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For a normal eye, the far point is at infinity and the near point of distinct vision is about 25cm in front of the eye. The cornea of the eye provides a converging power of about 40 dioptres, and the least converging power of the eye-lens behind the cornea is about 20 dioptres. From this rough data estimate the range of accommodation (i.e., the range of converging power of the eye-lens) of a normal

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

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Trace the rays of light showing the formation of an image due to a point object placed on the axis of a spherical surface separating the two media of refractive indices `n_1 and n_2`. Establish the relation between the distance of the object, the distance of image and the radius of curvature from the central point of the spherical surface. Hence, derive the expression of the lens maker's

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

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(i) Estimate the speed with which electrons emitted from a heated emitter of an evacuated tube impinge on the collector maintained at a potential difference of 500 V with respect to the emitter. Ignore the small initial speeds of the electrons. The specific charge of the electron, i.e., its e/m is given to be 1.76 × 1011 C kg–1 .(ii) Use the same formula you employ in (i) to obtain electron speed for an collector potential of 10 MV. Do you see what is wrong ? In what way is the formula to be

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

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An electron has kinetic energy equal to 100eV. Calculate (1) momentum (2) speed (3) Debroglie wavelength of the

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A particle executing SH.M has a maximum displacement of 4 cm and its acceleration at a distance of 1 cm from its mean position is 3 cm/`s^2`. What will be its velocity when it is at a distance of 2cm from its mean

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

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A coil of 0.01 henry inductance and 1 ohm resistance is connected to 200 volt, 50 Hz ac supply. Find the impedance of the circuit and time lag between max. alternating voltage and

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

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Alternating current can not be measured by dc ammeter

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The current in a wire varies with time according to the equation `i=4+ 2t`, where `i` is in ampere and `t` is in second. The quantity of charge which passes through a cross-section of the wire during the time `t= 2 s` to `t = 6 s`

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

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What is the de Broglie wavelength associated with a ball of mass 150 g travelling at 30.0

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

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A sphere of radius `r_1` encloses a change Q. If there is another concentric sphere S2 of radius `r_2 (r_2 > r_1)` and there is no additional change between S1 and S2. Find the ratio of electric flux through S1 and

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

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True or false. Write reasons

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In a region of uniform magnetic induction `B = 10^(-2)` tesla, a circular coil of radius 30 cm and resistance ` π^2` ohm is rotated about an axis which is perpendicular to the direction of B and which forms a diameter of the coil. If the coil rotates at 200 rpm the amplitude of the alternating current induced in the coil

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

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Find out reading of A C ammeter and also calculate the potential difference across, resistance and

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

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According the Gauss’s theorem, electric field of an infinitely long straight wire is inversely proportional to

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

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A ,B and C are three points in a uniform electric field, the electric potential

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

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Electron Moving in Magnetic Field An electron with a speed `v_0 ( < < c)` moves in a circle of radius `r_0`, in a uniform magnetic field. This electron is able to travel in a circular path as magnetic field is perpendicular to the velocity of the electron. The time required for one revolution of the electron is `T_0`. The speed of the electron is now, doubled to `2v_0`.If this electron of charge (e) is moving parallel to uniform magnetic field with constant velocity `v`. The force acting on the electron

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

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A thin convex lens of focal length 25 cm is cut into two pieces 0.5 cm above the principal axis. The top part is placed at (0,0) and an object placed at (–50 cm, 0). Find the coordinates of the

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

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Consider a system of three charges `q/3, q/3 and –2a/3` placed at points A, B and C respectively as shown in the figure. It the radius of the circle is R and `/_CAB = 60^o` then the electric field at centre 0 is ........

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

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An electrostatic field line is a continuous curve. That is, a field line cannot have sudden breaks. Why

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

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Consider a sphere of radius R with charge density distributed as `ρ (r ) = kr ' for ' r le R` `ρ (r ) =0 ' for ' r > R` . (i) Find the electric field at all points r.(ii) Suppose the total charge on the sphere is 2e where e is the electron charge. Where can two protons be embedded such that the force on each of them is zero. Assume that the introduction of the proton does not alter the negative charge

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

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