Two magnets held together in earth's magnetic field when the same polarity together causes 12vib / min and when opposite poles 4vib / min . What is the ratio of magnetic moments?

Correct answer: 1.25 Here we use sum and difference method. M _ 2 M _ 1 = T _ 2 ^ 2 - T _ 1 ^ 2 T _ 2 ^ 2 + T _ 1 ^ 2 Where T _ 1 and T _ 2 are time periods T ∝ (1)/(n) ( ∵ nisfrequency . ) ⇒ M _ 1 M _ 2 = n _ 1 ^ 2 + n _ 2 ^ 2 n _ 1 ^ 2 - n _ 2 ^ 2 = (12) ^ 2 + (4) ^ 2 (12) ^ 2 - (4) ^ 2 = (144 + 16)/(144 - 16) = (10)/(8) = 1 . 25

NTA Abhyas 2020

Exam: NTA Abhyas
Year: 2020
Subject: Physics
Chapter: Magnetic Properties of Matter

NTA Abhyas 2020 · Physics · Magnetic Properties of Matter

Two magnets held together in earth's magnetic field when the same...

Two magnets held together in earth's magnetic field when the same polarity together causes

12\text{v}\text{i}\text{b} / min

and when opposite poles

4\text{v}\text{i}\text{b} / \text{m}\text{i}\text{n}

. What is the ratio of magnetic moments?

Correct answer

1.25

Step-by-step solution

Here we use sum and difference method.

\dfrac{{M}_{2}}{{M}_{1}} = \dfrac{{T}_{2}^{2} - {T}_{1}^{2}}{{T}_{2}^{2} + {T}_{1}^{2}}

Where

{T}_{1}

and

{T}_{2}

are time periods

T ∝ \dfrac{1}{n}

( ∵ nisfrequency . )

⇒

\dfrac{{M}_{1}}{{M}_{2}} = \dfrac{{n}_{1}^{2} + {n}_{2}^{2}}{{n}_{1}^{2} - {n}_{2}^{2}}

= \dfrac{{\left(12\right)}^{2} + {\left(4\right)}^{2}}{{\left(12\right)}^{2} - {\left(4\right)}^{2}} = \dfrac{144 + 16}{144 - 16} = \dfrac{10}{8} = 1 . 25

Practice Magnetic Properties of Matter on Quantrex Academy →

More from Magnetic Properties of Matter

A solenoid has a core made of material with relative permeability 400 . The magnetic… JEE Main 2026 Two identical small bar magnets each of dipole moment 3 5 J/T are placed at a center to… JEE Main 2026 Given below are two statements: one is labelled as Assertion (A) and the other is… JEE Main 2026 Given below are two statements : one is labelled as Assertion (A) and the other is… JEE Main 2025 The percentage increase in magnetic field (B) when space within a current carrying… JEE Main 2025 A solenoid having area A and length ' l ' is filled with a material having relative… JEE Main 2025 The relationship between the magnetic susceptibility (χ) and the magnetic permeability… JEE Main 2025 A bar magnet has total length 2 l=20 units and the field point P is at a distance d=10… JEE Main 2025 Full Magnetic Properties of Matter list All NTA Abhyas JEE Main PYQs