A horizontal cesium plate ( = 1.9eV) is moved vertically downward at a constant speed u in a room full of radiation of wavelength 250 run and above. What should be the minimum value of u so that the vertically upward component of velocity is nonpositive for each photoelectron?

When =250nmEnergy of photon = hc =1240 250 =4.96ev .E.= hc -w=4.96-1.9ev. Velocity to be non positive for each photo electron The minimum value of velocity of plate should be = velocity of photo electron Velocity of photo electron = 2KE m = 3.06 9.1 10^ -31 = 3.06 1.6 10^ -19 9.1 10^ -31 =1.04 10^6m/sec.

A horizontal cesium plate ( = 1.9eV) is moved vertically downward…

Consider the arrangement shown in figure. By some mechanism, the separation between the slits $S_3$ and $S_4$ can be changed. The intensity is measured at the point $P$ which is at the common perpendicular bisector

of $S_1,S_2$ and $S_3,S_4$.
When $\text{z}=\frac{\text{D}\lambda}{2\text{d}},$ intensity measured at $P$ is $I$.
Find this intensity when $z$ is equal to:

$\frac{\text{D}\lambda}{\text{d}}$
$\frac{3\text{D}\lambda}{2\text{d}}$
$\frac{2\text{D}\lambda}{\text{d}}$

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Critically analyse bar magnet and solenoid and calculate the value of magnetic field generated on the axial point of the solenoid.

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Two circular coils of radii 5.0cm and 10cm carry equal currents of 21 A. The coils have 50 and 100 turns reepectively and are placed in such a way that their planes as well as the centres coincide. Find the magnitude of the magnetic field B at the common centre of the coils if the currents in the coils are (a) in the same sense (b) in the opposite sense.

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The separation between the plates of a parallel$-$plate capacitor is $0.500\ cm$ and its plate area is $100\ cm^2.$ A $0.400\ cm$ thick metal plate is inserted into the gap with its faces parallel to the plates. Show that the capacitance of the assembly is independent of the position of the metal plate within the gap and find its value.

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A monoenergetic $(18$ ke $V)$ electron beam initially in the horizontal direction is subjected to a horizontal magnetic field of $0.04 G$ normal to the initial direction. Estimate the up or down deflection of the beam over a distance of $30 \ cm (m_e = 9.11 \times 10^{–19} C).$
$[$Note: Data in this exercise are so chosen that the answer will give you an idea of the effect of earth’s magnetic field on the motion of the electron beam from the electron gun to the screen in a $TV$ set.$]$

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Differentiate between self induction and mutual induction with examples.

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The descending pulley shown in figure has a radius $20\ cm$ and moment of inertia $0.20\ kg-m^2.$ The fixed pulley is light and the horizontal plane frictionless. Find the acceleration of the block if its mass is $1.0\ kg.$

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Write the truth table for the circuits given in Fig. 14.48 consisting of NOR gates only. Identify the logic operations (OR, AND, NOT) performed by the two circuits.