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Multiple Choice Questions : Reflection and Refraction 1. A ray of light strikes the surface of mirror at an angle of 30 0 with the mirror. The angle of reflection is: (a)  30 0                                 (b) 60 0                  (c) 45 0                  (d) none. 2.  An object 20cm high is placed at a distance of 100 cm from a plane mirror .The size of the image will be. (a)  20 cm        (b)  40cm                     (c)  10cm    ...

Guess Questions Summative Assessment -II(2012-13) SET-01[FM=30] 1. Define 1 kWh.[1] 2. In an oscillating pendulum, at what positions the potential and kinetic energy are maximum ?[1] 3. A piece of stone is tied at one end of a rubber string and holding from other end, it is allowed to immerse partially then fully into water. What difference if any, you will observe, and why ?[2] 4. Differentiate between low and high pitch sound using neat and labeled diagram.[2] 5.An object of 40N weight when immersed in water losses 10N weight. Will the object float or sink why? [2] 6. What does acronym SONAR stand for ? What type of wave does it use?Write any two uses of SONAR. [3] 7. An object is made to fall from different heights 20cm, 40cm and 60cm on a wet sand.(a) What do you observe on the sand ? (b)Explain the reasons of the observations. [3] 8.A sound wave has a frequency of 5000Hz. and wavelength of 20cm. How long will it take to travel 1 km ? [3] 9. What do you mean by work ? ...

Q1) Fill in the blanks:- (a) The World Water Day is on __________. (b) The activated sludge is about __________ water. (c) Water is disinfected by using chemicals like __________ and __________. (d) __________ and __________ are water borne diseases (e)The sewage system were ------ type in olden days. Q2) What is sewage? What does it contain? Q3) Give two examples of organic and inorganic impurities present in sewage. Q4) What is meant by waste water? Q5) How many processes are involved in the treatment of waste water? Name them. Q6) What is the function of the bar screen used in a Wastewater Treatment Plant? Q7) What is sludge? Q8) What is clarified water? Explain. Q9) What is the difference between aerobic and anaerobic bacteria? Q10) Give reasons a. Eucalyptus trees are grown all along sewage ponds. b. Used tea leaves, solid food remains, cotton etc. should be thrown in the dustbin. c. Large amount of waste generated at public places must be disposed off properly. d. Untreated human...

1. An object is placed between two plane mirrors inclined at an angle of 45� to each other. How many images do you expect to see? 2. A convex mirror is held in water. What should be the change in its focal length? 3.If the light from the Sun subtend an angle Q at the pole of a concave mirror of focal length f, where will it converge? Also find the diameter of the image. Draw the necessary ray diagram. 4. When does Snell�s law of refraction fail? 5. How does the frequency of a beam of ultraviolet light changes when it goes from air to glass? 6.State two conditions under which a ray of light suffering refraction from medium 1 to medium 2 does not undergo any change in direction 7.Name the factor on which lateral shift produced by glass slab depends? 8. A glass lens is immersed in water. How is the power of the lens affected? 9. Why is the power of a lens is measured as reciprocal of focal  length? Give reason. 10.A convex lens is made of a material of refractive index m 1 ...

JSUNIL TUTORIAL, BIHAR   IX CH � SOUND QUESTIONS  Q 1 Frequency of a wave motion is 250 Hz. What is its time period? Q 2. What do you mean by an Oscillation of a sound wave? Q 3 Derive a relation between speed, frequency and wavelength of a sound wave? Q 4 A sound wave has a frequency of 2 kHz and wavelength 40 cm. Calculate its speed? Q 5 Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is 440 m/s in a given  medium? Q 6 Calculate a) the wavelength b) the time period of a tuning fork of frequency 512 Hz that is set to vibrate.  Velocity of sound in air is 320 m/s.   Q 7 What is the wavelength of sound waves produced in air by a vibrating tuning fork whose frequency is  256 Hz when the velocity of sound in air is  330 m/s ?   Q 8 Why the flash of lightning due to collision of clouds is seen much before the thunder, although both occur   simultaneously? Q 9 What do you understand by speed of sound? How does it ...

Gist of Lesson for Quick Revision (By JSUNIL) 1. An eye is the most important organ of the human body. It is associated with vision and acts as a vital optical instrument. 2. An eye is spherical in shape of about  2.3 cm diameter  and is covered externally by a hard thick and opaque layer called Sclerotica. The outermost layer of the eye is sclerotic that prtects and holds the eye. 3. Cornea is transparent part bulging  out of eye and allows the light to enter in the eye. Cornea is also known as the window or aperture of the eye. 4. Iris is a  circular  diaphragm having a hole in its centre .this hole is called pupil 5. Iris has muscles and coloured pigments that provide different colour y eyes 6. Iris controls the amount of light entering the eye through the pupil.  7. The pupil becomes small when bright light falls on the eye. However, it becomes wide when there is dim light. Read more key points Visit Links:   Human eyes and Colorful world...

CBSE ADDA: X Chemistry: Periodic Classification of elements 1. Periodic table: The table which classifies all the known elements on the basis of their properties in such a way that elements with similar properties are grouped together. The first classification of elements was as metals and non-metals. This served only limited purpose mainly because of two reasons: (i). All the elements were grouped in to these two classes only. The groupcontaining metals was very big. (ii) Some elements showed properties of both-metals and non-metals and they could not be placed in any of the two classes. 2. All earlier attempts on the classification of the elements were based on their atomic weights. 3. The first attempt towards the classification of elements was made by Johann Dobereiner, a German chemist in 1829. He made sets of three elements which showed similar chemical properties and he called it triads. 4. The Triad was approximately the mean of the atomic weights of the other two members and t...