Formatting page ...
DELHIPUBLIC SCHOOL NEWTOWN SESSION 2024-25 PRE BOARD EXAMINATION FULL MARKS: 80 TIME: 2 HOURS CLASS: X SUBJECT: PHYSICS (SET A] Answers to this Paper must be written on the paper provided separately. You will hot be allowed towrite during the first 15 minutes. This time is to be spent inreading the question paper. The time given at the head of this Paper is the time allowed for writing the answers. Section Ais compulsory. Attempt any four questions from Section B. The intended marks for questions or parts of questions are given in brackets l): This paper consists of eight printedpages SECTION A Question 1 [15 x 1- 15] Choose the correct answers to the questions from the given options: (Donot copy the question, write the correct answers only.) (i) The diagrams below show 5N force is acting on a rod AB pivoted at A in different directions. ldentify the correct statement. SN 25 cm 25 cm (P) 25 cm B (R) (Q) SN 25 cm 5N (S) 5N (a)the moment of force in R is negative. (b) the magnitude of the moment of force is maximum in R. (eP and Q have opposite moments. (d) the magnitude of the moment of force is maximum in Pand Q. (i ) A solid cone A, a holow cone B, and a solid cylinder C, all have the same height of 12 cm. The positions of their centers of gravity from the base are calculated. Which of the following shows the correct sequence of the positions of the centers of gravity from the lowest to the highest? (b) B<A<C Va) A <B<C { i) The energy change that takes place in a thermocouple: (a) electrical to heat (b) mechanical to heat fo heat to electrical (c) heat to mechanical (iv) (d) A<C<B (c) C<A<B The adjacent diagram shows the movable block of a block and tackle system. The direction of effort is not specified. What could be the probable mechanical advantage of the system? (b) 5 (d) both (a) and (b) (c) 3 A/1 (v) (vi) to : A star appears twinkling in the sky. This phenomenon is due Jrefraction of light (a) reflection of light (c) total Internal Reflection (d) dispersion of light The critical angle for water-air is 49 for green light. The (Ness than 490 light eritical angle for red (c) equal to 49o (vii) will be: more than 490 (b) insufficient (d) data The focal length of a concave lens is 20 cm. What willbe its maximum image distance : (a) 10 cm (b) 20 cm eyanywhere between 10 cm and 20 cm. (d) cannot be determined from the given information (viii) Assertion : The focal length of a lens does not change when red light is replacedby blue light. Reason: The focal length of alens depends on the refractive index of material of lens. (a) both A and R are true and R is the correct explanation of the A. (b) both A and R are true and R is not the correct explanation of the A. LoA is false but R is true. (d) Ais true butR is false. (ix) String is thicker than String Y. If both are under the same tension, which of the following is true for them to produce the same pitch? ) string X must be longer than String Y. (b) string X must be shorter than String Y. (c) both strings must have the same length. (d)the length of the string does not matter. (x) The temperature (T) dependance of resistivity of materials A and B is represented by fig (i) and fig (i) respectively. Identify material A and material B. 1 p T lig. (i) (a) A- copper, B- germanium (c) A-nichrome, B-germanium (xi) T lig. (ii) L A-germanium, B-copper (d) A-copper, B-nichrome In electrical wiring, specific colors are used to indicate the of of the following statements correctly describe the standardfunction color codingdifferent for (a) the yellow wire is used as the neutral wire, while the blue wire is wires. Which wires? the live electrical wire. blue wire is used as wire. the neutral while live wire, as the (c) the black wire is used the red wire is (d) the brown wire indicates the ground Iconnection, and the redused for wire is neutral. connection. used for the live A/2 (bythe green wire is used for grounding or earthing, while the CD. two coils PO and between in arrow by the moved indicated direction the is Abar magnet Predict the directions of induced current in each coil. (xii) (a) anticlockwise in PQ and clockwise in CD (b)clockwise in PQ and clockwise in CD (c) anticlockwise in PQ and anticlockwise CD ( clockwise in PQ and anticlockwise in CD of the same mass having specitie Same amount of heat is added to two substances A and B (xii) statement. heat capacities S, and s, Such that s, > s,. Select the correct temperature B. (a) the change in temperature ofA is more than the change in temperature B. (b) the change in temperature of A is less than the change in (c) both will have the same change in temperature. capacities. (d) temperature changes are not related to the specific heat (xiv) substances, one made of ice and the other made different of blocks identical two given You are If the same amount of pressure is applied to of wax, both at their respective melting points. ice and wax? (b) increases, decreases both,which option is correct for the melting points of (a) decreases, increases (d) both increases (c) both decreases (xV) Z3Nay and "Mg2 are the examples of; (a) isotones (b) isotopes (d) both isotones and isobars (c) isobars Question 2 answers from the bracket: Complete the following by choosing the correct (i) measures electric energy in the units of (a)The electricity meter installed in our home [kW/kWh/J) (b) A movable pulley is used as a |6| [force/ energy/speed] multiplier. deviate (c) Atotal reflecting equilateral prism can be used to a ray of light through (30 /60 /90 ] resistance and 3 mm, will have the ratio of (d) Two copper wires having radii 2 mm [4:9, 2:3, 9:4]. Jat F, /at 2F, /beyond 2F;] in a terrestrial telescope, (e) The image is formed lat infinitylat 2F,/beyond 2F,). but in a slide projector the mage is (ii) (iii) formed resistance Draw a graph showing the variation of the radius other variables remain constant : (a) the (a) Name the radiations used for studying (b) Mention one of its properties. A/3 of a wire with the following, when (b) length atomic arrangement in crystals. [2] Question 3 the () (a) Aglass slab is placed in the path of a parallel light beam before itt is passingthrough |2| lens, as shown in the figure. Where will the rays meet after passing throughthe lens. (b) The power of a lens is +2.0 D. Identify the lens. (ii) In the following diagram, two people are touching similar appliances. Identity in wne diagrams- (a) or (b) the person is getting a shock? Justify your answer. {2| Ase 230v Ruse 230V la) (ii) We always connect a charger to mains to charge our mobile phones. A transformer is used for the purpose. (a) Identify the type of |2| transformer used for the above purpose. (b) State its turns ratio. (iv) (V) (vi) A solid of mass 80 g at 100 C is placed in 55 g of water at 35 C. The final 45 C. Calculate the heat is capacity of the solid. [sp. heat capacity of water istemperature 4.2 JgK'| 12| (a) What is the function of the split ring in a DC motor? commutator (b) Name the SI unit of the strength of the |2| magnetic field. (a) What is the origin of -particles? (b) Show its emission by means of an equation. (vi) 12] Tara, after completing her exams, went to her grandmother's brother Rahul. One day, Rahul came homne after playing and conditioner. At the same time, his grandmother was mixer. Suddenly, they heard a big sound and the preparing a Tara called an electrician. He said that the main electricity in the reason for the overloading. (a) What is overloading? (b) Are overloading and short circuits the same thing? house along with switched on the fanherandyounger air mihouse lkshakegotforshuthim supply to shut using a down. down was (c) When does short circuit happen? (31 A/4 (ii) refractive and reflection of air) Aray R, is in partial (kept on incident the plane surface of the glass slab undergoesreference tothe index V2 at an angle of incidence a', The refracted ray R, the refraction at the other surface. Complete the following tablewith question and the diagram. One is done for you. Sr. no. quantity value 1 2 30 3. R3 R2 b 4. S. R4 angle of deviation between R, and Rd Question 6 [3+3+4] A metal rod AB of length 80 cm is balanced at 35 cm from the end A with weights suSpenue from the two ends as shown below. 35 I009f (ii) (iii) 40 Fulcrum 5ogt (a) Find the weight of the rod. (b) State the principle that you have used here. For each of the following situations, state whether the work done by gravity is negative or zero. positive, (a) satellite orbiting the earth. (b) throwing a ball upward. (c) a child sliding down a slide. A ball of mass 2 kg slides down the figure. inclined plane as shown in the (a)The maximum velocity acquired by the ball is 6 m/s. Find the height 'h'. [g=10 N/kg| \ n (b) What is the total energy at the mid point of AC? (e) Draw an energy versus distance graph as the ball n,65 falls down from A to C and mark kinetic energy and potential energy in the graph. Ques+on 7 () d Ablock and tackle pulley system containing 4pulleys has is lifted by the pulley system. (a) Find the effort needed to overcome the load. A/6 h ,8 C efficiency 80%. Aload of 320|3+3+4| kgf else can you (b) You can reduce friction to increase the efficiency for this design. What get greater efficiency for this design? do to speed of after 4 seconds. If the echo the hearing shouts, and wall large A person stands near a (ii) the sound in the air is 343 m/s. wall. (a) Calculate the initial distance between the person and the when they shout again the echo and wall, the from awav farther moves then person moved from (0) The how much further the person has C'alculate before. than longer lakes 1.5Seconds 19n-25m the walI. John was doing an experiment in the laboratory with four test each tubes A, B, C and D, each with a height of 20 cm. He filled (iii) - 16 tube with water at different levels, A - 12 cm, B- 14 cm, C tuning fork cm, D - 18 cm respectively. He then took Davibrating heard a loud and placed it near the mouth of test tube and however he sound. He tried the same thing with other tubes, C following: didn't hear any loud sound. Answer the D. with tube (a) Name the phenomenon that happens tube D? n test with heard (b) Why was the loud sound occurred with other tubes. . (c) Name the phenomenon that would want to hear a loud sound from all the tubes? ? (d) What needs to be done if he Question & variation of terminal The folowing graph shows the () (3+3+4] a potential difference V, across a cell to resistor, versus current I. Volt) (n gV Calculate: (a)emf (b) internal resistance A. (c) terminal voltage when current is 1.5 (ii) (iii) decay and nuclear fission. (a)Distinguish between radioactive a fissionable material? (b)Why is U-235 preferred over U-238 as The diagram alongside shows a circuit with the key K open. I in A 232 5! 3.3V. 0.S2 Calculate: (a)the current drawn from the cell when the key K is open. key K is closed. (b) the equivalent resistance when the resistance when the circuit is closed. (C) the current drawn through 5 ohm |3+3+4] Question 9 g of water at 80 C to cool it down to Wnat mass of ice at 0 C needs to be added to 3 latent heat of ice = 336J/g. Specific J0'C?Given: specificheat capacity of water = 4.2 Jig C. A/7 (ii) The diagram below shows a cooling curve for a liquid 10 J/s. Temperature ( C) transferredat Heatis of mass 10 kg. P200 150 100 50 0 10 15 20 25 30 35 Time (s) (a) Mention the range of temperature in which it is in liquid state. (b)Calculate the specific latent heat of of the liquid. (c) Why is steam at 100 C more painful,condensation causing burns than boiling water at temperature? (iii) te D The diagram below shows two solenoids A and B. A is connected with a rheostat, cell, and a switch. B is connected with a galvanometer. A R B S (a) When will you observe a deflection in A? (b) Mention one factor to change the amount of (A)Name the law that you have used to find the deflection. (B) Namne one device that works with this set up. direction of deflection of the galvanometer.
|
