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(i) A plane wavefront approaches a plane surface separating two media. If medium 1 is optically denser and medium 2 is optically rarer, using Huygens' principle, explain and show how a refracted wavefront is ^constructed?(ii) Verify Snell's law.(iii) When a light wave travels from a rarer to a denser medium, the speed decreases. Does it imply reduction in its energy?

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

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(i) Consider two coherent sources `S_1 and S_2` producing monochromatic waves to produce interference pattern. Let, the displacement of the wave produced by `S_1` be given by `Y_1 = acosomegat` and the displacement by `S_2` be `Y_2 = acos(omegat +phi)` Find out the expression for the amplitude of the resultant displacement at a point and show that the intensity at that point will be `I = 4a^2 cos^2phi/2` Hence, establish the conditions for constructive and destructive interference.(ii) What is the effect on the interference fringes in Young's double slit experiment when (i) the width of the source slit is increased;

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

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Find the(i) maximum frequency,(ii) minimum wavelength of X-rays produced by 30 kV

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

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A 100W sodium lamp radiates energy uniformly in all directions. The lamp is located at the centre of a large sphere that absorbs all the sodium light which is incident on it. The wavelength of the sodium light is 589 nm. At what rate are the photons delivered to

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

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Consider a thin target (10–2m square, 10–3m thickness) of sodium, which produces a photocurrent of 100μA when a light of intensity 100W/m2 (λ = 660nm) falls on it. Find the probability that a photoelectron is produced when a photons strikes a sodium atom. [Take density of Na = 0.97

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

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Consider a 20 W bulb emitting light of wavelength 5000 A ° and shining on a metal surface kept at a distance 2m. Assume that the metal surface has work function of 2 eV and that each atom on the metal surface can be treated as a circular disk of radius 1.5 A ° .

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

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Consider a 20 W bulb emitting light of wavelength 5000 A ° and shining on a metal surface kept at a distance 2m. Assume that the metal surface has work function of 2 eV and that each atom on the metal surface can be treated as a circular disk of radius 1.5 A ° .

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

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Draw a graph showing the variation of stopping potential with frequency of the incident radiations. What does the slope of the line with the frequency axis indicate. Hence define threshold

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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A surface has the area vector `vecA= (2hati + 3hatj)m^2`. The flux of an electric field through itifthe field is `vecE=-4hati V/m`

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

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A square surface of side L metres is in the plane of uur the paper. A uniform electric field `vecE ('volt' /m)`, also in the plane of the paper, is limited only to the lower half of the square surface (see figure). The electric flux in SI units associated with the surface is

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

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If a point charge q is placed at the centre of a cube. What is the flux linked (a) with the cube? (b) with each face of the

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

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Two conducting plates A and B are placed parallel to each other. A is given a charge `Q_1 and B` a charge `Q_2` . Prove that the charges on the inner facing surfaces are of equal magnitude and opposite sign. Also find the charges on inner & outer

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

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Uniform electric field of magnitude 100 V/m in space is directed along the line `y= 3 + x`. Find the potential difference between point `A (3, 1) & B

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

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Two point masses m each carrying charge –q and +q are attached to the ends of a massless rigid non-conducting rod of length l. The arrangement is placed in a uniform electric field E such that the rod makes a small angle `5^0` with the field direction. The minimum time needed by the rod to align itself along the field is

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

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A n electric dipole is placed at an angle of 60o with an electric field of intensity `10^5 NC^(–1)` . It experiences a torque equal to `8 sqrt3Nm` . If the dipole length is 2cm then the charge on the dipole is ...........

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

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A Charge q is placed at the centre of the open end of cylindrical vessel. The flux of theelectric field through the surface of the vessel is

asked Mar 20, 2022 in 12th 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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State the law of equi-partition of

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

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A body describes simple harmonic motion with an amplitude of 5 cm and a period of 0.2 s. Find the acceleration and velocity of the body when the displacement is (a) 5 cm (b) 3 cm (c) 0

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

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