Magnetism and Matter Easy Questions and Answers | Page - 3

Magnetism and Matter

If θ₁ and θ₂ be the apparent angles of dip observed in two vertical planes at right angles to each other, then the true angle of dip θ is given by :-

1. tan¹θ = tan¹θ₁ + tan¹θ₂
1. cot¹θ = cot¹θ₁ – cot¹θ₂
1. tan¹θ = tan¹θ₁ – tan¹θ₂
1. cot¹θ = cot¹θ₁ + cot¹θ₂

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If θ₁ and θ₂ are opparent angles of dip
Let α be the angle which one of the plane make with the magnetic meridian.
tan θ₁ = υ
H cos α

i.e.,cos α = υ      ....(i)
H tan θ₁

tan θ₂ = υ ,
H sin α

i.e.,sin α = υ      ....(ii)
H tan θ₂

Squaring and adding (i) and (ii), we get

i.e., 1 = V² [cot²θ₁ - cot²θ₂]
H²

i.e., cot² θ = cot²θ₁ + cot² θ₂

Correct Option: D

If θ₁ and θ₂ are opparent angles of dip
Let α be the angle which one of the plane make with the magnetic meridian.
tan θ₁ = υ
H cos α

i.e.,cos α = υ      ....(i)
H tan θ₁

tan θ₂ = υ ,
H sin α

i.e.,sin α = υ      ....(ii)
H tan θ₂

Squaring and adding (i) and (ii), we get

i.e., 1 = V² [cot²θ₁ - cot²θ₂]
H²

i.e., cot² θ = cot²θ₁ + cot² θ₂

The magnetic susceptibility is negative for :

1. diamagnetic material only
1. paramagnetic material only
1. ferromagnetic material only
1. paramagnetic and ferromagnetic materials

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Magnetic susceptibility χ for dia-magnetic materials only is negative and low |χ| = –1; for paramagnetic
substances low but positive |χ| = 1 and for ferromagnetic substances positive and high |χ| = 10².

Correct Option: A

Magnetic susceptibility χ for dia-magnetic materials only is negative and low |χ| = –1; for paramagnetic
substances low but positive |χ| = 1 and for ferromagnetic substances positive and high |χ| = 10².

There are four light–weight–rod samples A,B,C,D separately suspended by threads. A bar magnet is slowly brought near each sample and the following observations are noted
(i)A is feebly repelled
(ii)B is feebly attracted
(iii)C is strongly attracted
(iv)D remains unaffected
Which one of the following is true ?

1. B is of a paramagnetic material
1. C is of a diamagnetic material
1. D is of a ferromagnetic material
1. A is of a non–magnetic material

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A → diamagnetic
B → paramagnetic
C → Ferromagnetic
D → Non magnetic

Correct Option: A

A → diamagnetic
B → paramagnetic
C → Ferromagnetic
D → Non magnetic

A bar magnet is oscillating in the earth’s magnetic field with a period T. What happens to its period of motion, if its mass is quadrupled

1. motion remains simple harmonic with new period = T/2
1. motion remains simple harmonic with new period = 2 T
1. motion remains simple harmonic with new period = 4T
1. motion remains simple harmonic and the period stays nearly constant

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The time period of a bar magnet in a magnetic field is given by.
T = 2π√I/MB;
Here, I = moment of inertia ∝ m, M = moment of magnet, B = magnetic field.
T ∝ √I ∝ √m; so, T becomes twice as mass becomes four times.

Correct Option: B

The time period of a bar magnet in a magnetic field is given by.
T = 2π√I/MB;
Here, I = moment of inertia ∝ m, M = moment of magnet, B = magnetic field.
T ∝ √I ∝ √m; so, T becomes twice as mass becomes four times.

The magnetic moment of a diamagnetic atom is

1. equal to zero
1. much greater than one
1. 1
1. between zero and one

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The magnetic moment of a diamagnetic atom is equal to zero.

Correct Option: A

The magnetic moment of a diamagnetic atom is equal to zero.