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The efficiency of an ideal heat engine working between the freezing point and boiling point of water, is
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A carbon resistor of (47 ± 4.7) kΩ is to be marked with rings of different colours for its identification. The colour code sequence will be
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A set of n equal resistors, of value R each, are connected in series to a battery of emf E and internal resistance R. The current drawn is I. Now, the n resistors are connected in parallel to the same battery. Then the current drawn from battery becomes 10 I. The value of n is
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A battery consists of a variable number n of identical cells (having internal resistance r each) which are connected in series. The terminals of the battery are short-circuited and the current I is measured. Which of the graphs shows the correct relationship between I and n?
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Unpolarised light is incident from air on a plane surface of a material of refractive index $\mu$. At a particular angle of incidence i, it is found that the reflected and refracted rays are perpendicular to each other. Which of the following options is correct for this situation?
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In Youngs double slit experiment the separation d between the slits is 2 mm, the wavelength $\lambda$ of the light used is 5896 Å and distance D between the screen and slits is 100 cm. It is found that the angular width of the fringes is 0.20°. To increase the fringe angular width to 0.21° (with same $\lambda$ and D) the separation between the slits needs to be changed to
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An astronomical refracting telescope will have large angular magnification and high angular resolution, when it has an objective lens of
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The ratio of kinetic energy to the total energy of an electron in a Bohr orbit of the hydrogen atom, is
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An electron of mass m with an initial velocity $\overrightarrow{V}= V_{o}\hat{i}\left(V_{o}>0\right)$ enters an electric field $\overrightarrow{E}= -E_{o}\hat{i}\left(E_{o}= constant >0 \right)$ at t=0 . If $\lambda_{o}$ is its de-Broglie wavelength initially, then its de-Broglie wavelength at time t is
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For a radioactive material, half-life is 10 minutes. If initially there are 600 number of nuclei, the time taken (in minutes) for the disintegration of 450 nuclei is
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