JEE Questions for Physics Magnetism And Matter Quiz 4 - MCQExams.com


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  • If both A and R are correct and R is the correct explantion of A
  • If both A and R are correct but R is not the correct explanation of A
  • If A is correct but R is incorrect
  • If A is incorrect but R is correct
The needle of a deflection galvanometer shows a deflection of 60° due to a short bar magnet at a certain distance in tan A position. If the distance is doubled, then deflection is

  • Physics-Magnetism and Matter-77936.png
  • 2)
    Physics-Magnetism and Matter-77937.png

  • Physics-Magnetism and Matter-77938.png

  • Physics-Magnetism and Matter-77939.png
The magnetic field due to short bar magnet of magnetic dipole moment M and length 2l, on the axis at a distance z (where z >> l)from the centre of the magnet is given by the formula

  • Physics-Magnetism and Matter-77941.png
  • 2)
    Physics-Magnetism and Matter-77942.png

  • Physics-Magnetism and Matter-77943.png

  • Physics-Magnetism and Matter-77944.png

Physics-Magnetism and Matter-77946.png

  • Physics-Magnetism and Matter-77947.png
  • 2)
    Physics-Magnetism and Matter-77948.png

  • Physics-Magnetism and Matter-77949.png

  • Physics-Magnetism and Matter-77950.png

Physics-Magnetism and Matter-77952.png

  • Physics-Magnetism and Matter-77953.png
  • 2)
    Physics-Magnetism and Matter-77954.png

  • Physics-Magnetism and Matter-77955.png

  • Physics-Magnetism and Matter-77956.png
Two identical thin bar magnets each of length l and pole strength m are placed at right angles to each other, with north pole of one touching south pole of the other, then the magnetic moment of the system is
Physics-Magnetism and Matter-77958.png
  • 1 ml
  • 2 ml
  • √2 ml
  • ml/2
Two short magnets of equal magnetic moments are placed on a piece of cork which floats on water. The magnets are so placed that the axis of one produced bisects the axis of the other at right angles. Then the cork
  • moves bodily only
  • rotates only
  • has neither rotational nor translational motion
  • has rotational as well as translational motion
A compass needle is placed at the magnetic pole of earth. It
  • points N-S
  • points EW
  • becomes vertical
  • may stay in any direction
A thin bar magnet of length 2 l and breadth 2 b pole strength p and magnetic moment M is divided into four equal parts with length and breadth of each part being half of original magnet. Then the pole strength of each part is
  • p
  • p/2
  • 2p
  • p/4
Magnetic lines of force are
  • continuous
  • discontinuous
  • sometimes continuous and sometimes discontinuous
  • Nothing can be said
Magnetic field intensity due to a dipole varies as dn, where n is equal to
  • 2
  • –2
  • 3
  • –3
A closely wound solenoid of 800 turns has area of cross section 2.5 cm2. Magnetic moment associated with it, when it carries a current of 3A is
  • 0.6 JT–1
  • 0.06 JT–1
  • 6 JT–1
  • none of these
The magnet of pole strength m and magnetic moment M is cut into two pieces along its axis. Its pole strength and magnetic moment now become

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  • 2)
    Physics-Magnetism and Matter-77962.png

  • Physics-Magnetism and Matter-77963.png

  • Physics-Magnetism and Matter-77964.png
Two magnets of equal magnetic moments M each are placed as shown in Fig. The resultant magnetic moment is
Physics-Magnetism and Matter-77965.png
  • M
  • √3M
  • √2M
  • M/2
What is the resultant magnetic moment of two magnets, each of magnetic moment M in the following figures?
Physics-Magnetism and Matter-77967.png
  • √2M; zero, √3M; zero
  • √2M; zero; zero; √3M
  • √2M;√3M; zero, zero
  • None of the above
The distance between the poles of a horse shoe magnet is 4 cm. the pole strength of each pole is 40 units. The magnetic potential midway between the poles is
  • 80 units
  • 10 units
  • 20 units
  • zero
Using a bar magnet P, a vibration magnetometer has time period 2 seconds. When a bar Q (identical to P in mass and size) is placed on top of P, the time period is unchanged. Which of the following statements is true?
  • Q is of non-magnetic material
  • Q is a bar magnet identical to P, and its north pole is placed on top of P’s north pole
  • Q is of unmagnetised ferromagnetic material
  • Nothing can be said about properties of Q
The magnet A (pole strength m) of mass M kg floats on the top of another identical magnet B as shown in Fig. The vertical distance between the two magnets is d metre. The balance condition is achieved due to:
Physics-Magnetism and Matter-77970.png
  • the absence of gravitational force on A
  • the predominance of repulsive force due to B
  • superconductivity
  • the balancing of downward gravitational force on A with the upward repulsive force from B
A dip circle is so set that its needle moves freely in the magnetic meridian. In this position, the angle of dip is 40o. Now the dip circle is rotated so that the plane in which the needle moves makes an angle of 30o with the magnetic meridian. In this position, the needle will dip by an angle
  • 40º
  • 30º
  • more than 40º
  • less than 40º
Aurora Borealis is a luminous electrical discharge in the upper layers of the atmosphere, which is visible more frequently in
  • polar regions
  • equator
  • lunar eclipse
  • regions of earth’s magnetic poles
Earth’s magnetic field always has a horizontal component except at
  • equator
  • magnetic pole
  • a latitude of 60º
  • an inclination of 60º
The vertical component of earth’s magnetic field is zero at
  • magnetic equator
  • magnetic pole
  • geographic poles
  • at 90º latitude
A dip needle which is free to move in a vertical plane perpendicular to magnetic meridian will remain
  • horizontal
  • vertical
  • neither horizontal nor vertical
  • none of the above
The arms of a deflection magnetometer in the tangent B position are placed along
  • the east west direction
  • the north south direction
  • the north east-south west direction
  • the north west-south east direction

Physics-Magnetism and Matter-77973.png
  • B = H
  • B cos θ = H sin θ
  • B sin θ = H cos θ
  • B = H tan θ
A dip needle arranged to move freely in the magnetic meridian dips by an angle θ. If the vertical plane in which the needle moves is rotated through an angle α to the magnetic meridian, then the needle will dip by an angle
  • θ
  • Α
  • More than θ
  • Less than θ
The period of oscillation of a magnet in a vibration magnetometer is 2 seconds. The period of oscillation of a magnet whose magnetic moment is sixteen times that of the first magnet is
  • 1 sec
  • 4 sec
  • 8 sec
  • 0.5 sec
Two short magnets have equal pole strengths but one is twice as long as the other. The shorter magnet is placed 20 cm in tan A position from the compass needle. The longer magnet must be placed on the other side of the magnetometer for no deflection at a distance equal to
  • 20 cm
  • 20 (2)1/3 cm
  • 20 (2)2/3 cm
  • 20 (2)3/3 cm
The magnetic needle of an oscillation magnetometer makes 10 oscillations per minute under the action of earth’s magnetic field alone. When a bar magnet is placed at some distance along the axis of the needle, it makes 14 oscillations per minute. If the bar magnet is turned so that its poles interchange their positions, then the new frequency of oscillation of the needle is
  • 10 vibrations per minute
  • 14 vibrations per minute
  • 4 vibrations per minute
  • 2 vibrations per minute
A dip needle vibrates in the vertical plane perpendicular to the magnetic meridian. The time period of vibration is found to be 2 second. The same needle is then allowed to vibrate in the horizontal plane, and the time period is again found to be 2 second. Then the angle of dip is
  • 0º
  • 30º
  • 45º
  • 90º
0:0:1


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