Guess Paper – 2013
Class – X
Subject – PHYSICS
(Time One hour and a half)(Full Marks 80)
Answers to this Paper must be written on the paper provided separately.
You will not be allowed to write during the first 15 minutes.
This time is to be spent in reading the Question Paper.
The time given at the head of this Paper is the time allowed for writing the answers.
______
Attempt all the questions from Section I and any four questions from Section II.
The intended marks for questions or parts of questions are given in brackets [ ].
SECTION I (40 Marks)
Attempt all questions from this Section.
Question 1.
(a)A force is applied on (i) a rigid body and (ii) non rigid body. How does the effect of force differ in the two cases. [2]
(b)Define momentum. Give its SI unit. [2]
(c)Why is the mechanical advantage of a lever of the third class always less than one ? Give one example of this class of lever. [2]
(d)Where is the centre of gravity of the following object situated ? 1. A circular disc 2. Equilateral triangle 3. A uniform rod 4. Right circular cone. [2]
(e)Is torque a vector or scalar quantity ? Explain. [2]
Question 2.
(a)Draw a labeled sketch of a class II lever. Give one example of such a lever. [2]
(b)What is meant by (i) Critical angle (ii) Total internal reflection. [2]
(c)Draw a ray diagram to illustrate the action of a convergent lens as reading glasses or magnifying glass. [2]
(d)A glass–slab 2.5 cm thick is placed over a coin. If the refractive index of glass is 3/2, find the height through which coin is raised. [2]
(e)If the speed of light in vacuum is 3 × 108 ms–1 and refractive index of water is 4/3, calculate the speed of light in water. [2]
Question 3.
(a)How does the musical sound differ from noise ? [2]
(b)Does the apparent depth of an object below water depend on the angle of view of the observer in air ? [2]
(c)What are ohmic conductors ? Give one example. Draw a current-voltage graph for such a conductor. [2]
(d)A given wire is stretched to a double its length. How will its resistance change ? [2]
(e)What is the effect of increase in pressure on the melting point of ice and boiling point of water ? [2]
Question 4.
(a)A Radio transmits waves of frequency 107 Hz. Calculate the wavelength of the waves if their speed in air is 3.0 × 108 ms–1. [2]
(b)State two ways of increasing the speed of a dc motor. [2]
(c)What is the mechanism of energy production in a fission reaction ? [2]
(d)Give one difference between a chemical change and a nuclear change.[2]
(e)State the function of the following in a nuclear reactor (i) Moderator (ii) Control rods (ii) Coolant (iv) Concrete wall. [2]
SECTION II (40 Marks)
Attempt any four questions from this Section
Question 5.
(a) A man of mass 60 kg runs up a flight of 30 steps in 15 second. If each step is 20 cm high, calculate the power developed by the man. Take g = 10 ms–2. [3]
(b)Give the advantages of renewable source of energy with example. [3]
(c)What is a pulley ? What is the mechanical advantage of a single fixed pulley ? What is the relation between the mechanical advantage and the number of strands of string used to support the load, in ‘a block and tackle’ set up ? [4]
Question 6.
(a)Draw a ray diagram to illustrate the formation of an enlarged and upright image of an object by a lens. Name the lens used. Where the object should be placed relative to the lens ? Will the image be real or virtual ? Name the device where this action of lens is used. [3]
(b)State two advantages of using a right angled prism as a reflector , rather than a plane mirror. [3]
(c)Why does a rose appear red and leaf green in sunlight ? How would you expect them to appear when viewed in (i) red light, (ii) yellow light, (iii) green light ? Give reasons to your answers. [4]
Question 7.
(a)A vibrating tuning fork is placed over the mouth of a burette filled with water. The tap is opened and the water level gradually falls. I is observed that the sound becomes the loudest for particular length of air column : (i) What is the name of the phenomenon taking place when this happens ? (ii) Why does the sound become the loudest ? (iii) What is the name of the phenomenon taking place when sound is produced for another length of air column and is not the loudest ? [3]
(b)An observer stands at a distance of 850 m from the cliff and fires a gun. After what time gap will he hear the echo, if sound travels at a speed of 350 ms–1 in air ? [3]
(c)Two resistors of resistance 2 ohm and 3 ohm in parallel are connected to a cell of emf 1.5 V and internal resistance 0.3 ohm. Draw a labeled circuit diagram showing the above arrangement and the current drawn from the cell. [4]
Question 8.
(a)Draw a schematic diagram of a circuit consisting of a battery of four 2 volt cells a 5 ohm resistor, an 8 ohm resistor and a 12 ohm resistor and a plug key all connected in series. [3]
(b)A house is fitted with a motor of one horse power, 5 bulbs consuming 0.2 A each and two fans of 80 W each. If all the appliances work for five hours daily, calculate the monthly bill. Energy cost Rs 5.00 per unit. The energy is supplied at 220 V. Given 1 HP = 746 W. [3]
(c)State two ways by which the strength of a magnetic field of an electromagnet can be increased . Why is soft iron generally used as the core of the electromagnet ? State two advantages of an electromagnet over a permanent magnet. [4]
Question 9.
(a)Draw a rough sketch of the pattern of the field lines due to (i) current flowing into a circular coil. And (ii) solenoid carrying current. [3]
(b)Explain why steam pipes warm a building more effectively than hot water pipes in cold countries. [3]
(c)m1 g of steam, at 100˚ C is condensed to form water at 100˚ C. If there is no heat loss to the surroundings, the heat released in this process is used to convert m2 g of ice at 0˚ C into water at 0˚ C. Find : (i) the heat lost by steam in terms of m1. (ii) the heat gained by ice in terms of m2. (iii) Form a heat equation and find the ratio of m2 : m1 from it. (Specific latent heat of vaporization of steam = 2268 kJkg–1 ; Specific latent heat of fusion of ice = 336 kJkg–1 ; Specific heat capacity of water = 4200 Jkg–1˚ C1). [4]
Question 10.
(a) What is main difference between fission reaction and fusion reaction ?Give one example of each. [3]
(b)State the precaution that must be taken while handling a radioactive source. [3]
(c)Why are materials of low work function preferred as thermionic cathode materials ? [2]
(d)A nucleus of an element X which has a symbol 235X92 emits α and then a β radiation. The final nucleus is bYa. Find ‘a’ and ‘b’. [2]
Paper Submitted By:
NameM. P. Keshari
Phone No.09434150289
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