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JEE 2020 Physics: Bar Magnet & Earth's Magnetism Quiz (02.09.2019)

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Question 1

The earth’s magnetic field lines resemble that of a dipole at the center of the earth. If the magnetic moment of this dipole is close to

the value of earth’s magnetic field near the equator is close to (radius of the earth

)

Question 2

A point charge Q( = 3X10^-12C) rotates uniformly in a vertical circle of radius R=1mm. The axis of the circle is aligned along the magnetic axis of the earth. At what value of the angular speed

, the effective magnetic field at the center of the circle will be reduced to zero? (Horizontal component of Earth’s magnetic field is 30 microTesla)

Question 3

The earth is considered as a short magnet with its centre coinciding with the geometric centre of earth. The angle of dip ϕ related to the magnetic latitude αλ as

Question 4

If a magnet is suspended at angle 30 ° to the magnet meridian, the dip of needle makes angle of 45 ° with the horizontal, the real dip is

Question 5

A horizontal straight wire 20 m long extending from to east to west falling with a speed of 5.0 m/s, at right angles to the horizontal component of the earth’s magnetic field 0.30 ×10^-4 Wb/m². The instantaneous Value of the emf (in mV) induced in the wire will be :

Question 6

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 5×10^-5 T with the declination angle ~0° and dip of θ such that

. If the voltage developed is V_B between the lower and upper side of the plane and V_W between the tips of the wings then V_B and V_W are close to:

Question 7

A geologist checks the angle of dip at a certain point and founds it to be 30˚. Now, if the vertical component of the Earth’s magnetic field is B at that place then what would have been the horizontal component?

Question 8

At two different place the angles of dip are respectively 30° and 45°. At these two place the ratio of horizontal component of earth’s magnetic field is

Question 9

The length of a magnet is large compared to its width and breadth. The time period of its oscillation in a vibration magnetometer is 2 s. The magnet is cut along its length into three equal parts and three parts are then placed on each other with their like poles together. The time period of this combination will be

Question 10

In a coil of resistance 100 Ω, a current is induced by changing the magnetic flux through it as shown in the figure. The magnitude of change in flux through the coil is:

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Nov 23JEE & BITSAT