Tag: physics

Questions Related to physics

State whether the given statement is true or false:

Fluid friction is more than solid friction.

physics dynamics - explaining motion air resistance fluid friction moving through fluids

  1. True

  2. False

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Correct Option: B
Explanation:

Static friction is the force that is the greatest. This is because it opposes motion the strongest between the various types of friction. Friction is greatest in the absent of lubrication,and since there is presence of fluid lubricant in fluid friction it has less friction as compared to solid friction,and in solid friction there is no presence of any lubricant.Hence the given statement is false.

A man of mass $m$ walks from end $A$ to the other end $B$ of a boat of mass $M$ and length $l$. The coefficient of friction between the man and the boat is $ \mu $ and neglect any resistive force between the boat and the water.

physics dynamics - explaining motion air resistance fluid friction moving through fluids

  1. If the man runs at his maximum acceleration, the acceleration of the boat is $ (m/M)g $.

  2. The maximum time take by the men to reach the other end of the boat is $ \sqrt { \dfrac { 2Ml }{ (M+m)\mu g } } $.

  3. If the man runs at his maximum acceleration, the acceleration of the boat is $ \dfrac { m }{ m+M } \mu g $.

  4. The minimum time take by the men to reach the other end of the boat is $ \sqrt { \dfrac { 2ml }{ (M+m)\mu g } } $.

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Correct Option: A,B

Out of given paramagnetic substance (Calcium, Chromium, Oxygen and Tungsten) which substance has maximum susceptibility?

physics magnetism and matter paramagnetic material classification of magnetic material magnetism

  1. Calcium

  2. Chromium

  3. Oxygen

  4. Tungsten

Show answer
Correct Option: B
Explanation:

Susceptibility at the standard temperature, $T=300K$

Calcium $\rightarrow 1.9\times 10^{-5}$ 
Chromium $\rightarrow 2.7\times 10^{-4}$
 Oxygen $\rightarrow 2.1\times 10^{-6}$
Tungsten $\rightarrow 6.8\times 10^{-5}$
Chromium have maximum susceptibility.
The correct option is B.

A paramagnetic liquid is taken in a U-tube and arranged so that one of its limbs is kept between pole pieces of the magnet. The liquid level in the limb is

physics magnetism and matter paramagnetic material classification of magnetic material magnetism

  1. goes down

  2. rises up

  3. remains same

  4. first goes down and then rise

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Correct Option: B
Explanation:

When a paramagnetic liquid is taken in U-tube and one arm is placed between the poles of strong magnet, the liquid is feebly attracted by the magnet. Therefore, the level of the solution in the arm rises.

The magnetic susceptibility of a paramagnetic material at $-73^0$ is $0.0075$, its value at $-173^0$C will be

physics magnetism and matter paramagnetic material classification of magnetic material magnetism

  1. $0.0045$

  2. $0.0030$

  3. $0.015$

  4. $0.0075$

Show answer
Correct Option: C
Explanation:
Given,
$X=0.0075 \,\,at\,\,\, T=-73^{\circ}$
Curie's law, $X=\cfrac{C}{T}$
$X _{1} \propto \cfrac{1}{T _{1}}$
$\therefore \cfrac{X _{1}}{X _{2}}=\cfrac{T _{2}}{T _{1}}$
$X _{2}=X _{1}\times \cfrac{T _{1}}{T _{2}}=0.0075\times \cfrac{273-73}{2.73-173}=0.015$

Assertion : Paramagnetic substances get weakly attracted to a magnet.
Reason : They have tendency to move from a region of strong magnetic field to weak magnetic field

physics magnetism and matter paramagnetic material classification of magnetic material magnetism

  1. If both assertion and reason are true and reason is the correct explanation of assertion.

  2. If both assertion and reason are true and reason is not the correct explanation of assertion.

  3. If assertion is true but reason is false.

  4. If both assertion and reason are false

Show answer
Correct Option: C
Explanation:

Paramagnetic substances have tendency to move from a region of weak magnetic field to strong magnetic field i.e., they get weakly attracted to a magnet.

Consider the following statements I and II.
(I) Paramagnetism is explained by domain theory 
(II) Susceptibility of a diamagnetic substance is independent of temperature.
Identify the correct choice from the following. 

physics magnetism and matter paramagnetic material classification of magnetic material magnetism

  1. Both I and II are correct

  2. Both I and II are incorrect

  3. I is correct and II is incorrect.

  4. I is incorrect and II is correct

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Correct Option: D

Assertion(A) : Earth's magnetic field inside a closed iron box is less as compared to the outside.
Reason(R) : The magnetic permeability of iron is low.

physics magnetism and matter paramagnetic material classification of magnetic material magnetism

  1. Both A, R are true and R is the correct explanation of A

  2. Both A, R are true and R is not correct explanation of A

  3. A is true R is false

  4. A is false R is true

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Correct Option: C

The meniscus of a liquid contained in one of the limbs of a narrow U-tube is held electromagnet with the meniscus in line with the field. The liquid is seen to rise. This indicates that the liquid is

physics magnetism and matter paramagnetic material classification of magnetic material magnetism

  1. anti-ferromagnetic

  2. paramagnetic

  3. diamagnetic

  4. non-magnetic

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Correct Option: B
Explanation:

Paramagnetic liquid tends to flow from region of weaker magnetic fields to stronger magnetic fields..

Metals getting magnetised by orientation of atomic magnetic moments in external magnetic field are called

physics magnetism and matter paramagnetic material classification of magnetic material magnetism

  1. diamagnetics

  2. paramagnetics

  3. ferromagnetics

  4. antimagnetics

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Correct Option: B
Explanation:

In paramagnetic metals, magnetism is acquired by orientation of atomic magnetic  dipoles.