1
JEE Main 2017 (Offline)
+4
-1
A magnetic needle of magnetic moment 6.7 $$\times$$ 10-2 A m2 and moment of inertia 7.5 $$\times$$ 10-6 kg m2 is performing simple harmonic oscillations in a magnetic field of 0.01 T. Time taken for 10 complete oscillations is:
A
8.76 s
B
6.65 s
C
8.89 s
D
6.98 s
2
JEE Main 2017 (Offline)
+4
-1
When a current of 5 mA is passed through a galvanometer having a coil of resistance 15$$\Omega$$, it shows full scale deflection. The value of the resistance to be put in series with the galvanometer to convert it into a voltmeter of range 0 – 10V is:
A
4.005 × 103 $$\Omega$$
B
1.985 × 103 $$\Omega$$
C
2.535 × 103 $$\Omega$$
D
2.045 × 103 $$\Omega$$
3
JEE Main 2016 (Online) 10th April Morning Slot
+4
-1
A fighter plane of length 20 m, wing span (distance from tip of one wing to the tip of the other wing) of 15 m and height 5 m is flying towards east over Delhi. Its speed is 240 ms−1. The earth’s magnetic field over Delhi is 5 $$\times$$10−5 T with the declination angle ~ 08 and dip of $$\theta$$ such that sin $$\theta$$ = 2 3 . If the voltage developed is VB between the lower and upper side of the plane and VW between the tips of the wings then VB and VW are close to :
A
VB = 45 mV; VW = 120 mV with right side of pilot at higher voltage
B
VB = 45 mV; VW = 120 mV with left side of pilot at higher voltage
C
VB = 40 mV; VW = 135 mV with right side of pilot at high voltage
D
VB = 40 mV; VW = 135 mV with left side of pilot at higher voltage
4
JEE Main 2016 (Online) 10th April Morning Slot
+4
-1
Consider a thin metallic sheet perpendicular to the plane of the paper moving with speed ‘v’ in a uniform magnetic field B going into the plane of the paper (See figure). If charge densities $$\sigma$$1 and $$\sigma$$2 are induced on the left and right surfaces, respectively, of the sheet then (ignore fringe effects) :

A
$$\sigma$$1 = $$\in$$0 $$\upsilon$$ B, $$\sigma$$2 = $$-$$ $$\in$$0 $$\upsilon$$ B
B
$$\sigma$$1 = $${{{ \in _0}\upsilon \,B} \over 2},$$ $$\sigma$$2 = $${{ - { \in _0}\,\upsilon B} \over 2}$$
C
$$\sigma$$1 = $$\sigma$$2 = $${ \in _0}\,\upsilon B$$
D
$$\sigma$$1 = $${{ - { \in _0}\upsilon B} \over 2},$$ $$\sigma$$2 = $${{ { \in _0}\upsilon B} \over 2},$$
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