Magnetic Field due to a Current-carrying Conductor Questions in English

(B) When a rectangular coil of copper is rotated in a magnetic field,the magnetic flux linked with the coil changes continuously.
According to Faraday's law of electromagnetic induction,this change in flux induces an electromotive force $(EMF)$ and consequently an induced current in the coil.
As the coil rotates,the side of the coil that was moving upwards starts moving downwards after completing a half revolution.
Due to this change in the direction of motion relative to the magnetic field lines,the direction of the induced current reverses after every half revolution.
Therefore,the direction of the induced current changes once in each half revolution.

(B) The magnetic field lines,produced around a straight current-carrying conductor,are concentric circles.
Their centres lie on the wire.

(C) Electromagnetic induction is the phenomenon where an electric current is produced in a conductor or coil due to a changing magnetic field.
When there is relative motion between a magnet and a coil,the magnetic flux linked with the coil changes.
This change in magnetic flux induces an electromotive force $(EMF)$ and consequently an induced current in the coil.
Therefore,producing induced current in a coil due to relative motion between a magnet and the coil is the correct definition.

(A) When a bar magnet is moved relative to a coil of insulated copper wire,the magnetic flux linked with the coil changes.
According to Faraday's law of electromagnetic induction,this change in magnetic flux induces an electromotive force $(EMF)$ and consequently an electric current in the coil.
When the bar magnet is pushed into the coil,the galvanometer needle deflects momentarily in a particular direction,indicating the presence of an induced current.

(B) According to the principle of electromagnetic induction,a current is induced in a coil when there is a change in the magnetic flux linked with it.
When a bar magnet is moved relative to a coil,the magnetic field lines passing through the coil change,inducing an electric current.
When the bar magnet is withdrawn from inside the coil,the direction of the change in magnetic flux is reversed compared to when it was inserted.
Consequently,a current is induced in the opposite direction,causing the galvanometer needle to deflect momentarily in the opposite direction.

(C) According to the principle of electromagnetic induction,an electric current is induced in a coil only when there is a change in the magnetic flux linked with it.
When a bar magnet is moved relative to the coil,the magnetic flux changes,inducing a current.
However,when a bar magnet is held stationary inside the coil,the magnetic flux linked with the coil remains constant.
Since there is no change in magnetic flux,no current is induced in the coil.
Therefore,the galvanometer will show no deflection.

(C) The direction of magnetic field lines inside a current-carrying loop is from the South pole to the North pole, and outside the loop, it is from the North pole to the South pole.
Given that the magnetic field lines point from $B$ to $A$, this indicates that the face at $A$ acts as the North pole and the face at $B$ acts as the South pole.
According to the right-hand rule for a circular loop, if the current appears anti-clockwise when viewed from a face, that face acts as the North pole ($N-$ pole).
Since the current is seen as anti-clockwise from point $A$, the face at $A$ behaves as the North pole.
Therefore, the $N-$ pole of the resultant magnet is on the face close to $A$.

(D) current-carrying solenoid behaves exactly like a bar magnet.
$1$. The magnetic field lines inside a solenoid are parallel straight lines,indicating a uniform magnetic field.
$2$. The strong magnetic field inside can magnetize soft iron to create an electromagnet.
$3$. Reversing the current direction reverses the polarity of the poles.
$4$. Since a solenoid behaves like a bar magnet,its magnetic field pattern is identical to that of a bar magnet. Therefore,the statement that the patterns are different is incorrect.

(C) According to Faraday's law of electromagnetic induction,an induced current is produced in a coil when the magnetic flux linked with it changes.
When the key is inserted,the current in the first coil increases from zero to a steady value,causing the magnetic field linked with the second coil to change,which induces a momentary current in the second coil,resulting in a deflection in the galvanometer.
Once the current becomes steady,the magnetic flux becomes constant,and the deflection drops to zero.
When the key is removed,the current in the first coil decreases from its steady value to zero,causing the magnetic flux linked with the second coil to change again,but in the opposite direction,which induces a momentary current in the opposite direction,resulting in a deflection in the opposite direction in the galvanometer.

(A) According to the Right-Hand Thumb Rule,if you hold the current-carrying wire in your right hand such that your thumb points in the direction of the current (West),then your curled fingers represent the direction of the magnetic field lines.
$1$. The current flows from East to West.
$2$. Above the wire,the magnetic field lines point towards the North.
$3$. Below the wire,the magnetic field lines point towards the South.
Therefore,the direction of the magnetic field is from North to South directly below the wire.

(N/A) According to the Right-Hand Thumb Rule, if you hold the current-carrying conductor in your right hand such that your thumb points in the direction of the current, your fingers will curl in the direction of the magnetic field lines.
For the given conductor with current flowing upwards, the magnetic field lines at point $P$ (to the right) go into the plane of the paper, and at point $Q$ (to the left), they come out of the plane of the paper.
The strength of the magnetic field produced by a straight current-carrying conductor is inversely proportional to the distance from the conductor $(B \propto 1/r)$.
Since $r_1 > r_2$, the point $Q$ is closer to the conductor than point $P$.
Therefore, the strength of the magnetic field will be larger at point $Q$.

(N/A) The deflection of the magnetic compass increases.
Reason: The strength of the magnetic field produced by a current-carrying straight conductor is directly proportional to the magnitude of the current flowing through it $(B \propto I)$. Therefore,increasing the current increases the magnetic field strength,which exerts a greater force on the magnetic needle,resulting in a larger deflection.

(N/A) The magnetic field lines around a straight current-carrying conductor are concentric circles with the wire as the center. The plane of these circles is perpendicular to the wire.
Right-Hand Thumb Rule: This rule states that if you imagine holding a current-carrying straight conductor in your right hand such that your thumb points in the direction of the current,then your fingers will wrap around the conductor in the direction of the magnetic field lines.

(N/A) $1$. Magnetic field due to a circular loop: When a current flows through a circular loop,the magnetic field lines are circular near the wire. As we move towards the center of the loop,the arcs of these circles become larger and appear as straight lines at the center. The direction of the magnetic field can be determined using the Right-Hand Thumb Rule.
$2$. Effect of $n$ turns: The magnetic field produced by each turn of the coil adds up in the same direction. Since the current in each turn flows in the same direction,the magnetic effects of all the turns are additive. Therefore,if a coil has $n$ turns,the total magnetic field produced at any point is $n$ times the magnetic field produced by a single turn.

(N/A) Electromagnetic induction is the phenomenon where a changing magnetic field in a conductor induces an electric current in another conductor or circuit.
Experiment:
$1$. Take two coils of copper wire having a large number of turns (say $50$ and $100$ turns respectively) and wind them over a non-conducting cylindrical roll.
$2$. Connect the terminals of the first coil (Coil-$1$) in series with a battery and a plug key $(K)$.
$3$. Connect the terminals of the second coil (Coil-$2$) to a galvanometer $(G)$.
$4$. When the key $K$ is closed,a current flows through Coil-$1$,creating a magnetic field. The galvanometer needle in Coil-$2$ shows a momentary deflection,indicating that a current is induced in Coil-$2$.
$5$. When the key $K$ is opened,the current in Coil-$1$ stops,causing the magnetic field to change. The galvanometer needle deflects in the opposite direction,indicating an induced current in the opposite direction.
$6$. This experiment demonstrates that a change in the magnetic field associated with a coil induces a current in it.

(N/A) The magnetic field lines around a current-carrying straight conductor are in the form of concentric circles. The center of these circles lies on the conductor itself. The direction of these field lines can be determined using the Right-Hand Thumb Rule.

(B) An electromagnet is typically made by winding a coil of insulated copper wire around a core of soft iron.
Soft iron is used because it has high magnetic permeability and low retentivity.
This means it can be easily magnetized when current flows through the coil and easily demagnetized when the current is switched off,making it ideal for temporary magnets.

(B) When an electric current flows through a straight conductor,it produces a magnetic field around it.
According to the Right-Hand Thumb Rule,the magnetic field lines are in the form of concentric circles with the conductor at the center.
The plane of these circles is perpendicular to the straight conductor.

(B) The direction of the magnetic field produced by a straight current-carrying conductor can be determined using the $Right-Hand$ $Thumb$ $Rule$.
According to this rule,if you hold the current-carrying conductor in your right hand such that your thumb points in the direction of the current,then your fingers wrapped around the conductor will point in the direction of the magnetic field lines.

(C) When current flows through a circular conductor,the magnetic field lines near the wire are circular. As we move towards the center of the circular loop,the circles become larger and larger. At the exact center of the circular loop,the magnetic field lines appear as straight lines.

(B) solenoid is defined as a cylindrical coil of many tightly wound turns of insulated copper wire,where the length of the coil is significantly greater than its diameter. When an electric current flows through it,it produces a magnetic field similar to that of a bar magnet.

(D) The magnetic field produced by a current-carrying solenoid depends on the following factors:
$1$. The magnitude of the current flowing through the solenoid: The magnetic field strength is directly proportional to the current.
$2$. The number of turns in the solenoid: The magnetic field strength is directly proportional to the number of turns per unit length.
$3$. The nature of the core material: If a soft iron rod is placed inside the solenoid,it acts as an electromagnet,significantly increasing the magnetic field strength compared to an air core.

(B) The strength $(B)$ of the magnetic field at a point near a current-carrying wire is directly proportional to the strength $(I)$ of the electric current flowing through the wire.
Mathematically,this is expressed as $B \propto I$.
This means that as the magnitude of the electric current increases,the strength of the magnetic field produced around the wire also increases.

(A) To demonstrate that the magnetic field decreases with distance,place a magnetic compass near a current-carrying wire.
Observe the deflection of the compass needle.
As you move the compass slowly away from the wire,the deflection of the needle decreases.
This reduction in deflection indicates that the strength of the magnetic field produced by the electric current decreases as the distance from the wire increases.

(B) piece of magnetic material can be magnetised by placing it inside a current-carrying solenoid. The magnetic field produced by the solenoid aligns the magnetic domains within the material,thereby converting it into an electromagnet.

(B) The magnetic field produced inside a solenoid is strong and uniform.
When a soft iron rod is placed inside the solenoid,the magnetic field of the solenoid magnetises the soft iron.
This combination of a soft iron core and a current-carrying solenoid is known as an electromagnet.

(B) The right-hand thumb rule states that if you hold a current-carrying straight conductor in your right hand such that your thumb points in the direction of the current,then your fingers wrapped around the conductor will show the direction of the magnetic field lines.
Therefore,the thumb indicates the direction of the current.

(N/A) An electric current can be induced in a coil by changing the magnetic field associated with it. One common method is to move a permanent magnet towards or away from the coil. As the magnet moves,the magnetic flux linked with the coil changes,which induces an electromotive force $(EMF)$ and consequently an electric current in the coil according to Faraday's Law of Electromagnetic Induction.

(N/A) The strength of an electromagnet can be increased by:
$(i)$ Increasing the number of turns of the wire in the solenoid.
$(ii)$ Increasing the magnitude of the electric current flowing through the solenoid.

(N/A) $(i)$ $A$ current-carrying conductor produces a magnetic field around it. When a compass needle is brought near this conductor,the magnetic field of the conductor exerts a force on the magnetic needle,causing it to deflect.
$(ii)$ The strength of the magnetic field produced by a current-carrying conductor is directly proportional to the magnitude of the current flowing through it. Therefore,when the current in the conductor is increased,the magnetic field strength increases,which leads to a greater deflection of the compass needle.

(N/A) The left figure represents the magnetic field lines produced by a current-carrying circular loop near its center,where the field lines appear as straight lines.
$(b)$ The right figure represents uniform magnetic field lines,which are produced by a long current-carrying solenoid.

(N/A) The deflection of the compass needle increases. Reason: The strength of the magnetic field produced by a current-carrying wire is directly proportional to the magnitude of the electric current flowing through it.
$(b)$ The deflection of the compass needle decreases. Reason: The strength of the magnetic field produced by a current-carrying wire is inversely proportional to the distance from the wire.

(N/A) The magnetic field produced around a straight current-carrying conductor is in the form of concentric circles with the center lying on the straight conductor.
Experiment:
$1$. Take a copper wire $AB$ and pass it through a hole in a cardboard.
$2$. Connect the ends of the wire to a battery and a key in a series circuit.
$3$. Sprinkle some iron filings uniformly on the cardboard.
$4$. Switch on the key to allow current to flow and tap the cardboard gently.
$5$. You will observe that the iron filings arrange themselves in the form of concentric circles around the wire.
$6$. If you reverse the direction of the current by changing the battery polarity,the iron filings will still form concentric circles,but the direction of the magnetic field lines will be reversed.
Conclusion: The magnetic field lines around a straight current-carrying conductor are concentric circles centered on the conductor. The direction of the magnetic field depends on the direction of the electric current.

(N/A) $1$. Take a rectangular cardboard with two holes and pass a circular copper coil through it such that half of the coil is above the cardboard and half is below.
$2$. Connect the free ends of the coil to a battery,a resistor,and a plug key in a series circuit.
$3$. Sprinkle iron filings uniformly on the cardboard surface.
$4$. Close the key to allow current to flow through the coil.
$5$. Gently tap the cardboard. You will observe that the iron filings arrange themselves in the form of concentric circles around the points where the wire passes through the cardboard.
$6$. Near the wire,the magnetic field lines are circular. As we move towards the center of the coil,the circles become larger and larger.
$7$. At the center of the coil,the magnetic field lines appear as straight lines. This indicates that the magnetic field is uniform and perpendicular to the plane of the coil at the center.

(N/A) solenoid is a cylindrical coil of many tightly wound turns of insulated wires,where the length of the coil is generally much greater than its diameter.
When an electric current is passed through the solenoid,a magnetic field is produced around and inside it.
The magnetic field lines produced by the solenoid are similar to those of a bar magnet. Since the current in each circular turn of the solenoid flows in the same direction,the magnetic effects of individual turns add up.
As a result,one end of the solenoid acts as the North pole $(N)$ and the other end acts as the South pole $(S)$,similar to a bar magnet.
The figure below illustrates the magnetic field lines of a current-carrying solenoid:

(N/A) The strength of the magnetic field produced by a current-carrying solenoid depends on the following factors:
$(a)$ The number of turns in the coil: The magnetic field is directly proportional to the number of turns $(N)$.
$(b)$ The strength of the current: The magnetic field is directly proportional to the current $(I)$ flowing through the solenoid.
$(c)$ The nature of the core material: The magnetic field is significantly increased when a soft iron core is placed inside the solenoid,as it acts as an electromagnet.

(N/A) The figure shows a bar magnet and a helical coil of wire connected to a galvanometer.
When there is no relative motion between the bar magnet and the coil,as shown in part $(a)$,the galvanometer shows zero deflection,indicating no current is flowing.
However,when the magnet moves toward the coil,as in part $(b)$,an induced current is generated in the coil.
As the magnet approaches,the magnetic field lines passing through the coil increase,and this change in magnetic flux induces the current.
When the magnet moves away from the coil,a current is also induced,but its direction is reversed because the magnetic flux through the coil decreases.
Thus,it is the change in the magnetic field (or magnetic flux) linked with the coil that generates the induced current.

(N/A) The existence of a magnetic field can be detected using a magnetic compass or by sprinkling iron filings on a cardboard sheet placed perpendicular to the plane of the loop. When current flows through the loop, the iron filings arrange themselves in concentric circles around the wire segments, and near the centre of the loop, the magnetic field lines appear as straight lines.
The direction of the magnetic field produced by a current-carrying circular loop is determined by the $Right-Hand$ $Thumb$ $Rule$. This rule states: "If you grasp the current-carrying conductor in your right hand such that your thumb points in the direction of the current, then the direction in which your fingers curl around the conductor gives the direction of the magnetic field lines."

(N/A) The magnetic field $B$ at the centre of a circular coil is given by the formula $B = \frac{\mu_0 NI}{2R}$,where $N$ is the number of turns,$I$ is the current,and $R$ is the radius.
$(i)$ The magnetic field is inversely proportional to the radius of the coil $(B \propto \frac{1}{R})$.
$(ii)$ The magnetic field is directly proportional to the number of turns in the coil $(B \propto N)$.
$(iii)$ The magnetic field is directly proportional to the current flowing through the coil $(B \propto I)$.

(N/A) The pattern of magnetic field lines around a current-carrying straight conductor consists of concentric circles centered on the conductor.
$(i)$ The strength of the magnetic field is directly proportional to the current flowing through the conductor. Therefore,the magnetic field increases with an increase in the current.
$(ii)$ The strength of the magnetic field is inversely proportional to the distance from the conductor. Therefore,the magnetic field decreases as the distance from the conductor increases.

(N/A) The pattern of magnetic field lines for a current-carrying circular loop is similar to that of a bar magnet,where the field lines are circular near the wire and become nearly parallel straight lines at the centre of the loop.
$(i)$ The magnetic field strength at the centre is given by $B = \frac{\mu_0 I}{2R}$. Since $B \propto I$,if the current $I$ is doubled,the magnetic field strength $B$ will also be doubled.
$(ii)$ Since $B \propto \frac{1}{R}$,if the radius $R$ is reduced to half $(R' = R/2)$,the new magnetic field strength $B'$ becomes $B' = \frac{\mu_0 I}{2(R/2)} = 2 \times \frac{\mu_0 I}{2R} = 2B$. Thus,the magnetic field strength will be doubled.

(N/A) The magnetic field lines produced by a current-carrying solenoid are similar to those of a bar magnet. Inside the solenoid,the field lines are parallel to the axis,indicating a uniform magnetic field. Outside,they form closed loops. The end from which the field lines emerge is the North pole $(N)$,and the end where they enter is the South pole $(S)$.

(N/A) The current flows in the east to west direction.
According to the Right-Hand Thumb Rule,if you point your thumb in the direction of the current (west),your fingers curl in the direction of the magnetic field.
For a point directly below the wire,the magnetic field lines point from north to south.
For a point directly above the wire,the magnetic field lines point from south to north.

(N/A) $(i)$
$(a)$ According to the right-hand thumb rule or by observing the direction of current flow,the face of the loop will behave as a North pole.
$(b)$ By applying the right-hand rule for a solenoid,the end $B$ will also behave as a North pole.
$(ii)$ The magnetic field at the centre of the loop is perpendicular to the plane of the loop,directed along the axis of the loop.

(N/A) solenoid is a coil of many turns of insulated copper wire wound closely in the form of a cylinder.
The magnetic field lines around a solenoid are as shown in the diagram below,where the field lines inside the solenoid are parallel to each other,indicating a uniform magnetic field.

(N/A) The deflection of the magnetic compass increases.
This happens because the strength of the magnetic field produced by a current-carrying straight conductor is directly proportional to the magnitude of the current flowing through it $(B \propto I)$.
Therefore,increasing the current increases the magnetic field strength,which exerts a greater force on the magnetic needle,resulting in a larger deflection.

(A) The first observation $(i)$ is wrong.
According to the Biot-Savart law or the properties of the magnetic field produced by a straight current-carrying conductor,the magnetic field strength $B$ is inversely proportional to the distance $r$ from the conductor $(B \propto 1/r)$.
Therefore,as the distance from the conductor increases,the strength of the magnetic field decreases.
Consequently,the degree of deflection of the magnetic compass needle should decrease,not increase,as it is moved away from the conductor.

(N/A) The deflection of the magnetic compass will increase.
This is because the strength of the magnetic field produced by a current-carrying straight conductor is directly proportional to the magnitude of the current flowing through it $(B \propto I)$.
Therefore,increasing the current increases the magnetic field strength,which exerts a greater force on the magnetic needle,resulting in a larger deflection.

(N/A) The strength of the magnetic field $(B)$ at the centre of a circular coil is inversely proportional to the radius $(r)$ of the coil. Mathematically, $B \propto 1/r$. Therefore, as the radius of the coil increases, the magnetic field strength at the centre decreases.
$(b)$ The strength of the magnetic field $(B)$ at the centre of a circular coil is directly proportional to the number of turns $(n)$ in the coil. Mathematically, $B \propto n$. Therefore, as the number of turns in the coil increases, the magnetic field strength at the centre increases.

(N/A) The magnetic field lines around a straight current-carrying conductor are concentric circles with the wire as the center. The direction of these lines can be determined using the Right-Hand Thumb Rule.
When the point where the magnetic field is to be determined is moved away from the straight wire,the strength of the magnetic field decreases.
Justification: The magnitude of the magnetic field $(B)$ produced by a straight current-carrying wire at a distance $(r)$ is inversely proportional to the distance from the wire,expressed as $B \propto 1/r$. Therefore,as the distance $(r)$ increases,the magnetic field strength $(B)$ decreases. This can be experimentally verified by observing the deflection of a compass needle,which decreases as it is moved further away from the wire.