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Obtain the expression for the maximum kinetic energy of the electrons emitted from a metal surface in terms of the frequency of the incident radiation and the threshold

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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

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A free proton and a free electron are placed in a uniform field. Which of the two experience greater force and greater

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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 .....

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How many protons are there in

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1MW power is to be delivered from a power station to a town 10 km away. One uses a pair of Cu wires of radius 0.5 cm for this purpose. Calculate the fraction of ohmic losses to power transmitted if a step-up transformer is used to boost the voltage

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

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As shown in figure after a long time the battery is disconnected and short circuiting the points A & B. The current in circuit after 2ms after the short circuit

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

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In the transmission of a.c. power through transmission lines, when the voltage is shapped up n times, the power loss in

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In the circuit shown in figure `E=25V, L=2H, C=60 muF, R_1 = 5Omega and R_2=10Omega`. Switch S is closed at `t = 0.` Column-I Column-II (A) Current through `R_1` at t = 0 (P) 0 (B) Current through `R_2` at t = 0 (Q) 5A (C) Current through `R_1` at `t =oo` (R) 2.5 A (D) Current through `R_2` at `t =oo` (S) 7.5 A (T) None of these

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If magnetic monopoles existed, how would the Gauss’s law of magnetism be

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Self-Induction Self-induction is the property of a coil by virtue of which the coil opposes any change in the strength of current flowing through it by inducing an emf in itself. This induced emf is also called back emf. When the current in a coil is switched ON, then the self induction opposes the growth of the current and when it is switch OFF, then the self-induction opposes the decay of the current.The inductance that would be needed to store 1 kWh of energy in a coil carrying a 200 A current

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

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The Transformer Transformer is a device, which is used to increase or decrease the alternating voltage. The transformers are of the following types (i) Step-up transformer (ii) Step-down transformerTransformer is based upon the principle of mutual induction. It consists of two coils, primary coil `(p)` and secondary coil `(s)`, insulated from each other wounded on soft iron core.Often the primary coil is the input coil and secondary coil is the output coil. These soft iron cores are laminated to minimise eddy current loss.Which quantities do not change during transformer

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

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A mobile phone lies along the principal axis of a concave mirror, as shown in Fig. . Show by suitable diagram, the formation of its image. Explain why the magnification is not uniform. Will the distortion of image depend on the location of the phone with respect to the

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What focal length should the reading spectacles have for a person for whom the least distance of distinct vision is 50

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Explain with the help of a ray diagram, the working of an astronomical telescope. The magnifying power of a telescope in its normal adjustment is 20. If the length of the telescope is 105 cm in this adjustment, find the focal lengths of the two

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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State the importance of coherent sources in the phenomenon of interference. In Young's double slit experiment to produce interference pattern, obtain the conditions for constructive and destructive interference. Hence, deduce the expression for the fringe width. How does the fringe width get affected, if the entire experimental apparatus of YDSE is immersed in

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State briefly two features which can distinguish the characteristic features of an interference pattern from those observed in the diffraction pattern due to a single

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The work function for the following metals is given: Na: 2.75 eV; K: 2.30 eV; Mo: 4.17 eV; Ni: 5.15 eV. Which of these metals will not give photoelectric emission for a radiation of wavelength 3300 Å from a He-Cd laser placed 1 m away from the photocell? What happens if the laser is brought nearer and placed 50 cm away

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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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