Tag: magnetic field due to a straight current carrying conductor

Questions Related to magnetic field due to a straight current carrying conductor

For a given distance from a current element, the magnetic induction is maximum at an angle measured with respect to axis of the current. The angle is :

physics moving charges and magnetism field due to a current carrying conductor magnetic field due to a straight current carrying conductor magnetic field lines due to current

  1. $\dfrac{3\pi}{ 4}$

  2. $\dfrac{\pi }{4}$

  3. $\dfrac{\pi} {2}$

  4. $2\pi $

Show answer
Correct Option: C
Explanation:
Magnetic field due to small current element is given as 
$B=\dfrac{\mu _o}{4\pi}\dfrac{\vec{idl}\times \hat{r}} {r^2}$
$B=\dfrac{\mu _o}{4\pi}\dfrac{idlr \sin\theta}{r^3}$
$\sin\theta=1$     for     $\theta=\dfrac{\pi}{2}$

A proton is moving with velocity ${10}^{4}m/s$ parallel to the magentic field of intensity 5 tesla.The force on the proton is

physics moving charges and magnetism field due to a current carrying conductor magnetic field due to a straight current carrying conductor magnetic field lines due to current

  1. $8\times {10}^{-15}N$

  2. ${10}^{4}N$

  3. $1.6\times {10}^{-19}N$

  4. Zero

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Correct Option: D
Explanation:

Answer is D.

The magnitude and direction of F depend on the velocity of the particle and on the magnitude and direction of the magnetic field B.
When a charged particle moves parallel to the magnetic field vector, the magnetic force acting on the particle is zero.
When the particles velocity vector makes any angle with the magneticfield, the magnetic force acts in a direction perpendicular to both v and B; that is, F is perpendicular to the plane formed by v and B.
The magnitude of the magnetic force is
$F=qvBsin\theta $
where $\theta $ is the smaller angle between v and B. From this expression, we see that F is zero when v is parallel or antiparallel to B or 180) and maximum when v is perpendicular to B.
In this case, as the proton moves parallel to the magnetic field, the force is zero.

The pattern of the magnetic field around a conductor due to an electric current flowing through it depends on

physics moving charges and magnetism field due to a current carrying conductor magnetic field due to a straight current carrying conductor magnetic field lines due to current

  1. amount of current flowing through the conductor

  2. amount of voltage supplied to the conductor

  3. size of conductor

  4. shape of the conductor

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Correct Option: D
Explanation:
We know that;
$\vec B=\dfrac{\mu _0}{4\pi}\int { \dfrac { Idl\times {\vec  r  } }{ \left| { r }^{ 1 } \right| ^{ 3 } }  } $
Where, $\vec B$ is magnetic field, $\vec I$ is current.
Thus magnitude of $\vec B$ depend on I, but pattern of magnetic field depend on shape of conductor as the direction of magnetic field is obtained used Cut finger rule i.e, pointing right hand thumb in current direction, Curl fingers describes direction thus pattern.

A magnetic field due to a long straight wire carrying a current I is proportional to

physics moving charges and magnetism field due to a current carrying conductor magnetic field due to a straight current carrying conductor magnetic field lines due to current

  1. I

  2. $I^2$

  3. $I^3$

  4. $\sqrt{I}$

Show answer
Correct Option: A
Explanation:

Magnetic field due to large wire is 

$B=\dfrac{\mu _o I}{2\pi r}$
$B\propto I$

The value of $\mu$ is $4 \pi \times {10}^{-7} H {m}^{-1}$.

physics moving charges and magnetism field due to a current carrying conductor magnetic field due to a straight current carrying conductor magnetic field lines due to current

  1. True

  2. False

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Correct Option: A
Explanation:

The physical constant $μ _0$ commonly called the vacuum permeability, permeability of free space, ... In the reference medium of classical vacuum, μ0 has an exact defined value: .... The value of $μ _0$ was chosen such that the rmks unit of current is equal in size to the ampere in the emu system: μ0 is defined to be $4π × 10^{−7} H/m.$

The value of magnetic field due to a small element of current carrying conductor at a distance r and lying on the plane perpendicular to the element of conductor is

physics moving charges and magnetism field due to a current carrying conductor magnetic field due to a straight current carrying conductor magnetic field lines due to current

  1. Zero

  2. Maximum

  3. Inversely proportional to the current

  4. None of the above

Show answer
Correct Option: B
Explanation:

The Biot Savart law is used for computing the resultant magnetic field B at position r generated by a steady current I.  According to it $B=\frac {\mu _0 I } {4\pi} \int \frac {I\vec{dl} \times \vec{r}} { r^3}$.
So magnetic field at a distance r and lying on the plane perpendicular ($\pi /2$)to the element of conductor is maximum .

The magnetic field due to current flowing in a ling straight conductor is directly proportional to the current and inversely proportional to the distance of the point of observation from the conductor. What is this law known as?

physics moving charges and magnetism field due to a current carrying conductor magnetic field due to a straight current carrying conductor magnetic field lines due to current

  1. Blonde-Rey law

  2. Biot-Savart's law

  3. Beer-Lambert law

  4. Ampere's law

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Correct Option: B

A current of i ampere is flowing in an equilateral triangle of side a. The magnetic induction at the centroid will be?

physics moving charges and magnetism field due to a current carrying conductor magnetic field due to a straight current carrying conductor magnetic field lines due to current

  1. $\dfrac{\mu _i}{3\sqrt{3}\pi a}$

  2. $\dfrac{3\mu _i}{2\pi a}$

  3. $\dfrac{5\sqrt{2}\mu _i}{3\pi a}$

  4. $\dfrac{9\mu _i}{2\pi a}$

Show answer
Correct Option: D
Explanation:
a = length of side of equilateral triangle 

r = perpendicular distance of each side from centroid $=\frac { \sqrt { 3a }  }{ 6 } $

θ = angle by each end of each side at centroid = 60

Using Biot-savart's law , magnetic field at the centroid by each side is given as 

$B=\frac { μ }{ 4π } \ast \frac { i }{ r } \ast (Sinθ+Sinθ)$

$B=\frac { μ }{ 4π } \left( \frac { i }{ \sqrt { 3 }  } \frac { a }{ 6 }  \right) (Sin60+Sin60)$

$B=\frac { μ }{ 4π } \left( \frac { 6i }{ \sqrt { 3a }  } \frac { \sqrt { 3 }  }{ 2 }  \right) $

$B=\frac { μ }{ 4π } \frac { 6i }{ a } $

total magnetic field by all three sides is given as 

$B''=3B=3\frac { μ }{ 4π } \frac { 6i }{ a } $

$B''=\frac { μ }{ 2π } \frac { 9i }{ a } $




A thermistor:

physics electromagnetic forces oersted experiment oersted's experiment magnetic field due to a straight current carrying conductor

  1. Is a thermally sensitive resistor

  2. Is made of a semiconductor

  3. Has negative temperature coefficient of resistance

  4. All the above

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Correct Option: D
Explanation:
A thermistor is a type of resistor whose resistance depends on temperature, more than in standard resistor. The word is a combination of thermal and resistor. They are widely used as inrush current limiters, temperature sensors, self -resetting overcurrent protectors, and self-regulating heating elements.
It is made up of semiconductors and has a negative temperature coefficient of resistance.

Thermistor has a resistance of ________

physics electromagnetic forces oersted experiment oersted's experiment magnetic field due to a straight current carrying conductor

  1. 250 to 500 k ohms

  2. 50 to 10 k ohms

  3. 1 to 1 k ohms

  4. 100 to 100 k ohms

Show answer
Correct Option: D
Explanation:

Thermistor has a resistance range of 100 to 100 k. Thermistor consists of a mixture of metallic oxides of manganese, nickel, cobalt, copper, iron and uranium.