Two small balls each carrying a charge q and mass m are attached to the ends of a light rod of length d which is suspended from the ceiling by a thin tension free fiber as shown in the figure. There is a uniform magnetic B pointing straight down, in the cylindrical region of radius R around the fiber. The system is initially at rest. If the magnetic field is turned off, which of the following describes what happens to the system immediately?
A)
It rotates with angular momentum \[qB{{R}^{2}}\]
doneclear
B)
It rotates with angular momentum \[\frac{qB{{d}^{2}}}{4}\]
doneclear
C)
It rotates with angular velocity \[\frac{qB{{R}^{2}}}{m{{d}^{2}}}\]
doneclear
D)
It rotates with angular velocity \[\frac{qB}{2m}\]
In the figure shown XX represents a vertical plane perpendicular to the plane of the figure. To the right of this plane there is a uniform horizontal magnetic field B directed into the plane of the figure. A uniform electric field E exists horizontally perpendicular to the magnetic field in entire space. A charge particle having charge q and mass m is projected vertically upward from point 0. It crosses the plane XX after time T. Find the speed of projection of the particle if it was observed to move uniformly after time T. It is given that\[qE=mg\].
A large transparent cube (refractive index\[=1.5\]) has a small air bubble inside it. When a coin (diameter\[2\text{ }cm\]) is placed symmetrically above the bubble on the top surface of the cube, the bubble cannot be seen by looking down into the cube at any angle. However, when a smaller coin (diameter\[1.5cm\]) is placed directly over it, the bubble can be seen by looking down into the cube. What is the range of the possible depths d of the air bubble beneath the top surface?
Four point charges q, q, q and \[-q\]are placed at the vertices of a square of side length a. The configuration is changed and the charge are positioned at the vertices of a rhombus of side length a with \[-q\] charge at the vertex where angle is\[120{}^\circ \]. Find the work done by the external agent in changing the configuration.
Seven identical plates, each of area A, are placed as shown. Any two adjacent plates are at separation d. Conducting wires have been used to connect the plates and a cell of emf V volt as shown in the figure. How much charge does the cell supply?
In Young's double-slit experiment, the separation between two slits is \[d=0.32\text{ }mm\]and the wavelength of light used is\[\lambda =5000\text{ }\overset{o}{\mathop{A}}\,\]. Find the number of maxima in the angular range\[-{{\sin }^{-1}}(0.6)\le \theta \le {{\sin }^{-1}}(0.6)\].
The resistance between P and S in shown circuit is of \[300\,\Omega ,\] which is tapped at Q and R such that\[PQ=QR=RS\]. If the potential difference between A and B is \[320\text{ }V,\] the potential difference between R and S is \[2\times {{10}^{N}}V.\] Find the value of N.
Convex surface of thin concavo-convex lens of refractive index \[1.5\] is silvered as shown. A small object is kept in air at 30 cm left of the lens on its principal axis. What is the distance (in cm) of the final image from mirror?
In the circuit shown in figure AB is a uniform wire of length\[L=5\text{ }m\]. It has a resistance of\[2\Omega /m\]. When \[AC=2.0\text{ }m,\]it was found that the galvanometer shows zero reading when switch S is placed in either of the two positions 1 or 2. Find the emf \[{{E}_{1}}\](in V)
[A] In the Aluminothermite process, aluminium acts as reducing agent.
[B] The process of extraction of gold involves the formation of \[{{[Au{{(CN)}_{2}}]}^{-}}\] and \[{{[Zn{{(CN)}_{4}}]}^{2-}}\].
[C] In the extractive metallurgy of zinc, partial fusion of \[ZnO\]with coke is called sintering and reduction of ore to the molten metal is called smelting.
[D] Extractive metallurgy of silver from its ore argentite involves complex formation and displacement by more electropositive metal.