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The distance between the plates of a parallel plate capacitor is d. A metal plate of thickness (d/2) is placed between the plates. What will be the effect on the

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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A point charge +10 µC is a distance 5 cm directly above the centre of a square of side 10 cm, as shown in Fig. . What is the magnitude of the electric flux through the square? (Hint: Think of the square as one face of a cube with edge 10

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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Why does the electric field inside a dielectric decrease when it is placed in an external electric

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Let `P(r) = Q/(πR^4)r` be the charge density distribution for a solid sphere of radius R and total charge Q. For a point ‘P’ inside the sphere at distance `r_1` from the centre of the sphere the magnitude of electric field

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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A paisa coin is made up of Al−Mg alloy and weighs 0.75g. It has a square shape and its diagonal measures 17mm. It is electrically neutral and contains equal amounts of positive and negative charges. Treating the paisa coins made up of only Al, find the magnitude of an equal number of positive and negative

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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A metal rod of length 2 m rotates vertically about one of its end with frequency 2 Hz. The horizontal component of earth's magnetic field is `3.14xx 10^(-5)` then emf developed between two ends of road

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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Assertion: At macroscopic level, quantisation of charge has no practical consequence and can be ignored. Reason: `1 muC` charge contains `10^(15)` times electronic charge e

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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Assertion: Upon displacement of charges within a closed surface, E at any point on the surface does change. Reason: The flux crossing through a closed surface is dependent on the location of charge within the

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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To ensure almost 100 per cent transmittivity, photographic lenses are often coated with a thin layer of dielectric material. The refractive index of this material is intermediated between that of air and glass (which makes the optical element of the lens). A typically used dielectric film is MgF2 (n = 1.38). What should the thickness of the film be so that at the center of the visible speetrum (5500 A o ) there is maximum transmission.

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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(i) Explain the meaning of the statement ‘electric charge of a body is quantised’.(ii) Why can one ignore quantisation of electric charge when dealing with macroscopic i.e., large scale

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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Consider a closed loop C in a magnetic field (Fig ). The flux passing through the loop is defined by choosing a surface whose edge coincides with the loop and using the formula φ = B1.dA1 + B2.dA2 + ... . Now if we chose two different surfaces S1 and S2 having C as their edge, would we get the same answer for flux. Jusity your

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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In the LCR circuit shown in Fig , the ac driving voltage is `v = V_m sin ωt`. Describe subsequent motion of

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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A monoenergetic (18 keV) electron beam initially in the horizontal direction is subjected to a horizontal magnetic field of 0.04 G normal to the initial direction. Estimate the up or down deflection of the beam over a distance of 30 cm (me = 9.11 × 10 –31 kg). [Note: Data in this exercise are so chosen that the answer will give you an idea of the effect of earth’s magnetic field on the motion of the electron beam from the electron gun to the screen in a TV

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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EMF of a CellAn electric cell is a source of energy that maintains a continuous flow of charge in a circuit. It changes chemical energy into electrical energy. It has two electrodes, positive electrode and negative electrode as shown below.Electric cell has to do some work in maintaining the current through a circuit. The work done by the cell in moving unit positive charge through the whole circuit (including the cell) is called the electromotive force (emf) of the cell. For the given circuit, if the cell has an emf of `2 V` and the internal resistance of this cell

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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The optical properties of a medium are governed by the relative permitivity (`ε_r`) and relative permeability (`μ_r` ). The refractive index is defined as `sqrt(μ_rε_r) = n` .For ordinary material `ε_r` > 0 and `μ_r` > 0 and the positive sign is taken for the square root. In 1964, a Russian scientist V. Veselago postulated the existence of material with `ε_r` < 0 and `μ_r` < 0. Since then such ‘metamaterials’ have been produced in the laboratories and their optical properties studied. For such materials `n = -sqrt(μ εr r)` . As light enters a medium of such refractive

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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A polythene piece rubbed with wool is found to have a negative charge

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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Resistance and Resistivity The materials can be classified as conductors, semiconductors and insulators depending on their resistivities, in an increasing order of their values. Metals have low resistivities in the range of `10^(-8)Omegam` to `10^(-6)Omegam`. At the other end are insulators like ceramic, rubber and plastics having resistivities `10^(18)` times greater than metals or more. In between these two are the semiconductors. These however, have resistivities characteristically decreasing with a rise in temperature. The resistivities of semiconductors can be decreased by adding small amount of suitable impurities. This last feature is exploited in use of semiconductors for electronic devices.Commercially produced

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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An infinitely long cylinder of radius R is made of an unusual exotic material with refractive index –1 (Fig). The cylinder is placed between two planes whose normals are along the y direction. The center of the cylinder O lies along the y-axis. A narrow laser beam is directed along the y direction from the lower plate. The laser source is at a horizontal distance x from the diameter in the y direction. Find the range of x such that light emitted from the lower plane does not reach the upper

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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Figure shows two charges of equal magnitude separated by a distance 2a. As we move away from the charge situated at x = 0 to the charge situated at `x=2a`, which of the following graphs shows the correct behaviour of electric field

asked Mar 20, 2022 in 12th Physics by varun (6.7k points)

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The Sun’s angular diameter is measured to be 1920′′. The distance D of the Sun from the Earth is `1.496 xx 10^11` m. What is the diameter of the Sun

asked Mar 19, 2022 in 11th Physics by varun (6.7k points)

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