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Dielectrics Dielectrics are insulating (non-conducting) materials that can produce electric effect without conduction. Movement of free charges is not possible in a dielectric, so they behave differently.When a dielectric material is kept in an electric field, then the external field induces dipole moment. Due to which, net charges on the surface of the dielectric appears.Molecules that has no permanent dipole moments

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The variation between `V -i` for heating filament is shown by which

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A potentiometer circuit is set up as shown. The potential gradient across the potentiometer wire, is `k` volt/cm and the ammeter, present in the circuit, reads `1.0` A when two way key is switched off. The balance points, when the key between the terminals (i) 1 and 2 (ii) 1 and 3, is plugged in, are found to be at lengths `l_1 cm and l_2 cm`, respectively. The magnitudes of the resistors `R and X` in ohm, are then, respectively equal

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Wheatstone Bridge In 1845 by German physicist Gustav Kirchhoff described Kirchhoff’s circuit laws which are two equalities that deal with the current and potential difference (commonly known as voltage) in the lumped element model of electrical circuits.As an application of these laws, consider the circuit shown below, which is called the Wheatstone bridge. This bridge consists of four resistors `R_1, R_2, R_3 and R_4`. Across one pair of diagonally opposite points (A and C in the figure) a source is connected.This (i.e., AC) is called the battery arm. Between the other two vertices, B and Z), a galvanometer G (which

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A long solenoid carrying a current produces a magnetic field B along its axis. If the current is doubled and the number of turns/cm is halved, the new value of the magnetic field

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Lorentz Force and Its Effects A charged particle moving in an external magnetic field experiences a force, which is called Lorentz force, i.e. `F=q(v xx B)`,where `q` is the charge on the particle and v is the velocity of the particle. The direction of the force is given by the cross product of velocity vector and magnetic field vector at any time.The charge particle travels in a special trajectory called helical path. Because the force is always perpendicular to the velocity vector, the magnetic field can do no work on an isolate charge. Hence, the linear velocity always remains the

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Earth’s Magnetic FieldThe magnetic field lines of the earth resemble that of a hypothetical magnetic dipole located at the centre of the earth. The axis of the dipole is presently tilted by approximately 11.3° with respect to the axis of rotation of the earth.The pole near the geographic north pole of the earth is called the north magnetic pole and the pole near the geographic south pole is called south magnetic pole.A bar magnet is placed north-south with its north pole due north. The points of zero magnetic field will be in which direction from centre of

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The North-pole of a magnet is falling on a metallic ring as shown in the figure. The direction of induced current, if looked from upside, in the ring will

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The mutual inductance `M_(12)` of coil 1 with respect to coil

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Assertion: Capacitor serves as a barrier for DC and offers an easy path to AC. Reason: Capacitive reactance is directly proportional to

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The above person prefers to remove his spectacles while reading a book. Explain

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A tank is filled with water to a height of 12.5 cm. The apparent depth of a needle lying at the bottom of the tank is measured by a microscope to be 9.4 cm. What is the refractive index of water? If water is replaced by a liquid of refractive index 1.63 up to the same height, by what distance would the microscope have to be moved to focus on the needle

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A small bulb is placed at the bottom of a tank containing water to a depth of 80cm. What is the area of the surface of water through which light from the bulb can emerge out? Refractive index of water is 1.33. (Consider the bulb to be a point

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A small telescope has an objective lens of focal length 150 cm and eyepiece of focal length 5 cm. What is the magnifying power of the telescope for viewing distance objects in normal adjustments. If this telescope is used to view a 100 m tall tower 3 km away, then what is the height of the tower formed by the objective

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(i) A mobile phone lies along the I principal axis of a concave mirror. Show with the help of a suitable diagram, the formation of its image. Explain whymagnification is not a uniform, (ii) Suppose the lower half of the concave mirror's reflecting surface is covered with an opaque material. What effect this will have on the image of the object?

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A ray of light incident at an angle θ on a refracting face of a prism emerges from the other face normally. If the angle of the prism is 5° and the prism is made of a material of refractive index 1.5, the angle of incidence

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If light passes near a massive object, the gravitational interaction causes a bending of the ray. This can be thought of as happening due to a change in the effective refrative index of the medium given by n(r) = 1 + 2 GM/rc2 where r is the distance of the point of consideration from the centre of the mass of the massive body, G is the universal gravitational constant, M the mass of the body and c the speed of light in vacuum. Considering a spherical object find the deviation of the ray from the original path as it

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What is the effect on the interference fringes in a Young’s double-slit experiment due to: the width of the source slit is

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Is the speed of light in glass independent of the colour of light? If not, which of the two colours red and violet travels slower in a glass

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In Young’s double-slit experiment using monochromatic light of wavelength λ, the intensity of light at a point on the screen where path difference is λ, is K units. What is the intensity of light at a point where path difference is

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

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