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Assertion: A wire carrying an electrical current has no electric field inside it. Reason: Rate of flow of electrons in one direction is equal to the rate of flow of protons in opposite

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Assertion: The drift velocity of electrons in a metallic wire decreases, when temperature of the wire increases. Reason: On increasing temperature, conductivity of metallic wire

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Two toroids 1 and 2 have total number of turns 200 and 100 respectively with average radii 40 cm and 20 cm, respectively. If they carry same current `i`, the ratio of the magnetic fields along the two loops

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Two magnets have the same length and the same pole strength. But one of the magnets has a small hole at its centre.

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Assertion: If a straight wire is moved in a magnetic field, no emf will be induced across its two ends as the circuit is not closed. Reason: Since, the circuit is not closed, induced current will be

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The selectivity of a series L-C-R `AC` circuit is large,

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Assertion: When the capacitor is connected to an AC source, it limits or regulates the current, but does not completely prevent the flow of charge. Reason: The capacitor is alternately charged and discharged as the current reverses each

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A screen is placed 90cm from an object. The image of the object on the screen is formed by a convex lens at two different locations separated by 20cm. Determine the focal length of the

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You are given prisms made of crown glass and flint glass with a wide variety of angles. Suggest a combination of prisms which will disperse (and displace) a pencil of white light without much

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When monochromatic light travels from one medium to another, its wavelength changes but frequency remains the same.

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Write the conditions for observing a rainbow. Show by drawing suitable diagram how one understands the formation of a

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Define power of a lens. Write its units. Deduce the relation `1/f=1/f_1+1/f_2` for two thin lenses kept in contact

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Consider a thin lens placed between a source (S) and an observer (O) (Fig.). Let the thickness of the lens vary as `w(b)=w_0-b^2/a`, where b is the verticle distance from the pole. w0 is a constant. Using Fermat’s principle i.e. the time of transit for a ray between

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In a Young’s double-slit experiment, the slits are separated by 0.28 mm and the screen is placed 1.4 m away. The distance between the central bright fringe and the fourth bright fringe is measured to be 1.2 cm. Determine the wavelength of light used in the

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Two towers on top of two hills are 40 km apart. The line joining them passes 50 m above a hill halfway between the towers. What is the longest wavelength of radio waves, which can be sent between the towers without appreciable diffraction

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In deriving the single slit diffraction pattern, it was stated that the intensity is zero at angles of nλ/a. Justify this by suitably dividing the slit to bring out the

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Consider sunlight incident on a pinhole of width 103A. The image of the pinhole seen on a screen shall

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From your answer to (i), guess what order of accelerating voltage (for electrons) is required in such a tube

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Answer the following questions: Quarks inside protons and neutrons are thought to carry fractional charges [(+2/3)e ; (–1/3)e]. Why do they not show up in Millikan’s oil-drop

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Consider Fig. Suppose the voltage applied to A is increased. The diffracted beam will have the maximum at a value of θ that

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