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SMT SULOCHANADEVI SINGHANIA SCHOOL, THANE STD SUBJECT EXAM MARKS TIME NO OF PAGES DATE 10 PHYSICS PRELIM 80 2h 7 1811124 SECTION 1 ANSWER ALL THE QUESTIONS IN THIS SECTION Question 1-Choose the correct alternative: 1. The centre of gravity of a regular object would lie b. in the body a. on the body d. all the above c. outside the body (15) --- 2. Choose the correct meaning of the statement: "The efficiency of a machine is 60%". a. In the given machine M.A. > V.R. b.60 % of the total energy supplied is obtained as useful energy. c. 60. % of the total energy is lost in overcoming the force of friction. d.The power output is more than the power input. 'h' holds a heavy 3. A construction worker standing in the ground floor of a building of height worker in those the by done is work much How tool box of mass 'm' in his hand for 2 hours. two hours? a. mgh b. mv2 c. 2mgh d. zero 4. When a ray of light enters from denser _to rarer medium then: a. the light ray bends towards the normal _ b. the speed of light increases the angle of refraction than greater c. the angle of incidence is d. its wavelength decreases =0.9. If a light ray is 5. Refractive index of medium A with respect to medium Bis given as eJJA incident, making i >0 _from B to A. a. It will suffer only total internal reflection b. It will bend away from normal c. It will bend to,wards normal d. It will go _ undeviated abilities of alpha and 6~ Which row correctly shows the relative ionizing effects and penetrating beta particles? Ionising effect Penetrating ability a>f3 a>f3 B a>f3 a<l3 C a<f3 a>f3 D a<f3 a<l3 a. A b.B A . d.D c.C 1 , . . -. edlum In which their speed is V into a med\\.Jm '" " 7. Sound waves of wavelength 1' travel from :e sound in the second medium Is: which their speed ts 4V. The wavelength O d. 41' 31' a. /\ b. 21' c. h " 8. Which type of lever is used in the human body w a. Class I Lever b. Class II Lever c. Class we raise the body weight on our toes? d. Class IV Lever Lever . I d with the same area of cross section. 9. There are two unequal lengths of Identical matena an . Which one of the following sentences is correct? a. Both wires have the same resistance. b. The wire of greater length has greater resistance. c. The wire of greater length has the lower resistance. d. The given data is not sufficient to infer the answer. 10. For the given cooling curve, the latent heat is released in which stages? j~ .5 250 200 150 .X.E "" 100 so A " 0 a. b. . c. d. r R S 10 15 " 20 D 25 E ' 30 35 BC and DE CD and EF BC and CD AB,CD and EF 11. When seven spectral colours pass through a glass block from air, then which ones of the following statement is correct . a. In the glass block, speeq,,of blue light > speed of yellow light b. in the glass block, sP ,q. bf green light > speed of orange light J., c. In the glass block,,~P,eed of violet light > speed of red light d. In the glass b.lodk, ,.s.peed of orange light> speed of indigo light I 12. Which circuit s~ows the correct and safe positions for the fuse and the switch? E3 / A NUblwirt E3 fllunlwira ,} C fllUQlwq E3 2 } ' } 13. A circuit contains two resistors connected In parallel with an ideal battery of emf E as shown In figure. Name the points where current Is maximum and minimum: r - - - - t ~ - 1 ' - - - - - - , R p a. P and R 2 l c. Q and R b. Rand P d. Rand Q 14. A sonar echo takes 4.4s to return from a submarine. If the speed of sound in water is 1500m/s then the distance of submarine from the sonar Is: 1500m a. 3000m b. 3300m c. 3600m d. 15. In each of the following questions, statement of Assertion (A) is given followed by a corresponding statement of Reason(R). Assertion(A): The loudness of sound depends only on its amplitude. Reason(R): When the amplitude of vibration is large, sound produced is loud and when the amplitude of vibration is small, sound produced is feeble. Select the correct option below: Both (A) and (R ) are true and (R) is the correct explanation of (A) a. Both (A) and (R ) are true but (R) is not the correct explanation of (A) b. (A) is true but (R ) is false. c. . (A) is false but (R ) is true. d. 15 Question 2 A.(l)Name the type of transformer shown Qelow. (ii) In this transformer which winding(primary or '(3) secondary) is made thicker and why? ,0 B . GiveJwo points of difference between a de motor and ac generator. . ' C. Why the earth pin in a 3 pin plug is made longer and thicker. D. In the figure below P,Q,R same string showing 3 modes of vibrations between two same fixed ends: (i) Which out of the three has the highest frequency? Why? (ii) How the vibrations in 3 situations are related in terms of their frequencies. p CX:..X Q 3 R E.The diagram shows the cooling curve for 200 g of water.The heat Is extracted at the rate of 100 J/s.Answer the questions that follow: (I) Calculate the specific heat capacity of wate r (II) Calculate the heat released in the region BC. f "' V !IO'O A il...,,_ ' ' v-v ; , - . - - - - - ~C : . . (0.0) l40 1S12 . . (I) I F. Name the material of the prism required for obtaining I G Whe n the c,rcu1 t is switc hed on, the . ammeter reads 0.5A.(I) .Calculate the value of the unknown res1stor R.(ii) Calculate the power dissipated in the 3Q resistor. I the spectrum of:(i) ultraviolet(ll)Jnfrared. - e-ov , . . R Question 3 (10) A.The diagram alongside shows a force F =~ N acting at point A produces a moment of force of 6 Nm about point 0. What is the diamet~,r ofthe wheel? .. B.'Each wire in a :cable can only withstand a certain amount of current. If the current exceeds this limit (due t0:s11ort-circuiting or strong voltage fluctuations), the wire may overheat and bum, resulting:Jn .a- fire.To avoid this, a specific wire known as the high tension wire is utilized for high ~- ,~... vol~g~ and strong current. Sfat~:two characteristics of these high tension wires. ,1.1., . c. A force is applied on a body of mass 20 kg moving with a velocity of 40 ms 1 The body attains a velocity of 50 ms 1 in 2 seconds. Calculate the work done on the body in those 2 seconds. D. Out of the three connecting wires in a hous ehold cir~uit. (I) Which two of the three wires are at the sa~e potential? (II) In which of the three wires should the switc h be connected? 4 f. From the adjoining diagram, answer the questions that follow: r (i)What kind of pulleys are A and B? (ii) State the purpose of pulley 8. (iii) What effort has to be applied at C to just raise the load L = 20 kgf(Neglect the weight of pulley A and friction). SECTION 2 Answer any 4 out of 6 questions in this section 3+3+4=10 Question 4 A.(i) Draw the schematic diagram of the class of lever that has MA>1. (ii) Why are the passengers not allowed to stand in a small boat while crossing a river? B. (i) Give an example when work done by force of gravity is zero.even though the body gets displaced from its initial position. (ii) A light and a heavy body have equal kinetic energy. Which has larger momentum? C. (i) Where does the centre of gravity of a_ hollow cylinder lie? (ll)A uniform metre rule balances horizontally on a knife edge placed at the 58cm mark _ when a weight of 20gf is suspended from one end. Draw the diagram of the arrangement and calculate the weight of the rule. Question 5 3+3+4=10 A.(i)A lens produces a virtual image between the object and the lens.Name the lens. (ii)A boy uses the blue colour of light to find the refractive index of glass. He then repeats the experiment using the red colour of light. Will the refractive index be the same in both ~ses? Justify. B. A ray of light passes through a right angled isosceles prism as shown below. B C A (i)What is the angle through which the incident ray deviates and emerges out of the prism? (ii) Name the instrument where this action of the prism is put to use. (ill) Which prism surface will behave like a mirror? C. An object is placed at a distance of 12 cm from a convex lens of focal length 8 cm. Find: (I) the position of the image (ii) nature of the image (iii) magnification 5 Question 6 A. A ray of light travels from water to air as shown In the diagram given below: 3+3+4=10 Air Water (i) Copy the diagram and complete the path of the ray. (Given: the critical angle for water is 48 ). (II) What do you understand by the term critical angle? B. (i)What is the relationship between the commercial unit of energy and SI unit of energy. (ll)A ball of mass 0.2 kg is thrown vertically upwards with an initial velocity of 20 mis. Calculate the max PE it gains as it goes up. C. Name any two electromagnetic waves which have a wavelength higher than that of violet light. State one use of each. A Question 7 3+3+4=10 A. (i) State any one disadvantage of connecting appliances in series. (ii) Calculate the electrical energy in kWh consumed in a month, ,fr,- a house using two bulbs 100W each and a fan of 75 W, if they are used on an average of 10 h each day. If the cost per unit is Rs 4.50, calculate the electric bill to be paid per month. B.(l)What is the function of earthing an appliance? (ll)ldentify and write Live, Neutral and Earth a,gainst the correct number . 2 c. The I-V graph oftw~ wires A and Bis shown below. (I) Calculate the.:r~sJstance of both wires. (ii)Compare-.tneir..,conductance. (ll)Give the SJ.-unit of conductivity. T I (mA) A B 100 2 3 V (V) 6 ) 3+3+4=10 Question 8 A. In the given figure S Is a radioactive substance. (I) Label all parts 0, A, Band C. (ii) What is the importance of part 0. (Ill) Why C has greater bending than B? A C by B. (i)When 1g of ice at 0 C melts to form 1 g of water at O c then, is the latent heat absorbed the ice or given out by It? (ii)Explain why the weather becomes very cold after a hailstorm. 0 C.(i) Differentiate between heat capacity and specific heat capacity(one point ). J/kg C (ii)You have a choice of three metals A,B and C, of specific heat capacities 900J/kg C, 380 your Justify select? you will material. Which r. and 460J/kg C respectively, to make a calorimete answer. Also state which of the three metals is a good conductor of heat. 3+3+4=10 is A. 2 pendulums C and D are suspended from a wire as shown in the given figure. Pendulum C . made to oscillate by displacing it from its mean position. It is seen that D also starts oscillating (I) Name the type of oscillations C will execute. (ii) Name the type of oscillations D will execute. s of (iii) If the length of D is made equal to C , then what difference will you notice in the oscillation Question 9 D? ----- --wi re D C B.(i) Name the factors that determine the quality and pitch of a note. (ii) State one factor on which the frequency of sound emitted due to vibration in air column depends. C. A certain nucleus X has a mass number 14 and atomic number 6. The nucleus X changes 14 Y after the loss of a particle. (i) Name the particle emitted. (ii) Represent this change in the form of an equation. its (Ill) A radioactive substance is oxidized. What change would you expect in the nature of radioactivity? Give a reason for your 1 ........... ........... ........... ........... ........... ........... ........... ........ 7 to
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