CBSE Physics Sample Question Paper : Set-4
Q. I. What is the maximum value of the angle of dip?
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Q. 2. What is the resistance an ideal voltmeter?
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Q. 3. The refractive index of glass is 3 / 2 and that of water is 4 / 3. What is the refractive index of glass with respect to water?
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Q. 4. Half-life of a certain radioactive material against a-decay is 138 days. After what lapse of time the undecayed fraction of the material will be 6.25%?
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Q. 5. The angle of maximum elongation for the planet Venus is approximately 47°. Calculate in astronomical units and metre the distance of Venus from earth.
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Q. 6. What is shape of the trajectory of a-particle scattered in Rutherford’s experiment?
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Q. 7. The wavelength of electromagnetic radiation is doubled. What will happen to the energy of photons?
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Q. 8. State two reasons why electrolytes have lower electrical conductivity than metallic conductors in general.
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Q. 9. If the Young’s double slit experiment is immersed in water, how will the fringe width change?
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Q. 10. What are the dimensions of resistance?
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Q. 11. Draw a graph showing the dependence of intensity of transmitted light on the angle between polarizer and analyzer.
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Q. 12. A short bar magnet of magnetic moment 0.9 JT-1 (joule per tesla) placed with its axis at 45° with a uniform external magnetic field experiences a torque of magnitude 0.063 J. Find the strength of the mag¬netic field.
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Q. 13. Define resistivity of a conductor. How does it vary with temperature?
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Q. 14. A 10 Ω thick wire is stretched so that its length becomes three times. Assuming that there is no change in its density on stretching. Calculate the resistance of the new wire.
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Q. 15. Is photoelectric emission possible at all frequencies? Give reasons for your answer.
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Q. 16. Calculate the capacity of an isolated charged metal sphere.
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Q. 17. What is a comet? Why is the tail of a comet always pointed away from the sun?
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Q. 18. What is the basic difference between a magnetic dipole and an electric dipole?
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Q. 19. Explain why the sky appears blue?
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Q. 20. Give one use of each of the following:
(i) Microwaves,
(ii) infra-red waves, (iii) ultra-violet radiation, and
(iv) Gamma rays.
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Q. 21. The focal length of the eye piece of a certain microscope is 2.5 cm. The focal length of the objective is 16 mm. The distance between the objective and the eye piece is 22.1 cm. What is the linear magnification if the final image from the eye piece is formed at infinity?
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Q. 22. After charging a capacitor, the battery is disconnected. A dielectric slab is slipped between the two plates of the capacitor. What changes, in charge capacitances, potential differences and energy stored will be observed?
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Q. 23. Show that radioactive decay is governed by the law N (t) = N (o) e -λ t where N (o) is the number of radioactive nuclei at t = 0 and λ is a constant.
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Q. 24. Find an expression for the magnitude of the force on a current carrying conductor placed in a uniform magnetic field starting from the Lorentz’s force on a moving charge. On the basis of this expression define the direction of magnetic field.
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Q. 25. Find the electric field and the potential of the electric field due to two concentric spherical shells of radii R1 and R2 for a point whose distance from the common centre is r where (a) r>R2 (b)r< R1.
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Q. 26. A capacitor C is connected in series with a resistance R. A charge qo is given to the condenser. Show that the charge decreases exponentially with time constant RC.
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Q. 27. What do you mean by mutual inductance? What is its unit?
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Q. 28. Draw the intensity profile of interference fringes due to Young double slits of equal width.
In a Young’s double slit experiment screen is kept 100 cm from the slits. The third bright fringe is at a distance of 2.945 mm from the first dark fringe. What is the wavelength of the light used 3? The distance between the slits is 0.5 mm.
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Q. 29. Draw the circuit diagram of a voltage regulator circuit using a zener diode and explain its working.
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Q. 30. A sinusoidal emf is applied to a circuit containing an inductor only. Show that current lags behind the voltage by Π/2.
A coil has an inductance of 1 henry (a) at what frequency will it have a reactance of 3142 ohms? (b) What should be the capacity of a capacitor which has the same reactance at that frequency?
What is meant by the root mean square or effective value of alternating current? Derive a relation between it and its peak value.
The electric mains in the house are marked 220 V, 50 Hz. Write down the equation for instantaneous voltage.
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