CBSE Physics Sample Question Paper : Set II
Q. 16. Figure (right side) shows an inductor L, a resistor R connected in parallel to a battery through a switch. The resistance of R is the same as that of the coil that makes L. Two identical bulbs are put in each arm of the circuit.
(i) Which of the bulb will light up earlier when S is closed ?
(ii) Will the bulbs he equally bright after some time ?
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Q. 17. A convex lens made up of a material of refractive index µ1is immersed in a medium of refractive index µ2. Trace the path of a parallel beam of light passing through the lens when (i) µ1 = µ2 ; (ii) µ1 < µ2 . Explain your answer.
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Q. 18. The wavelength of the second line of the Balmer series in the hydrogen spectrum is 4861 A. Calculate the wavelength of the first line.
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Q. 19. With the help of a circuit diagram explain how can you find the internal resistance of a primary cell. Derive the necessary formula.
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Q. 20. State and explain Huygen’s principle. Name the type of wave-front that corresponds to a beam of light (i) coming from a far off source ; (ii) diverging radially from a point source. 3
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Q. 21. Draw the logic symbol and truth table for an OR gate. Describe its realisation with circuit diagram using semiconductor diode.
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Q. 22. How will you determine the temperature of the sun ? Derive the necessary formula. 3
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Q. 23. A student has two wires of iron and copper of equal length and diameter. He joins the two wires in series and passes electric current through the combination which increases gradually. After that he joins the two wires in parallel and repeats the process of passing current Which wire will glow first in each case and why ?
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Q. 24. A sunshine recorder globe of 30 cm diameter is made of glass of refractive index µA. = 1-5. A ray enters the globe parallel to the axis. Find the position from the centre of the sphere when the ray crosses the axis.
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Q. 25. Differentiate between N-type and P-type semiconductors on the basis of energy band diagrams. Explain the process of conduction in both type of materials. 3
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Q. 26. The frequency of a cyclotron oscillator is 107 Hz. What should be the operating magnetic field for accelerating protons ? If the radius of the dee’s of the cyclotrons is 6 X 10-1 m, calculate the energy of the proton beam produced by it in MeV. Given e = 1.6 X 10-19 C ; M,, = 1•67,. x 10-27 kg; 1 MeV = 1.602 x 10-13J.
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Q. 27. A narrow monochromatic beam of light of intensity 1 is incident on a glass plate.
Another identical glass plate is kept close to the first one and parallel to it. Each plate reflects 25%
of the incident light and transmits the remaining. Calculate the ratio of minimum and the maximum
intensity in the interference pattern formed by two beams obtained after reflection from each plate. 3
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Q. 28. With the help of a labelled diagram, explain the principle, construction and working of an A.C. generator.
Alternative Question
With the help of a labelled diagram, explain the principle, construction and working of a step up transformer. Why is the core laminated ?
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Q. 29. A glass rod rubbed with silk is brought close to two uncharged spheres in contact with each other inducing charges on them as shown in figure. Show with diagram in each case, what happens when
(i) the spheres are slightly separated, (ii) the spheres are subsequently removed. (iii) the spheres are separated far apart.
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Q. 30. A photon of wavelength 3310 A falls on a photocathode and an electron of energy 3 X 10-19 J is ejected. If the wavelength of the photon is charged to 5000 A, the energy of the ejected electron is 7.91 X 10-20 J, calculate the value of Planck’s constant and threshold wavelength of photon.
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