Formatting page ...
PHYSICS SCIENCE PAPER 1 (2 hours) Answer 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 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 in Section I and any four of the questions from Section II.. The intended marks for questions is given in the brackets [ ]. SECTION I (40 marks) Question 1 (a) The diagram given below shows a fishing rod. (i) Copy the diagram and indicate the direction of load, effort and fulcrum. Also, state the class of lever this belongs to. (ii) Mention another simple machine present in the fishing rod. [2] (b) Consider the following system of pulleys. This system is used to lift a load of 400 N against gravity. (i) State the purpose of the pulley P. (ii) Calculate the mechanical advantage and the velocity ratio of the system if the efficiency of the system is 80%. [2] (c) A uniform meter rule is balanced by masses of 24 g and 16 g suspended from its ends. Where is the position of the pivot? [2] (d) A body is thrown vertically downwards from a height of 16 m. A graph between the height above the ground and energy of the body is plotted as shown. (Ene rgy) (i) What does OA represent? Calculate the mass of the body from the graph. (ii) Also, calculate the velocity with which the body reaches the ground, stating appropriate reasons. [2] (e) Give one example for the following energy conversions: (i) Chemical energy to mechanical energy. (ii) Heat energy to electrical energy. [2] Question 2 (a) (i) What is the maximum angle of refraction when light travels from glass to air? (ii) When does Snell s law of refraction fail? [2] (b) A given ray of light suffers minimum deviation in an equilateral prism P. Additional prism Q and R of identical shape and of the same material as prism P are now added in the figure. (i) What will be the angle of emergence if the angle of incidence on the prism P is 40 ? What will be the angle of deviation of the emergent ray? (ii) Trace the path of the monochromatic ray of light incident on prism P through the prisms P, Q and R. [2] (c) A lens has a magnification of 2.7. Giving suitable reasons answer the following: (i) Is the image real or virtual? (ii) What kind of lens is this? [2] (d) (i) Clouds in the sky are seen to be white. Why? (ii) What kind of envelope do mercury vapor lamps have? Why? [2] (e) A 660 Hz tuning fork sets up a vibration in a string clamped at both ends. The wave speed for a transverse wave on this string is 220 m/s and the string vibrates in three loops. (i) Find the length of the string. Where is the string plucked? (ii) Draw a suitable diagram of the wave in the stretched string. [2] Question 3 (a) A trombone is a brass instrument which has a sliding mechanism that varies the length of the metal tube. Giving suitable reasons, state which of the following produces a sound of more pitch, A or B. A B [2] (b) If the readings of the ammeter A1 is 2.4 A, what will the ammeters A2 and A3 read? Neglect the resistances of the ammeters. [2] (c) Water in an electric kettle connected to a 220 V supply took 5 minutes to reach its boiling point. How long would it have taken, if supply had been 200 V? [2] (d) (i) How does Lenz law justify the law of conservation of energy? (ii) Shown below is a setup of an experiment done by famous physicist Barlow. It is also known as Barlow s wheel experiment. Observe the diagram carefully. State the direction in which the wheel will rotate. [2] (e) State two advantages of the use of MCB over a normal fuse. [2] Question 4 (a) Name one component of wiring system which works under the principle of: (i) Heating effect of current (ii) Current will flow through the path of least resistance [2] (b) Consider the given wire. Determine the direction of flow of current, by using a diagram. It is known that the magnetic field at the center points towards you. [2] (c) 5 g of water at 30 C and 5 g of ice at 20 C are mixed together in a calorimeter. Find the amount of ice melted. [Take specific heat capacity of ice = 0.5 cal/g C; specific latent heat of fusion of ice = 80 cal/g] (d) Comment on the following statements giving appropriate explanations. (i) [2] [2] A fusion reaction is more energetic than a fission reaction. (ii) The sun is continuously losing mass. (e) Copy and complete the following nuclear reactions: (i) 31 15 + (ii) 919 + 11 27 (iii) 13 + 24 (iv) 36 + 10 [2] (?) + 10 (?) + 24 30 14 + (?) (?) + 13 SECTION II (40 marks) Question 5 (a) Two persons A and B carry a load of 1000 kg by hanging it on a pole, supported on their shoulders. A can exert a force 4 times as much as B and the pole is 2.5 m long. (i) Draw a diagram of this arrangement. (ii) Where should the load be suspended? (iii) Calculate the magnitude of forces exerted by A and B. [3] (b) A small block of mass 200 g is kept at the top of a frictionless incline which is 10 m long and 3.2 m high. How much work is required if: (i) Calculate the work required to lift the block from the ground and put it at the top. (ii) Calculate the work required to slide the block up the incline. (iii) Find the speed of the block if it falls of the incline and drops vertically on the ground. (iv) Find the speed of the block if it slides down the incline. [Take g = 10 m/s2] [4] (c) A woman draws water using a water pump as shown in the diagram given below. The length of the handle (AB) is 1.35 m and that of the pumping rod (AC) is 33.75 cm. Stating your assumptions, Calculate: (i) The external force required to lift 7 liters of water. (ii) The power at which the pump works if the force in (i) is applied with the velocity of 8 m/s. (iii) The power rating of the pump, if the efficiency of the pump is 75%. [Take density of water = 1000 kg/m3] [3] Question 6 (a) A ray of light PQ is incident on a glass prism ABC having the vertex angle A equal to 40 . The face AC is silvered and the ray of light is incident on the surface AB such that it retraces its path. Q Q P (i) Given that the refractive index of the prism is 1.28, calculate the angle of incidence of the surface AB. (ii) What is the angle of incidence on the surface AC? (iii) Complete the path of the ray PQ till it emerges out of the prism. Mark all the necessary angles in your diagram. (iv) What principle is shown through this problem? State the principle. [4] (b) A kind of lens is used to obtain a magnified image of an object on a screen 10 cm from the lens. If the magnification is +19, Find: (i) The kind of lens and its focal length. (ii) The power of the lens. (iii) Draw a neat ray diagram of this case and mention one use of this action of the lens. [3] (c) The following table gives value of the angle of deviation for different value of the angle of incidence for a triangular prism. Angle of incidence 33 38 42 52 60 71 Angle of deviation 60 50 46 40 43 50 (i) For what value of the angle of incidence, is the angle emergence likely to be equal to the angle of incidence? (ii) Draw a ray diagram showing the passage of ray of light through the prism, when the angle of incidence is of the above value. (iii) Draw a properly labelled graph between the angle of incidence and the angle of deviation. Show the value of your answer (i) in your graph. [3] Question 7 (a) A wave of frequency 4.5 MHz are used to detect tumor in soft tissues. The speed of sound in the tissues is 1.5 km/h and that in air is 340 m/s. (i) Identify the wave used. Give reasons for their use for the above purpose. (ii) Find the wavelength of this wave in air and in tissue. [3] (b) (i) State the conditions necessary for an echo to be heard distinctly. (ii) A train approaches a tunnel surrounded by a cliff. The driver sends a short whistle when 1.665 km away. The echo reaches him 9 seconds later. Find the speed of the train if the speed of sound in air is 340 m/s. [3] (c) The given setup consists of a tin can filled with sand and tethered to a rigid support R . Another thread with a free end F is tied with a magnet M , which is clinged to the surface of the tin. It is found that, by exerting small forces on the free end F , without making the magnet M fall, you can make the tin swing back and forth in very large swings. (i) Give reason for the above observation. What phenomenon is observed in this setup? (ii) What instrument is the tin and the thread simulating? Mention a way to measure the frequency of this swing. (iii) What kind of vibrations are applied to the free end of the string? How does this vibration differ from the free vibration of the tin tethered to the string? [4] Question 8 (a) A source of heat supplies heat at a constant rate to a solid cube. The variation of the temperature of the cube is shown in the figure given below: (i) What does the parts AB and CD represent? (ii) If CD = 2.5 AB, what does that mean? (iii) What does the slope of the part DE represent? (iv) What conclusion would you draw from the fact that the slope of OA is greater than that of BC? [4] (b) The temperature of a brass cylinder of mass 100 g was raided to 100 C and transferred to a thin aluminum can of negligible heat capacity containing 150 g of paraffin at 11 C. If the final steady temperature after stirring was 20 C, calculate the specific heat capacity of paraffin. Neglect heat losses. [Take specific heat capacity of brass = 380 J/g C] [3] (c) Copper nails weighing 100 g heated to 100 C are dropped into a calorimeter of mass 100 g containing 40 g of a mixture of ice and water. If the resulting temperature is 10 C, find how much ice is present. [Take specific heat capacity of copper = 0.09 cal/kg C, specific latent heat of fusion of ice = 80 cal/g] [3] Question 9 (a) The headlights of a car can be connected in two ways as shown below. Which circuit would you recommend and why? [3] (a) Jatin is examining certain substances with specific characteristics. Observe the properties of the substances and help Jatin answer the following questions. Substance X B Z A Y C (i) Properties High specific resistance. Resistance increases with increase in temperature. Low melting point. Specific resistance is greater than that of copper. Zero resistance. High resistance and high melting point. High specific resistance. Resistance remains constant with increase in temperature. Very high resistance. No current can pass through. Why is the specific resistance of B greater than that of copper? Where is it used? (ii) Identify Z. What do you mean by the property zero resistance? (iii) Which of the given substances would you recommend to use as a heating element in an iron box? Justify your answer. (iv) Which of the given substances is best for using as a standard resistor? Identify the substance. [4] (a) A 3.0-ohm resistor, an unknown resistor, R, and two ammeters, A1 and A2, are connected as shown below with a 12-volt source. Ammeter A2 reads a current of 5.0 amperes. (i) [3] Determine the equivalent resistance of the circuit. (ii) Calculate the current measured by the ammeter A1. (iii) Calculate the resistance of the unknown resistor R. Question 10 (a) The following figure shows a rectangular coil ABCD placed in between the pole pieces of a horse-shoe magnet with its plane perpendicular to the magnetic field. A battery is connected to the ends D and A of the coil. (i) Name the part that implies whether the given motor an A.C. type or D.C. type. Redraw the diagram with the stated part and label the parts. (ii) State two factors on which the torque produced depends. If BC = 4 cm and a force of 5 N acts on both sides (AB and CD) of the coil, calculate the torque produced and state the direction of rotation. (iii) If the coil rotates 42 times a minute and does a work of 4 J per rotation, calculate the power of the coil. If the current in the circuit is 1.4 A, calculate the e.m.f. of the cell. [4] 230 (a) A thorium isotope ( 90 ) undergoes an alpha decay and changes into radium. (i) What is the atomic number and mas number of the radium produced? (ii) If the radium further disintegrates and emits two beta particles, represent this reaction in the form of an equation? (iii) What is the source of energy released during the decay? [3] (b) The controlled reaction between deuterium and tritium has involved ongoing research for many years. The reaction may be summarized as: 12 + 13 (i) + 10 Find the values of X, P and Q. (ii) Why cannot this reaction be carried out in the laboratory? (iii) What research is being done pertaining to this kind of reactions? [3]
|
