Formatting page ...
Podar International School (ICSE), Pimpri, Pune Prelim 1 Paper (2020-21) Std : X Subject : Physics Marks : 80 Duration : 2 hrs SECTION A (40 Marks) Attempt all questions from this Section. Question 1 i) Explain, why no tracks are left on the ice during ice skating ii) A nut is opened by a wrench of length 10cm. If the least force required is 5.0N, find the moment of force needed to 2 2 turn the nut. iii) What is the work done when the object acted upon by a force remains at rest? 2 iv) v) A single fixed pulley and a movable pulley both are separately used to lift a load of 50 kgf to the same height. Compare the efforts applied. 2 State whether work is done or not by writing yes or no, in the (a) A man pushes a wall. (b) A boy climbs up 20 stairs. 2 Question 2 i) On a see-saw, two children masses 30 kg and 50 kg respectively are sitting on one side of it at distances 2 m and 3 m respectively from its middle. Where should a man of mass 75 kg sit to balance it 2 ii) When a ray of light passes from air to glass, for what angle of incidence, the ray will not be deviated. iii) 2 Where is the object placed in reference to the principal focus of a magnifying glass, so as to see its enlarged image? Where is the image obtained? 2 iv) A postage stamp kept below a rectangular glass block or refractive index 1.5 when viewed from vertically above it, appears to be raised by 7.0 mm. Calculate the thickness of the glass block. 2 v) A ray of light passes from medium 1 to medium 2. Which of the following quantities of the refracted ray will differ from that of incident ray: speed, intensity, frequency, wavelength? 2 Question 3 i) How does the frequency of sound given by a stretched string depend on its (a) length, (b) tension? 2 ii) An object in a denser medium when viewed from a rarer medium appears to be raised. The shift is maximum for which color 2 iii) Which of the following combinations have the same equivalent resistance between X and Y? 2 iv) v) Name the device used to protect the electric circuits from overloading and short circuit. On what effect of current does it work? 2 A substance undergoes (i) a rise in its temperature, (ii) A change in its phase without change in its temperature. In each case, state the energy change in the molecules of the substance. 2 Question 4 i) Calculate the frequency of yellow light of wavelength 550 nm. The speed of light is 3 x 108 ms-1. 2 ii) (a) The earthing of an electric appliance is useful only if the fuse is in the live wire. Given the reason. (b) Name the part of the appliance which is earthed. 2 iii) What happens to the position of an element in the periodic table when it emits? a) alpha particle b) gamma radiations 2 iv) Define the term radioactivity. Of the three normally occurring radioactive radiations: (a) Which has a positive charge? (b) Which is most penetrating? 2 v) Radioactive substances were found to give off three types of rays. Name them. How do they (a) React to the magnetic field? (b) React to the electric field? SECTION B (40 Marks) Attempt any 4 questions from this Section. 2 Question 5 i) Show that the sum of kinetic energy and potential energy (i.e., total mechanical energy) is always conserved in the case of a freely falling body under gravity (with air resistance neglected) from a height h by finding it when (i) the body is at the top, (ii) the body has fallen a distance x, (iii) the body has reached the ground. . 3 ii) Find the result of mixing 10g of ice at -10oC with 10g of water at 10oC. Specific heat capacity of ice is 2.1Jg-1K-1, specific latent heat of ice is 336Jg-1, and specific heat capacity of water 4.2Jg-1 K-1 3 iii) A pulley system has a velocity ratio 3. Draw a diagram showing the point of application and direction of load (L), effort (E) and tension (T). If lifts a load of 150 N by an effort of 60 N. Calculate its mechanical advantage. Is the pulley system ideal? Give reason 4 Question 6 i) Name three properties of ultraviolet radiations which are similar to visible light. 3 ii) Draw a neat labelled ray diagram to locate the image formed by a magnifying glass. State three characteristics of the image. 3 iii) Show with the help of a diagram how a total reflecting prism can be used to turn a ray of light through 90 . Name one instrument in which such a prism is used. Show with the help of a diagram how a total reflecting prism can be used to turn a ray of light through 90 . Name one instrument in which such a prism is used. 4 Question 7 i) A) Draw a sketch showing the displacement of a body executing damped vibrations, against time B) Distinguish between the free (or natural) and forced vibrations 4 ii) iii) An electrical appliance having a resistance of 200 Ohm is operated at 220 V. calculate the energy consumed by the appliance in 5 minutes. (i) in joules (ii) in kWh. 3 A pendulum has a frequency of 5 vibrations per second. An observer starts the pendulum and fires a gun simultaneously. He hears an echo from the cliff after 8 vibrations of the pendulum. If the velocity of sound in air is 340m/s-1. find the distance between the cliff and the observer. 3 Question 8 i) A battery of emf 15 V and internal resistance 3 ohm is connected to two resistors 3 ohm and 6 ohm connected in parallel. Find (a) the current through the battery (b) p.d. between the terminals of the battery (c) the current in 3 ohm resistor (d) the current in 6 ohm resistor. 4 ii) In what unit does the electric meter in a house measure the electrical energy consumed? Derive its value in S.I. unit? iii) 3 (a) What is the purpose of a switch in a circuit? (b) Why is the switch put in the live wire? (c) What precaution do you take while handling a switch? 3 Question 9 i) Find the time taken by a 500 W heater to raise the temperature of 50 kg of material of specific heat capacity 960 J kg-1 K-1, from 18oC to 38oC. Assume that all the heat energy supplied by the heater is given to the material 3 ii) Name three factors on which the heat energy absorbed by a body depends and state how does it depend on them. 3 iii) The temperature of 600 g of cold water rises by 15oC when 300 g of hot water at 50oC added to it. What was the initial temperature of the cold water? 4 Question 10 i) What happens to the postion of an element in aperiodic table when it emits a) Beta particle b) Gamma radiations Give reason for your answer 4 ii) A radioactive source emits three types of radiations. Name them. (a) Name the radiations which are charged. (b) Name the radiations which are most penetrating. (c) Name the radiations which have the largest mass. 3 iii) What are isotopes and isobars? Do isotopes have same chemical and physical properties 3
|
