name the inner planets and the outer planets of the solar system.