1
JEE Main 2013 (Offline)
+4
-1
A metallic rod of length $$'\ell '$$ is tied to a string of length $$2$$$$\ell$$ and made to rotate with angular speed $$w$$ on a horizontal table with one end of the string fixed. If there is a vertical magnetic field $$'B'$$ in the region, the $$e.m.f$$ induced across the ends of the rod is
A
$${{2B\omega \ell } \over 2}$$
B
$${{3B\omega \ell } \over 2}$$
C
$${{4B\omega {\ell ^2}} \over 2}$$
D
$${{5B\omega {\ell ^2}} \over 2}$$
2
AIEEE 2012
+4
-1
A coil is suspended in a uniform magnetic field, with the plane of the coil parallel to the magnetic lines of force. When a current is passed through the coil it starts oscillating; It is very difficult to stop. But if an aluminium plate is placed near to the coil, it stops. This is due to :
A
development of air current when the plate is placed
B
induction of electrical charge on the plate
C
shielding of magnetic lines of force as aluminium is a para-magnetic material.
D
electromagnetic induction in the aluminium plate giving rise to electromagnetic damping.
3
AIEEE 2011
+4
-1
A boat is moving due east in a region where the earth's magnetic fields is $$5.0 \times {10^{ - 5}}$$ $$N{A^{ - 1}}\,{m^{ - 1}}$$ due north and horizontal. The best carries a vertical aerial $$2$$ $$m$$ long. If the speed of the boat is $$1.50\,m{s^{ - 1}},$$ the magnitude of the induced $$emf$$ in the wire of aerial is :
A
$$0.75$$ $$mV$$
B
$$0.50$$ $$mV$$
C
$$0.15$$ $$mV$$
D
$$1$$ $$mV$$
4
AIEEE 2010
+4
-1
A rectangular loop has a sliding connector $$PQ$$ of length $$l$$ and resistance $$R$$ $$\Omega$$ and it is moving with a speed $$v$$ as shown. The set-up is placed in a uniform magnetic field going into the plane of the paper. The three currents $${I_1},{I_2}$$ and $$I$$ are
A
$${I_1} = - {I_2} = {{Blv} \over {6R}},\,\,I = {{2Blv} \over {6R}}$$
B
$${I_1} = {I_2} = {{Blv} \over {3R}},\,\,I = {{2Blv} \over {3R}}$$
C
$${I_1} = {I_2} = I = {{Blv} \over R}$$
D
$${I_1} = {I_2} = {{Blv} \over {6R}},I = {{Blv} \over {3R}}$$
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