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(a) What is an equi-potential surface? Show that the electric field is always directed perpendicular to an equi-potential surface. (b) Derive an expression for the potential at a point along the axial line of a short electric

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

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(a) Define dielectric constant in terms of the capacitance of a capacitor? On what factor does the capacitance of a parallel plate capacitor with dielectric depend?(b) Find the ratio of the potential differences that must be applied across the(1) parallel(2) Series combination of two identical capacitors so that the energy stored in the two cases becomes the

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

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Derive an expression for the total work done in rotating an electric dipole through an angle θ in a uniform electric

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What is the speed of ball when rod becomes vertical? A thin homogeneous rod of mass m and length `l` is free to rotate in vertical plane about a horizontal axle pivoted at one end of the rod. A small ball of mass m and charge q is attached to the opposite end of this rod. The whole system is positioned in a constant horizontal electric field of magnitude mg `E=(mg)/(2q)`. The rod is released from shown position from

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

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Two point charges repel each other with a force of 100 N. One of the charges is increased by 10% and other is reduced by 10%. The new force of repulsion at the same distance would be ........

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

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Three identical spheres each having a charge q and radius R, are kept in such a way thateach touches the other two spheares. The magnitude of the electric force on any spheredue to other two is

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

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The principle of ‘parallax’ in section 2.3.1 is used in the determination of distances of very distant stars. The baseline AB is the line joining the Earth’s two locations six months apart in its orbit around the Sun. That is, the baseline is about the diameter of the Earth’s orbit `≈ 3 xx 10^(11)`m. However, even the nearest stars are so distant that with such a long baseline, they show parallax only of the order of 1” (second) of arc or so. A parsec is a convenient unit of length on the astronomical scale. It is the distance of an

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

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A LASER is a source of very intense, monochromatic, and unidirectional beam of light. These properties of a laser light can be exploited to measure long distances. The distance of the Moon from the Earth has been already determined very precisely using a laser as a source of light. A laser light beamed at the Moon takes 2.56 s to return after reflection at the Moon’s surface. How much is the radius of the lunar orbit around the Earth

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

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Two narrow bores of diameters 3.0 mm and 6.0 mm are joined together to form a U-tube open at both ends. If the U-tube contains water, what is the difference in its levels in the two limbs of the tube ? Surface tension of water at the temperature of the experiment is `7.3 × 10^(–2)` N `m^(–1)`. Take the angle of contact to be zero and density of water to be `1.0 × 10^3` kg `m^(–3)` (g = 9.8 m

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

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Which among the curves shown in Fig. cannot possibly represent electrostatic field lines?

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

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Two charges q and –3q are placed fixed on x-axis separated by distance ‘d’. Where should a third charge 2q be placed such that it will not experience any

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

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There are two coils A and B seperated by some distance. If a current of 2 A flows through A, a magnetic flux of 10-2 Wb passes through B (no current through B). If no current passes through A and a current of 1 A passes through B, what is the flux through

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Both alternating current and direct current are measured in amperes. But how is the ampere defined for an alternating

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An ideal transformer has 1:25 turn ratio. The peak value of the ac is 28 V. The rms ms secondary voltage is nearest

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

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A 20 volts ac is applied to a circuit consisting of a resistance and a coil with negligible resistance. If the voltage across the resistance is 12 V, the voltage across the coil

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

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A horizontal overhead power line carries a current of 90 A in east to west direction. What is the magnitude and direction of the magnetic field due to the current 1.5 m below the

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

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The wires which connect the battery of an automobile to its starting motor carry a current of 300 A (for a short time). What is the force per unit length between the wires if they are 70 cm long and 1.5 cm apart? Is the force attractive or

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

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A solenoid has a core of a material with relative permeability 400. The windings of the solenoid are insulated from the core and carry a current of 2A. If the number of turns is 1000 per metre, calculate(i) H,(ii) M,(iii) B (iv) the magnetising current Im

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

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Answer the following questions regarding earth’s magnetism: A vector needs three quantities for its specification. Name the three independent quantities conventionally used to specify the earth’s magnetic

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

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Answer the following questions: The earth may have even reversed the direction of its field several times during its history of 4 to 5 billion years. How can geologists know about the earth’s field in such distant

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

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