» Expected Question : CBSE Sample Question Papers

Short/V. Short Answer Questions (1,2 Marks Questions)

1. Name the two factors which account for existence of atmosphere on the planet.
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2. How is the luminosity of a star affected by the increase in its mass ?
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3. Name the parameters which determine the apparent colour of a star.
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4. What is geostationary satellite ?
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5. What are meteorites ?
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6. How does a radar help in determining the distance of a distant object ?
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7- Write the sequence of steller spectra which arranges the states in order of decreasing tempera¬ture. To which steller class our sun belongs?
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8. Write the names of two superior planets.
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9. What are comets made of ?
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10. How do comets form tail ?
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11. Write down four points of difference between earth and Jupiter.
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[Short/V. Short Questions—1, 2 Marks Questions]

1. How does the conductivity of a semiconductor change with temperature ?
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2. In the following diagrams, indicate which of the diodes are forward biased and which are reverse biased ?
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3. Write the truth table for AND gate.
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4. In a circuit shown, a switch which is open represents logic state 0 and the switch is closed represents logic state 1. The lamp L is lit when output is in logic state 1. What type of gates are represented by circuits in (i) and (ii) ?
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5. The output of an OR gate is connected to both the inputs of NAND gate. Draw the logic circuit of this combination of gates and write its truth table.
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6. When the voltage drop across ap — n junction diode is increased from 0 • 65 V and 0. 70 V, the change in the diode current is 5 mA. What is the dynamic resistance of diode ?
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7. When the voltage across/? — n junction diodes is increased from 0 • 70 V to 0. 71V, the change in diode current is 10 mA. What is the dynamic resistance of the diode ?
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8. Write the truth table for OR gate.
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9. Draw a circuit diagram for use of PN junction as a half wave rectifier.
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10. Which biasing will make the resistance of p — n junction high ?
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11. Draw logic symbol for a NAND gate.
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12. Draw a graph showing the variation of current with voltage for p — n junction diode.
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[Short/Very Short Answer Questions-1, 2 Marks]

1. Name the series of hydrogen spectrum lying in ultraviolet region.
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2. The total energy of an electron in the first excited state of the hydrogen atom is about —3.4eV. What is the P.E. of the electron in this state ?
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3. What is Bohr’s quantisation condition for angular momentum of an electron in the second orbit ?
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4. What is a-particle ? In the reaction zX^A = a + Y, give the atomic number and mass number ofY.
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5. What is beta decay ? Give one example of this decay.
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6. Does the ratio of neutrons to protons in a nucleus increase, decrease or remain the same after the emission of an a-particle ?
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7. Write the number of protons and neutron in 56Ba
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8. Write the number of photons and neutrons in B.
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9. Why is the energy distribution of beta rays continuous ?
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10. What is the angular momentum of an electron in the 3rd Bohr orbit of an atom ?
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11. Write down the equation of decay of a free neutron.
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12. State Bohr’s postulates for explaining the spectrum of hydrogen atom.
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13. Write the relation connecting the radius R of nucleus and its mass number A.
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14. What is the difference between isotopes and isobars ?
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15. Define radius of nucleus.
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16. What is nuclear night ?
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17. What is nuclear holocaust ?
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18. Name two radioactive elements which are not found in observable quantity in nature.
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19. What is the ratio of radii of nuclei of mass A₁ and A₂ ?
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[Short/Very Short Questions-1-2 Marks)

1. Intensity of incident radiation on a metal is doubled, what happens to kinetic energy of electrons
emitted ?
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2. Calculate de Broglie wavelength of a body of mass 3 kg moving at 5 ms^-1
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3. What is the main features of a metal used for photoelectric emission ?
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4. Why de-Broglie wavelength of a mass on the earth is not noticeable ?
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5. The de-Broglie wavelength of a photon and an electron are the same. Which of the two has greater energy ?
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6. What happens to the velocity of the emitted photoelectrons if the wavelength of the light incident is decreased ?
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7. What is dimension and SI unit of Planck’s constant ?
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8. What is meant by Stopping potential ? How is it related to intensity of light ?
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9. What is the value of Stopping potential betweeen the cathode and the anode of a photocell, if maximum kinetic energy of an electron is 5eV ?
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(Short/Very Short Answer Questions-1, 2 Marks)

1. Doppler effect can help to decide whether a star is approaching or receding from earth. Explain how ?
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2. If two slits in Young’s experiment have widths in the ratio of 16:1, calculate the ratio of intensity of maximum and minimum in interference pattern.
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3. If power of a lens is + 5 dioptre, what is its focal length ?
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4. Why does a soap bubble show beautiful colours when illuminated by white light.
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5. State the conditions for the two light waves to be coherent.
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6. Will the reflected ray converge at a point when a parallel beam of light is incident on a concave mirror of large aperture ?
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7. Light of wavelength 6,000 A in air enters a medium of refractive index 1.5. What will be its frequency in the medium ?
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8. Two thim lenses of focal length 15 cm and 30 cm respectively are kept in contact with each other. What is the power of the combined system ?
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9. Copy the following diagram and complete it to show the rays emerging out of prism B.
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10. Describe with the aid of a labelled diagram, how the wavelength of monochromatic light may be found by Young’s double slit experiment.
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11. A slit of width a is illuminated by monochromatic light at normal incidence. Draw the intensity distribution curve due to diffraction.
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(Short/V. Short Answer Questions-1, 2 Marks)

1. What features of e.m. waves lead Maxwell to conclude that light itself is electromagnetic wave ?
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2. For an electromagnetic wave, write the relationship between amplitude of electric and magnetic field in free space.
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3. State tour properties or electromagnetic waves.
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4. Why sky waves cannot be used in television broadcasting ?
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5. What is the cut off frequency beyond which the ionosphere does not reflect electromagnetic radiations ?
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6. Give a diagram for which it is clear that “taller the antenna, longer the coverage of the television broadcast.”
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7. What evidence is there to show that sound is not electromagnetic in nature ?
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8. Why is it necessary to use geo-stationary satellite for telecommunication ?
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9. What oscillates in electromagnetic waves ? Are these waves transverse or longitudinal. 10. What was the range of wavelength of electromagnetic waves produced by Prof. J.C. Bose.
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12. wavelength of electromagnetic radiation is doubled. What will happen to the energy of photons ?
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13. Draw a labelled diagram of Hertz’s experiment for production of em waves.
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14. What is electromagnetic constant ?
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15. Arrange in descending order of wavelength y-rays, X-rays and visible light.
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[Short/V- Short Answer Questions-1, 2 Marks Each]

1. A vertical magnetic needle falls down through plane of magnetic meridian. Will any e.m.f. be produced between its ends ? Give reasons for your answer.
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2. Sketch a graph showing the variation of reactance of a capacitor with frequency of applied voltage.
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3. A small magnet is pivoted to move freely in the magnetic meridian. At what place on the earth’s surface will magnet be vertical ?
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4. A choke coil and a bulb are connected in series to a D.C. source. The bulb shines brightly. How does its brightness change when iron core is inserted in the choke coil ?
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5. Which device will you use to step up an a.c. voltage ? Can we use the same device to step up d.c. voltage ?
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6. The e.m.f. of an a.c. is given by the equation
E = 300 sin (314t) Write the values of heat voltage and frequency of the source.

7. What is the cause of E.M.I ?
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8. What is right hand rule ?
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9. Why are transformer are laminated ?
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10. What is dead beat galvometer ? How is this realised in practice ?
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11. Define henry
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12. How are coils of resistance box wound ?
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13. What are units of R/L and CR ?
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14. What is the rate of growth of current in LR circuit?
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15. Explain LC oscillations in terms of energy transfer.
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16. What leads E or I in a circuit containing an inductor ?
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17. What is the power consumed in a pure inductive circuit connected to a.c. ?
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18. What is the role of back e.m.f. in d.c. motor ?
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19. How energy losses in transformer be reduced ? Give two such steps.
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20. What is the main difference in d.c. dynamo and d.c. motor ? Can they be used for both purposes.
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21. What is resonance ?
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(Short/V. Short Questions i.e. 1-2 Marks Questions)

1. Which direction would a compass point to if located right on the geometric north and south pole?
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2. Define neutral point. Write the positions of N.P. when a small bar magnet is placed with its north pole (i) towards north of the earth, (ii) towards south of the earth.
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3. What is the value of angle of dip at a place situated on the magnetic equator of the earth ?
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4. Define the term magnetic moment.
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5. Draw a diagram showing the lines of magnetic field around a bar magnet placed along magnetic meridian, with its north pole pointing towards geographical north.
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6. Distinguish between dia, para magnetic substances. Give one example each.
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7. Define angle of dip at a given place. What is the value of angle of dip on the equator ?
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8. If horizontal and vertical components of earth’s magnetic field are equal at a place, find the angle of dip.
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9. What is the difference between magnetic length and the length of magnet ?
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10. Give Gauss’s theorem in magnetism.
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11. Define magnetic equator, Is it the same as geographical equator ?
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12. What is underlined principle of a vibration magnetometer ?
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13. What are ferrites ?
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14. What is retcntivity and coercivity ?
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15. What is meant by reduction factor ? Define it.
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16. What is uniform magnetic field. How is it represented diagramatically ?
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17. Why cannot two magnetic lines of force intersect each other ?
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18. Define a magnetic line of force ?
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19. Why like poles repel each other and unlike poles attract each other ?
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20. What does result B . ds =0 signify ?
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21. How will compass stand in a field free area ?
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Short/V. Short Answer Questions 1-2 Marks Each

1. A current is set up in a long copper pipe. Is there a magnetic field (i) inside ; (ii) outside the
pipe ?
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2. Consider the circuit shown where APB and AQB are semicircles. What will be the mag¬netic field at the centre C of a circular loop ?

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3. Under what conditions the force acting on a charge moving through a uniform magnetic field., minimum ?
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4. What will be the path of a charged particle moving along the direction of a uniform magnetic field?
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5. An electron beam passes through regions of closed electric and magnetic fields of intensity E and B respectively! For what value of electron speed the beam will remain undeflected ?
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6. Write down the expression for the force on a current carrying conductor balanced in a magnetic field.
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7. State Fleming’s left hand rule.
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8. State Fleming’s right hand rule.
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9. Out of an ammeter and a voltmeter, which of the two has greater resistance and why ?
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10. An ordinary moving coil galvanometer used for dx. cannot be used to measure an alternating current even if the frequency is low. Explain why ?
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11. In a chamber of uniform magnetic filed B, an electron beam enters with a velocity by the
electrons.
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12. The coil of a galvanometer has a resistance of 100 Q. It shows full scale deflection for a current
of 5 X 10^-4 A. How will you convert it into a voltmeter to read P.D. of 5 V ?
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[Short and V/Short Answer Questions 1-2 marks]

1. State two factors on which temperature of inversion for a thermocouple depends.
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2. How is the electric conductivity of an electrolyte affected by increase in temperature ?
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3. Write the expression connecting the thermoelectric emf. of a thermocouple with temperature difference of its cold and hot junctions.
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4. Describe the term electrolysis. Give two factors which are responsible for lower electric conductivity of electrolytes than metals at room temperature.
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5. Current I flows through potential difference V across a conductor. What is the rate of production of heat ?
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6. Write the expression connecting thermoelectric e.m.f. for a thermocouple with temperature difference of junction ?
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7. Define the term electrochemical equivalent. What is its unit in S.I ?
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8. What is difference between Scebcck effect and Peltier effect 7
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9. What is the difference between Joule’s effect and Thomson’s effect ?
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10. Define Faraday.
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11. What is electricity consumed and cost of using 2 fans 55 watt each for 5 hours a day in September. 1 BOT costs Rs. 2.
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