Tag: magnetic field due to a straight current carrying conductor

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

Which of the following observations are true for Hans Oersteds experiment?
a. When current passes through the wire the compass needle comes to rest in a direction along the Earths magnetic field.
b. When placed just above the wire, North Pole of the compass needle deflects towards the east when current is passes from A to B.
c. When placed just below the wire, North Pole of the compass needle deflects towards the east when current is passes from B to A i.e. on reversing the direction of current

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

  1. a and c

  2. a and b

  3. b and c

  4. All of the above

Show answer
Correct Option: C
Explanation:

Oersted conducted an experiment to study the magnetic effect of electric current. In this experiment he observed the deflections of a compass needle placed in close proximity of an electric wire carrying current. He observed that in the absence of current the needle came to rest in Earths North-south direction under the influence of Earths magnetic field. However, when the needle was kept below the wire and current was passed from A to B the north pole of the needle deflected towards the west and on reversing the direction of the current from B to A, it deflected towards the east. Similarly, when the needle was kept above the wire and current was passed from A to B the north pole of the needle deflected towards the east and on reversing the direction of the current from B to A, it deflected towards the west. This indicates that the direction of the magnetic field depends on the direction of current.

When current passes through the circuit a compass needle rests in which direction (with respect to the Earth)?

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

  1. South-north

  2. North-south

  3. East-west

  4. West-east

Show answer
Correct Option: A
Explanation:

The earth acts like a huge magnet. Thus in the absence of electric current a compass needle always comes to rest in Earths North-south direction. However, when current passes through the circuit the needle comes to rests in the direction opposite to the magnetic field of Earth i.e. South-North direction.

State whether True or False :

If electric current is passed through metal body then it behaves as magnet.

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

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

If electric current is passed through metal body then it behaves as magnet. passing an electric current through iron does not produce a magnet. But if you pass a direct current through a coil wound around the piece of iron, you will magnetize it. Passing a direct electric current through the same coil with no iron inside the coil will still produce a magnetic field that behaves just like a magnet. Similarly, passing a direct current through a coil around a piece of Bismuth will create the same magnetic field which behaves just like a magnet.

Who first discovered the relationship between electricity and magnetism?

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

  1. Faraday

  2. Newton

  3. Maxwell

  4. Oersted

Show answer
Correct Option: D
Explanation:

Oersted discovered the relationship between electricity and magnetism.

Chose the correct statement from the following:

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

  1. Electric current is a scalar quantity

  2. Charge carries in metals are ions

  3. The area of current- time graph gives charge

  4. A charge in motion produces both electric and magnetic field

Show answer
Correct Option: A,C,D
Explanation:
$(i)$ Option- $A$ is correct, since current has no directional attribute to it, it is a scalar quantity.
$(ii)$ Option- $B$ is correct, Charge carries in metal are free electrons whereas in electrolytic solution they are ions
$(iii)$ Option- $C$ is correct because $i=\dfrac{da}{dt}\Rightarrow =i dt \Rightarrow a=\displaystyle \int{i. dt}$
$\displaystyle \int{i. dt}$ is the area under current-time graph
$(iv)$ Option- $D$ is correct, charge in motion produces current which in term produces magnetic field.

Two long parallel wires A and B separated by a distance d, carry currents $i _1$ and $i _2$ respectively in the same direction. Write the following steps in a sequential order to find the magnitude of the resultant magnetic field at a point 'P', which is between the wires and is a distance '$x$' from the wire A.
(All the physical quantities are measured in SI units)
(a) Note the given values of $i _1, i _2$, $d$ and $x$.
(b) Write the formula to find the magnetic field due to a long straight current carrying wire i.e. $\displaystyle B=\frac{\mu _0 i}{2 \pi r}$
(c) Find the directions of the magnetic field at 'P' due to two wires A and B, using right hand thumb rule.
(d) Determine the magnetic field at P due to wire A, using $B _1 \displaystyle = \frac{\mu _0 i _1}{2 \pi x}$
(e) If the directions of magnetic field are same, then the resultant magnitude is equal to the sum of $B _1$ and $B _2$.
(f) Determine the magnetic field $B _2$ due to wire B at point P, ie. $B _2 = \displaystyle \frac{\mu _o i _2}{2 \pi (d-x)}$
(g) If the directions of magnetic fields are opposite to each other, then the resultant magnitude is equal to the difference of $B _1$ and $B _2$.

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

  1. $d f c e g b a$

  2. $c d f e g b a$

  3. $a c b d f e g$

  4. $a b d f c e g$

Show answer
Correct Option: D

Consider a region where both uniform electric and magnetic fields E and B are present both along the z-axis. A positively charged particle of charge and mass is released from the origin with an initial velocity ${{\text{V}} _e}\hat i$. Which of the following option(s) are correct?

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

  1. (A)The y coordinate of the particle at time ${\text{t}} = \frac{{\pi {\text{M}}}}{{{\text{qB}}}}{\text{ is}}\frac{{ - 2{\text{mv}}}}{{{\text{qB}}}}$

  2. (B)The distance between two consecutive point on the z-axis where the particle touches the Z-axis is an odd multiple of a constant distance.

  3. (C)The distance between two consecutive point on the z-axis where the particle touches the Z-axis is an even multiple of a constant distance.

  4. (D)The time after which the particle touches the z-axis is $\frac{{2\pi {\text{m}}}}{{{\text{qB}}}}$

Show answer
Correct Option: A

SI unit of permittivity of free space 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. Farad

  2. Weber

  3. ${ C }^{ 2 }{ N }^{ -1 }{ m }^{ -2 }$

  4. ${ C }^{ 2 }{ N }^{ -1 }{ m }^{ -1 }$

Show answer
Correct Option: C
Explanation:

Coulombic force between two charges is given by

F=1/4π€ (q'.q″/r²)

From here, the SI UNIT of permittivity comes out is

= coulomb²/Newton-meter²

C²/N-m²

If an electron is moving with velocity $\bar{v}$ produces a magnetic field $\bar{B}$, then

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. the direction of field $\bar{B}$ will be same as the direction of velocity $\bar{v}$

  2. the direction of field $\bar{B}$ will be opposite as the direction of velocity $\bar{v}$

  3. the direction of field $\bar{B}$ will be perpendicular as the direction of velocity $\bar{v}$

  4. the direction of field $\bar{B}$ does not depend upon the direction of velocity $\bar{v}$

Show answer
Correct Option: C
Explanation:

According to Biot-Savart's law, the magnetic field
$\displaystyle \overset{\rightarrow}{B} = \frac{\mu _o}{4 \pi} . \frac{q (\overset{\rightarrow}{v} \times \overset{\rightarrow}{r} ) }{r^3}$
The direction of $\overset{\rightarrow}{B}$ will be along $\overset{\rightarrow}{v} \times \overset{\rightarrow}{r}$ i.e. perpendicular to the plane containing $\overset{\rightarrow}{v}$ and $\overset{\rightarrow}{r}$.

Biot-Savart law indicates that the moving electrons (velocity $\bar v$ ) produce a magnetic field $\bar B$ such that:

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. $\bar B \perp \bar v$

  2. $\bar B \parallel \bar v$

  3. it obeys inverse cube law.

  4. it is along the line joining the electron and point of observation.

Show answer
Correct Option: A
Explanation:

Magnetic field produced by charges moving with velocity $\bar v$, at a distance r is $ \bar B$ = $\left ( \dfrac{\mu _0}{4\pi } \right )$.q$\dfrac{\bar v \times \hat r}{r^2}$
Therefore $\bar B \perp \bar v$