Tag: properties of magnet

Questions Related to properties of magnet

A device used by the sailors to find the direction in which their ship is moving is called .................

properties of magnet magnetism physics neutral points magnetic poles and magnetic compass magnetic field

  1. horse shoe

  2. curve

  3. magnetic field

  4. magnetic needle

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Correct Option: D
Explanation:

A device used by the sailors to find the direction in which their ship is moving is called magnetic needle.
A compass contains a magnetic needle pivoted in a horizontal plane that indicates the direction of magnetic north at points on the earth's surface. It is an instrument containing a freely suspended magnetic element which displays the direction of the horizontal component of the Earth's magnetic field at the point of observation.
It is the oldest instrument for navigation and has been a vital tool for navigators at sea for centuries.

State whether true or false:

A tracing needle is used by the sailor for navigation.  

properties of magnet magnetism physics neutral points magnetic poles and magnetic compass magnetic field

  1. True

  2. False

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Correct Option: B
Explanation:

Magnetic compass is used for navigation while tracing needle is used for tracing magnetic field lines. 

The presence of magnetic field at a point can be detected by

properties of magnet magnetism physics neutral points magnetic poles and magnetic compass magnetic field

  1. ammeter 

  2. galvanometer

  3. a compass needle

  4. strong magnet

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Correct Option: C
Explanation:

A compass can be used to detect presence of magnetic field as it will deflect from its N-S direction to direction if magnetic field at that point.

The magnetic compass is not useful for navigation near the magnetic poles, since

properties of magnet magnetism physics neutral points magnetic poles and magnetic compass magnetic field

  1. $R=0$

  2. $V=0$

  3. $H=0$

  4. $\theta={0}^{o}$

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Correct Option: C
Explanation:

Near magnetic poles, $H=0$, therefore, magnetic compass will not work.

Two parallel conductors are separated by 5cm. They carry 6A and 2A in the same direction. Between them the location from first at which magnetic needle lies along $B _H$ is

properties of magnet magnetism physics neutral points magnetic poles and magnetic compass magnetic field

  1. 1.25 cm

  2. 3.75 cm

  3. 2.5 cm

  4. no point exist

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Correct Option: B

A magnetic needle oscillates in a horizontal plane with a period $T$ at a place where the angle of dip is $60^0$. When the same needle is made to oscillate in a vertical plane coinciding with the magnetic meridian, its period will be 

properties of magnet magnetism physics neutral points magnetic poles and magnetic compass magnetic field

  1. $\frac{T}{\sqrt 2}$

  2. T

  3. 2T

  4. 6T

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Correct Option: A

When a current of $1$ ampere is passed in a coil lying in the magnetic meridian then a magnetic needle at its centre gives some deflection. If the current in the coil is increased to $\sqrt8$ ampere then at what distance from the centre of the coil will the deflection of needle remains underchanged?

properties of magnet magnetism physics neutral points magnetic poles and magnetic compass magnetic field

  1. $2R$

  2. $4R$

  3. $8R$

  4. $R$

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Correct Option: B

If E and B denote electronic and magnetic field respectively, which of the following is dimensionless?

properties of magnet magnetic field moving charges and magnetism magnetic effects of current and magnetism physics

  1. $\sqrt { { \mu } _{ 0 }{ \varepsilon } _{ 0 } } \dfrac { E }{ B } $

  2. $ { { \mu } _{ 0 }{ \varepsilon } _{ 0 } } \dfrac { E }{ B } $

  3. ${ \mu } _{ 0 }{ \varepsilon } _{ 0 }{ \left( \dfrac { B }{ E } \right) }^{ 2 }$

  4. $\dfrac { E }{ { \varepsilon } _{ 0 } } \dfrac { { \mu } _{ 0 } }{ B } $

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Correct Option: A
Explanation:

We know that Velocity of light  $C _0=\dfrac{1}{\sqrt{\mu _0 \epsilon _0}}$

And also velocity of electromagnetic wave $V=\dfrac{E}{B}$
 $[C _0]=\left[\dfrac{1}{\sqrt{\mu _0 \epsilon _0}}\right]=[LT^{-1}]$

 $[V]=\left[\dfrac{E}{B}\right]=[LT^{-1}]$

$\left[\sqrt { { \mu } _{ 0 }{ \varepsilon } _{ 0 } } \dfrac { E }{ B } \right]=[LT^{-1}]^{-1}[LT^{-1}]=[M^0L^0T^0]$    (Dimention less),

Option A

Ratio of magnetic fields at 10 cm and 20 cm from a infinitely long current carrying wire is

properties of magnet magnetic field moving charges and magnetism magnetic effects of current and magnetism physics

  1. 1 : 2

  2. 1 : 4

  3. 2 : 1

  4. 4 : 1

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Correct Option: A

A large metal sheet carries an electric current along its surface. Current per unit length is $\lambda $. Magnetic field near the metal sheet is

properties of magnet magnetic field moving charges and magnetism magnetic effects of current and magnetism physics

  1. $\dfrac{\lambda { \mu } _{ 0 }}{2} $

  2. $\dfrac{\lambda { \mu } _{ 0 }}{2 \pi} $

  3. $\lambda { \mu } _{ 0 }$

  4. $ { \mu } _{ 0 }2\lambda \pi $

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Correct Option: A