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PRE-BOARDEXAMINATION2020-21 PHYSICs CLASS-X M.M:80 TIME: 2 HRS SECTION-A (40MARKS) *Attempt all questions **Each question carries 2 Q1. (i) Which has more marks. heat: Ig of ice at 0 C or lg of water at 0C. Give reason. (ii) Write the (ii) Write the latent heat of ice. approximate value ofspecific prineiple of calorimetry and also write the mathematical statement. the electricity. (iv) Write two safety precautions while using (v) Define high tension wires. (vi) What do you mean by Joule's law of heating? in electrical (vii) Why power and voltage is mentioned appliance? (viii) On what factors does the internal resistance of a cell depends. superconductors and also write temperature. (ix) Define two examples with (x) Explain specific resistance and its unit. (xi) Define Ohm's law and its limitations. Write condition for resonance. (xii) Write three conditions to hear echo distinctly. (xiv) Write two uses of ultraviolet radiations. (xv) Which colour of the white light is deviated by the glass (xii) prism. (a) The most (b) the least (1) (xvi) Derive the relationship between kinetic energy and momentum. force and average (xvii) Write two difference between uniform circular motion and uniform linear motion. questions SECTION-B (40MARKS) difference between heat and 4 temperature. (xviii) Express 5kWh into joule. (xix) Derive the relationship between power, two speed. (xx) State *Attempt any to it. What was (3) (3) the Q2.(i) The temperature of 600gm of cold water rises by 15 C when 300gm of hot water at 50 C is added initial temperature of the cold water? (ii) Draw a well-labelled diagram of calorimeter. 4.2J/g/K. cable of three a according (4) (3) (3) to old pin plug and the (1ii) Ikg of water is contained in a 1.25kW kettle. Calculate time taken for the temperature of water to rise from 25 C to its = diagram coding of wire in a well-labelled capacity of water boiling point 100 C. heat Draw Specific 23. (i) socket. Write the colour nd n e w convention. ii) (2) (ii) is 4.0x10J. Express it in eV. (4) used for 3h 2k W. If iron is is rated 220V, An electric iron it cost Rs 4.25 it for o n e week, if Find the cost of running daily. per kWh. electron boiling point. B (b) A and C to be noted about the points 2 2 C (3) series (4) (3) Q4. (1) The energy of an (3) takes kettle connected to a 220V. supply (i) Water in an electric How long will it take if it Sminutes to reach its to 200V. fig. w are resistance between the 2 2 www ww 2 2 network shown in Supply voltage falls (iii) In the D 2 2 A equivalent and B Calculate the (a) A Q5. (1) Write two facts which combination. (3) on 11) A wire of resistance 9ohm having length 30cm is tripled (3) Itself. What is its new resistance? (111) Calculate the equivalent resistance between the point A and (4) B in fig. 2 2 3 2 30 2 ww. AO- 6 ww- OB 4 2 Q6. (i) What length of copper wire of specific resistance 1.7x10 ohm m and radius Imm is required so that its resistance is 1ohm (3) (ii) The power of a motor is 40kW, at what speed can the motor raise a load of 20,000N? (3) (11) A person standing at a distance x in front of a cliff fires a gun. Another person B standing behind the person A and distance y from the cliff hears two sounds of the fired shot after 2s and 3s respectively. Calculate x and y. take speed of sound 320m/s) (4) = (4)
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