KCET 2019 | Magnetism and Matter Question 9 | Physics

A magnetic needle has a magnetic moment of $$5 \times 10^{-2} \mathrm{~Am}^2$$ and moment of inertia $$8 \times 10^{-6} \mathrm{~kgm}^2$$. It has a period of oscillation of $$2 \mathrm{~s}$$ in a magnetic field $$\mathbf{B}$$. The magnitude of magnetic field is approximately?

$$1.6 \times 10^{-4} \mathrm{~T}$$

$$0.4 \times 10^{-4} \mathrm{~T}$$

$$3.2 \times 10^{-4} \mathrm{~T}$$

$$0.8 \times 10^{-4} \mathrm{~T}$$

KCET 2019

MCQ (Single Correct Answer)

-0

A circular current loop of magnetic moment $$M$$ is in a arbitrary orientation in an external uniform magnetic field $$\mathbf{B}$$. The work done to rotate the loop by $$30^{\circ}$$ about an axis perpendicular to its plane is

$$M B$$

$$\sqrt{3} \frac{M B}{2}$$

$$\frac{M B}{2}$$

zero

KCET 2019

MCQ (Single Correct Answer)

-0

In a permanent magnet at room temperature

magnetic moment of each molecule is zero

the individual molecules have non zero magnetic moment which are all perfectly aligned.

domains are partially aligned

domains are all perfectly aligned

KCET 2018

MCQ (Single Correct Answer)

-0

Needles $N_1, N_2$ and $N_3$ are made of a ferromagnetic, a paramagnetic and adiamagnetic substance, respectively. A magnet when brought close to them will

attract all three of them

attract $N_1$ strongly, $N_2$ weakly and repel $N_3$ weakly

attract $N_1$ strongly but repel $N_2$ and $N_3$ weakly

attract $N_1$ and $N_2$ strongly but repel $N_3$

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