Class 10 Physics Half-Yearly Examination (2020) PDF

HALF-YEARLY EXAMINATION (2020) PHYSICS Class 10 Marks : 80 Date : 4. 11.2020 Time : 2 hrs....

HALF-YEARLY EXAMINATION (2020) PHYSICS Class 10 Marks : 80 Date : 4. 11.2020 Time : 2 hrs. SECTION 1 (40 marks) Question 1. (5x2) a) Draw a circuit diagram for verification of Ohm’s law. b) 23592𝑈 emit an alpha and then a beta particle. Find the number of protons and neutrons in the resulting element. c) Knife belongs to which class of lever ? Draw diagram of it. d) State principle of calorimetry. e) Distinguish between terminal p. d and e.m.f of a cell. Question 2. (5x2) a) A boy weighs 75 N on moon. (1) What would be his approximate weight on surface of earth ? (2) What is the reason for your answer ? b) State and define C.G.S unit of work. c) How resistance of a conductor related to mass per unit length and its density ? d) State the energy changes takes place in the following when they are in use : (1) photovoltaic cell (2) electromagnet. e) In what way will the temperature of water at the bottom of water fall be different from the temperature at the top ? Give a reason for your answer. Question 3. (5x2) a) Explain , why electrical gadgets in houses are always connected in parallel ? b) 200 gm of hot water at 800 C is added to 300 gm of cold water at 100 C. Calculate final temperature of the mixture. S.H.C of water is 4200 J.kg-1k-1. c) (1) Define equilibrium. (2) In a beam balance when the beam is balanced in horizontal position , it is in -------------- equilibrium. d) What is the structure of each lens. e) (1) Name one factor which affects the frequency of sound emitted due to vibration in an air column. (2) Name the unit used to measure the sound level. Question 4. (5x2) a) Two resistors 2Ω , 6Ω are connected in parallel and another two resistors 20Ω , 30Ω are connected in parallel. Both these combinations are connected in series , find the net resistance of the circuit. b) Define S.H.C and write a relation between S.H.C and Thermal capacity. c) Draw a graph to show the relation between angle of incidence and angle of deviation. d) Under what condition Class one act like a force multiplier ? Give an example. e) A ball of mass 200 gm falls from a height of 5m. What will be its kinetic energy when it touches the ground ? ( g = 9.8 N/kg.) SECTION II (40 marks) Question 5. (3+3+4) a) Show that energy is always conserved for a freely falling body. b) The weight of a metre ruler is 60gf and two weights 40gf and 75gf are suspended at  25cm mark and 95cm mark. Where the ruler will balance ? c) A block and tackle system has V.R = 5. (1) Draw a labelled for the pulley system. (2) A man exerts a pull of 150 kgf. What is the maximum load he can raise with this pulley system if its efficiency is 80 %. Question 6. (3+ 3+4) a) (1) Define the power of lens. (2) A man claims to have obtained an image twice the size of the object with a concave Lens. Is he correct ? Give a reason for your answer. b) A lens forms an erect and magnified image of an object. (1) Name the lens. (2) Draw a labelled ay diagram to show the formation of image. c) An object is placed at 30 cm infront of a concave lens of focal length 20 cm. Find the distance at which image forms. Also the magnification of image. Question 7. (3+ 3+4) a) A type of electromagnetic wave has wavelength 50 A0. (1) Name the wave. (2) What is the speed of the wave in vacuum ? (3) State one use of this type of wave. b) (1) State one important property of waves used for echo depth sounding. (2) A radar sends a signal to an aircraft at a distance of 30 km away and receives it back after 2 x 10-4sec. What is the speed of the signal ? c) (1) What is meant by the terms (1) pitch (2) timbre ? (2) Explain why stringed instruments , like guitar , are provided with a hollow box ? Question 8. (3+3+4) -1 -1 -1 -1 a) S.H.C of two substances A and B are 3.6 j g K and 0.8 j g K respectively. (1) Which of the two is a good conductor of heat ? (2) How is one confirm to the above conclusion ? (3) If A and B are liquids then which one would be more useful in car radiators ? b) (1) Define Latent heat of fusion of ice. (2) State the relation between thermal capacity and specific heat capacity. c) 250gm of water at 300 C is present in a copper calorimeter of mass 50gm. Calculate the mass of a metal at 750C is dropped in it. The final temperature reached to 5 0C. Given S.H.C of water 4200 J/kg K , copper 390 J/kg K , metal 420 J/kg K. Question 9. (3 +3+4) a) Two resistors 4Ω and 6Ω are connected in parallel to a cell to draw 1.5 amp current from the cell has an internal resistance of 0.6 ohm. (1) Draw a labelled circuit diagram showing the above arrangement. (2) Find the current in 6ohm resistor. (3) P.D across the terminals of the cell. b) Two copper wires are of same length but of different thickness , (1) Which one has more resistance ? (2) Compare their specific resistances. (3) Which wire can be used as heating element ? c) (i) Give two characteristic properties of copper wire which make unsuitable for use as fuse wire. (ii) Name the material which is used as a fuse wire. Question 10. (2+2+3+3) 𝐴 222 a) An element 𝑍𝑆 decays to 85𝑅 after emitting 2α and 1β particle. Find the atomic and mass number of the element S by equation for each emission. b) Draw diagram to show the emission of α ,β ,ϒ rays by a radioactive element. c) Name the radioactive radiations which have , (i) least penetrating power. (ii) maximum ionising power. (iii) no affect of electric and magnetic fields. d) Write precautions to handle radioactive substances.