CBSE Physics Sample Question Paper : Set-8
Q. 1. How does the atmospheric temperature change with altitude in the range 0-50 km?
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Q. 2. A wire of resistance 16 ohm is melted and drawn into a wire of half its original length. What is the resistance of the new wire?
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Q. 3. A dip needle lies in a plane perpendicular to the magnetic meridian, in what direction will it point?
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Q. 4. Give one practical application of thermoelectricity.
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Q. 5. The curves show voltage-current relationship for a photo—cathode illuminated by different sources of light. In what way the sources differ? In what way are they similar?
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Q. 6. The deflection of a galvanometer falls from 25 to 10 divisions when a shunt of 5 ii is connected across it. What is the resistance of the galvanometer?
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Q. 7. For the same angle of incidence the angles of refraction in three different media A, B and C are 15°, 25° and 35° respectively. In which medium is the velocity of light maximum?
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Q. 8. Electric charges q, q and - 2q are placed at the corners of an equilateral triangle of side /. What is the magnitude of the dipole moment of the system?
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Q. 9. When a battery of e.m.f. E and internal resistance r is connected to a resistance R, a current / flows through it. Derive a relation between E, I, r and R.
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Q. 10. Does an iron bar magnet retain its magnetism when melted? Give reason for your answer.
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Q. 11. A current of 5.0 A flows through an electric press of resistance 44 O. Calculate the energy consumed by the press in 5 minutes.
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Q. 12. A compound microscope has a magnification of 36. The focal length of its eye piece is 5 cm. Assuming the final image to be formed at the least distance of distinct vision (25 cm.), calculate the magnification produced by the objective.
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Q. 13. The Fig. shows an achromatic telescope objective made of two lenses, one of crown and other of flint glass, (i) Which of the two lenses has a larger focal length and why ?
(ii) The material of which lens has a larger dispersive power?
(m) Which of the lenses is made of crown glass and which one of flint glass?
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Q. 14. Derive an expression for the electric field intensity at a distance V from a point charge ‘q’.
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Q. 15. What is magnifying power for a visual optical instrument? Define it for a microscope.
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Q. 16. An electron beam is deflected in a given field. How will you detect whether the given field is a uniform magnetic field or a uniform electric field?
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Q. 17. A bridge circuit is shown in the Fig. It is to act as a full wave rectifier (i) where must the a.c. input be connected ? (ii) where will the d.c. output appear ? Indicate that current through the diodes after completing the diagram.
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Q. 18. Calculate the force per unit length on a long straight wire carrying of 2 A due to a parallel wire carrying 6 A current. Distance between the wires is equal to 3 cm.
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Q. 19. Explain how you will convert a galvanometer into an ammeter of a given range.
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Q. 20. A circuit consisting of a 12 V battery, a 2.7Ω resistance and a switch is opened. The internal resistance of the battery is, 0.3 Ω. What is the voltmeter reading (i) across the battery (ii) across the resistance (iii) across the switch? What are these values when the Switch is closed?
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Q. 21. The total energy of H atom when the electron is in the second quantum state is E2. What is the total energy of He+ ion in the third quantum ‘ state?
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Q. 22. A ray of light falls normally on the face of an isosceles prism u as shown. What is the minimum value of refractive index of the prism?
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Q. 23. The current gain of a transistor in common-base arrangement is 0.98. Find the change in collector-current corresponding to a charge of 5.0 mA in emitter-current. Find the change in the base current.
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Q. 24. A series LCR circuit with L = 5.0 H, C = 80 μF and R = 40Ώ is connected to a variable frequency source of 230 V.
(0 Determine the resonance frequency of the circuit.
(a) Obtain the impedance of the circuit and the amplitude of the current at resonance.
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Q. 25. An aeroplane having a wings span of 50 m is flying horizontally with a speed of 100 ms-1 at a place with an angle of dip 30°. (Earth’s total field is 4.0 x 10-5 Wb/m2). Calculate the induced potential difference between the edges of the wings.
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Q. 26. Show that the maximum magnifying power M of a simple microscope is given by:
M = 1 + D/f, where f = focal length and D = distance of distinct vision.
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Q. 27. Describe how the distance and size of a planet can be measured from the earth?
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Q. 28. Explain the phenomenon of glow discharge m a cathode ray tube. How are electrons knocked on of the cathode?
A coil of inductance 0.2 H and resistance 1.0 Ω is connected to a 20 V source (a) What is the rate of growth of current at the instant the coil is connected to the source (b) What is the current when the rate of growth is 100 A/s?
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