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Smt. Sulochanadevi Singhania School, Thane 2nd Prelim Physics Paper Std :10 Max. Marks - 80 Time -2hr Date-04.02.16 SECTION 1 ANSWER ALL THE QUESTIONS: Q1. (I)(a) What happens to the heat supplied to a substance when the heat supplied causes no change in the temperature of the substance? b) Give one example where high specific heat capacity of water is used as a heat reservoir. (1+1) (ii) Define the term specific latent heat of fusion of a substance. (2) (iii)A stretched wire 0.8m long is made to vibrate in two different modes as shown in the figure A and B given below. (2) (A) (B) a) Compare the wavelength of A and B b) In which case is the note produced is louder? Give a reason for your answer. (iv) An ultrasonic wave is sent from a ship towards the bottom of the sea. It is found that the time interval between the sending and receiving of the wave is 1.5s. Calculate the depth of the sea if the velocity of sound in sea water is 1400m/s. (2) (v) In the given figure a ray of light is incident at an angle of 59 at the midpoint of the side PQ of a rectangular slab PQRS. The refractive index of glass is 1.7; the angle of refraction is 30 . Complete the path of the ray (sin 36 =0.5882) (2) P S Q R 59 Q2. (i) If a g =1.5, what is the critical angle for the glass-air interface? (2) (ii) Two waves A and B have wavelength 0.01A and 9000A respectively. (a) Name the two waves. (b) Compare their velocity in air. (2) (iii)Define the absolute refractive index of a medium. (2) (iv)When the string used to uniformly whirl around water balloon in a circular path breaks, the balloon flies off. Which way does it fly and why? (2) (v)A thorium isotope 223 Th90 undergoes an decay and changes into radium. (a) What is the atomic number and mass number of the radium produced? (2) (b)If radium undergoes a further disintegration and emits two -particles, represent this reaction in the form of an equation. (2) Q3 (i) State the energy change that take place in each of the following(a)An electromagnet (2) (b) a photograph is taken. (ii)What happens to the kinetic energy when (a) The mass of the body is doubled at constant velocity (b) The velocity of the body is doubled at constant mass. (2) (iii) A constant force of 100 N displaces a particle (a) 4m in the direction of force (b) 5m at an angle of 60 from the direction of force. Calculate work done by the particle in each case. (2) (iv) Suggest one way in each case by which we can detect the presence of (a) infrared radiations (b) ultraviolet radiations. (2) (v) Draw a ray diagram to show dispersion of white light by a prism. (2) Q4 (i) Two wires of equal lengths, one of copper and the other of manganin, have the same resistance. Which wire will be thicker? Why? (2) (ii) The equivalent resistance of the following circuit diagram is 4 . Calculate the value of x. (2) 5 A X B 8 4 (iii) Explain why the earth pin of 3 pin plug is made thicker and longer than other two. (2) (iv) Explain clouds are generally white in colour. (2) (v) Fill in the blanks to complete the sentences (a) A fuse is a small piece of wire of low --------------- and high---------------------. (b) Energy spent in 1kilo volt ampere hour=-------------------------- J. SECTION 2 ANSWER ANY 4 Q5. (I) (a) with the help of a simple diagram show that mechanical advantage of a single movable pulley is 2. (b) Why is a single fixed pulley is commonly used in spite of the fact that its mechanical advantage is less than 1? (3) (ii) A person of mass 60kg can develop a power of 240W. If the person runs up a flight of n stairs each measuring 20cm in 15 s, calculate the value of n . (Take g= 10m/s2) (3) (iii) Complete the diagram and find the focal length and radius of curvature of the given lens. Name the lens. (4) O I 2cm 1cm 3.5cm Q6. (i) Two lamps one rated 220 V, 50 W and the other rated 220 V, 100 W are connected in series with the mains of 220V. Which lamp will glow brighter and why? (3) (ii) (a) Name the process by which the sun produces its energy. (b ) Give any two disadvantages of Hydro energy. (3) (iii) A pulley system can lift a load of 1200N by an effort of 250 N. If the resistance due to weight of movable part and friction is 300N, calculate the (4) (a) Mechanical advantage (b) Velocity ratio (c) Total number of pulleys in the system (d) Efficiency of the system Q7. (i) What are damped vibrations? Draw a displacement time graph of a damped vibration. (3) (ii) The refractive index of diamond is 2.42. What is meant by this statement? (1) (iii) State Snell s law of refraction of light. (2) (iv) A metal drill of power output 500W drills a hole in a lead cube of mass 0.25kg is 6.5s. The specific heat capacity of lead is 130J/kg C. Calculate the (4) (a) Heat generated by the metal drill in 1s. (b) Heat generated by the metal drill in 6.5s. (c) Heat absorbed by the lead cube in terms of t if t C is the rise in temperature of the lead cube. (d) Value of t. Q8. (i) (a) write two important precautions that should be taken while handling radioactive materials. (b) State one use of radioisotope. (3) (ii) Draw an I-V graph to differentiate between ohmic and Non ohmic conductor (3) (iii) The given figure shows a battery having an e.m.f of 9V and internal resistance of 0.6 , connected to three resistors A, B and C. 9V A B 4 2 C 6 (a) Calculate the total resistance of the circuit. (b) Calculate the current in A and C resistors. (c) Calculate the potential difference across B and C resistors. (4) Q9. (i) (a) Name the device use to protect the electrical circuit from overloading and short circuits. (b) On what effect of electricity does the above device work? (2) (ii) State the principle of caloriemety . (2) (iii) State the conditions for a body to be in equilibrium. (2) (iv) 4 tube lights of 40 W each and two fans of 100 W each are connected to 200 V mains and operate on an average 8 hour a day. If energy cost Rs. 1.50 per kWh, calculate (a) The monthly bill of August month and (b) Minimum fuse rating. (4) Q10. (i) Write three properties of Becquerel rays. (3) (ii) A truck weighing 1000kg changes its speed from 36 km/h to 72km/h in 2 minutes. Calculate the work done by the engine and its power. (3) (iii) Draw a neat and labeled diagram of a cathode ray tube. (4) ---------------------------------------
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