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If this telescope is used to view the moon, what is the diameter of the image of the moon formed by the objective lens? The diameter of the moon is 3.48 × 106m, and the radius of lunar orbit is 3.8 ×

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

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A convex lens of focal length 20 cm is placed coaxially with a concave mirror of focal length 10 cm at a distance of 50 cm apart from each other. A beam of light coming parallel to the principal axis is incident on the convex lens. Find the position of the final image formed by this combination. Draw the ray diagram showing the formation of the

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

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A myopic adult has a far point at 0.1 m. His power of accomodation is 4 diopters. What is his near point with glasses? (Take the image distance from the lens of the eye to the retina to be 2

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

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Photoelectrons are emitted with a maximum speed of `7×10^5m`/`s` from a surface when light of frequency `8×10^(14)Hz` is incident on it. Find the threshold frequency for this

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

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An α − particle and a proton are accelerated from rest through same potential difference V. find the ratio of de–broglie wavelength associated with

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

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Two point charges +q and +9q are separated by a distance of 10 a. Find the point on the line joining the two changes where electric field is

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

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Prove that the energy stored in a parallel plate capaSScitor is given by ½ `CV^2`

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

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In a uniformly charged sphere of total charge Q and radius R, the electric field E is plotted as function of distance from the centre. The graph which would correspond to the above will

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

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A thin semi-circular ring of radius r has a positive charge q distributed uniformly overit. The net electric field `vecE` at the centre O

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

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When a Piece of Polythene is rubbed with wool, a charge of `–2xx 10^(-7)` is developed on polythene. The mass transferred to polythene is .....

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

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A hollow cylinder has a charge q coulomb within it. If `phi` is the electric flux in units of voltmeter associated with the curved surface B, the flux linked with the plane surface A in units of volt-meter will be

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

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A non-uniform bar of weight W is suspended at rest by two strings of negligible weight as shown in Fig.. The angles made by the strings with the vertical are 36.9° and 53.1° respectively. The bar is 2 m long. Calculate the distance d of the centre of gravity of the bar from its left end.

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

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Explain why two field lines never cross each other at any

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

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A point charge causes an electric flux of –1.0 × 103 `Nm^2` /C to pass through a spherical Gaussian surface of 10.0 cm radius centred on the charge. If the radius of the Gaussian surface were doubled, how much flux would pass through the

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

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A metallic ring of mass m and radius l (ring being horizontal) is falling under gravity in a region having a magnetic field. If z is the vertical direction, the z-component of magnetic field is `B_z = B_o (1+λ z)`. If R is the resistance of the ring and if the ring falls with a velocity v, find the energy lost in the resistance. If the ring has reached a constant velocity, use the conservation of energy to determine v in terms of m, B, λ and acceleration due to gravity

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

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If a current I given by `I_O sin(omegat-pi/ 2)` flows in an ac circuit across which an ac potential of `E = E_O sinomegat` has been applied, then the power consumption p in the circuit will

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

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A closely wound solenoid of 800 turns and area of cross section 2.5 × 10–4 m2 carries a current of 3.0 A. Explain the sense in which the solenoid acts like a bar magnet. What is its associated magnetic

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

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At a certain location in Africa, a compass points 12° west of the geographic north. The north tip of the magnetic needle of a dip circle placed in the plane of magnetic meridian points 60° above the horizontal. The horizontal component of the earth’s field is measured to be 0.16 G. Specify the direction and magnitude of the earth’s field at the

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

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If the bar magnet in exercise 13 is turned around by 180°, where will the new null points be

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

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At a distance of 10 cm from a long straight wire carrying current, the magnetic field is `4xx10^(-2)` . At the distance of 40 cm, the magnetic field will be

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

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