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Calculate electric potential at a point P which is at a distance of 9 cm from a point charge of 50 μC.
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The Figure below shows an infinitely long metallic wire YY' which is carrying a current I'.
P is a point at a perpendicular distance r from it.

- What is the direction of magnetic flux density B of the magnetic field at the point P?
- What is the magnitude of magnetic flux density B of the magnetic field at the point P?
- Another metallic wire MN having length l and carrying a current I is now kept at point P. If the two wires are in vacuum and parallel to each other, how much force acts on the wire MN due to the current I' flowing in the wire YY'?
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Radius of the 1st orbit of hydrogen atom is r0. What will be the radius of the 4th orbit?
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During Rutherford’s gold foil experiment, it was observed that most of the α-particles did not deflect. However, some showed a deflection of 180°.
What hypothesis was made to justify the deflection of α-particle by 180°?
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Name a material which is used in making control rods in a nuclear reactor.
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Write one balanced equation to show Emission of `beta^-` (i.e. a negative beta particle)
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In an experiment of the photoelectric effect, the graph of maximum kinetic energy EK of the emitted photoelectrons versus the frequency v of the incident light is a straight line AB shown in Figure 6 below:

Find:
1) Threshold frequency of the metal
2) The work function of the metal.
3) Stopping potential for the photoelectrons emitted by the light of frequency `v = 30 xx 10^14 Hz`
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With the help of a suitable example and an equation, explain the term pair production.
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Calculate the momentum of a photon of energy 6 x I 0-19 J.
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With reference to the photoelectric effect, what is meant by threshold wavelength?
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Two metals A and B have work functions 4 eV and 6 eV respectively. Which metal has a lower threshold wavelength for photoelectric effect?
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Plot a labelled graph of IVsl where Vs is stopping potential versus frequency f of the incident radiation.
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State how will you use this graph to detennine the value of Planck's constant.
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If the frequency of the incident radiation is increased from 4 × 1015 Hz to 8 × 1015 Hz, by how much will the stopping potential for a given photosensitive surface go up?
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The atomic mass of Uranium `""_92^238"U"` is 238.0508 u, while that of Thorium `""_90^234"Th"` is 234.0436u, and that of Helium `""_2^4"He"` "is 4.0026u. Alpha decay converts `""_92^238"U"` into `""_92^234"Th"` as, shown below:
`""_92^238"U" -> ( ""_90^234"Th" + ""_2^4"He" + "Energy" )`
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Light of wavelength 4000 Å is incident on two metals A and B. Which metal will emit photoelectrons, if their work functions are 3.8 e V and 1.6 e V respectively?
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What conclusion is drawn from Rutherford’s scattering experiment of α-particles?
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Derive the law of reflection using Huygen’s Wave Theory.
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