Class 10 Science Magnetic Effects of Electric Current

Q 1 :

A toaster of 4 kW is running in an existing circuit 110 volt that has a stream ranking of 4 A. Find the stream of electrons drawn by the toaster.

36.36 A
23.34 A
14.6 A
9.06 A

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(1)

The stream of electrons drawn by the toaster is 36.36 A.

$G i v e n, P = 4 k W, V = 110 V$

We know that, $P o w e r = V I = 110 \times I 4000 = 110 \times I I = 36.36 A$

Q 2 :

The most important safety method used for protecting home appliance from short circuiting on overloading is:

earthing
use of fuse
use of stabilizers
use of fuse electric meter

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(2)

Use of fuse is most important safety method protecting home appliances from overloading and short circuiting.

Q 3 :

If it takes 520 turns to make a solenoid that is 40 cm long with a radius of 1.2 m that carries a current of 6 A, then determine the magnetic field inside the solenoid

$7.2 \times 10^{- 3} T$
$9.8 \times 10^{- 3} T$
$8.4 \times 10^{- 4} T$
$10.2 \times 10^{- 4} T$

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(2)

Given,
I=6 A, L=40 cm=0.4 m, r=1.2 m, N=520

We know that, $B = \frac{μ_{0} N I}{L}$

On substituting the values in above formula:

$B = \frac{(4 π \times 10^{- 7} \times 520 \times 6)}{0.4} = \frac{(4 \times 3.14 \times 10^{- 7} \times 520 \times 6)}{0.4} = 97968 \times 10^{- 7} = 9.8 \times 10^{- 3} T$

The magnetic field inside the solenoid is

$B = 9.8 \times 10^{- 3} T$

Q 4 :

A 3 pin mains plug is fitted to the cable for a 1 kW electric kettle to be used on a 250 V a.c. supply which of the following statements is not correct?

The fuse should be fitted in the live wire.
A 13 A fuse is the most appropriate value to use.
The neutral wire is coloured black.
The green wire should be connected to the earth pin.

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(2)

$P = 1 k W = 1000 W, V = 250 V C u r r e n t, I = P / V = 1000 / 250 = 4 A $

Because current drawn is 4 A, a fuse of 13 A cannot be considered the most appropriate.

Q 5 :

The strength of an electromagnet after the limit cannot be increased by increasing the current through the solenoid. What is the reason behind this phenomenon?

Electrons start to corrode the solenoid.
Voltage through the solenoid gradually starts to decrease.
Resistance of the solenoid increases.
Current flowing through the solenoid is saturated.

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(4)

The strength of an electromagnet after the limit cannot be increased by increasing the current through the solenoid because current flowing through the solenoid is saturated.

Q 6 :

Two wires are placed in parallel; repulsion force and current in these two wires are $i_{1} a n d i_{2}$ respectively. What will be a force if the current is doubled in each wire?

2F
F/2
2F/4
4F

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(4)

If the current is doubled in each wire the force will be 4F. This can be explained as follows:

We know that the force of repulsion per unit length between two wires carrying current in opposite direction is:

$\frac{F}{l} = \frac{μ_{0} i_{1} i_{2}}{2 π d}$

Thus, when both $i_{1} a n d i_{2}$ are doubled, the force between them becomes four times.

Q 7 :

$H_{1} a n d H_{2}$ are heats produced by two copper wires having the same length and different diameters when they are connected in series and parallel respectively. From the above, we infer what of the following?

$H_{1} > H_{2}$
$H_{1} < H_{2}$
$H_{1} = H_{2}$
$H_{1} \neq H_{2}$

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(1)

When wires are connected in series, $R_{s} = R_{1} + R_{2}$

In parallel,

$R_{p} = \frac{R_{1} R_{2}}{R_{1} + R_{2}} : R_{s} > R_{p} : H_{2} < H_{1} [H \propto R]$

Then $H_{1} > H_{2}$

Q 8 :

The strength of magnetic field inside a long current carrying straight solenoid is:

more at the ends than at the centre.
minimum in the middle.
uniform at all points.
found to increase from one end to the other.

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(3)

Inside the solenoid, magnetic field lines are straight. This indicates strong magnetic field. Hence, magnetic field is uniform at all points inside the solenoid.

Q 9 :

Pick out the incorrect statement about magnetic lines of force.

Magnetic lines of force start from the North Pole and end on the South Pole.
No two magnetic lines of force can intersect each other.
Magnetic lines of force are far away from each other at the poles.
Magnetic lines of force are closed continuous curves.

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(3)

Magnetic lines of forces are closed continuous curves. They are nearer to each other at the point where magnetic field is strongest and far from each other where magnetic field is weak. At poles, magnetic lines of forces are nearest to each other because magnetic field is strongest at the pole.

No two magnetic lines of forces intersect with each other. At the point of intersection, the compass needle would point towards two directions, which is not possible.

They are continuous, forming closed loops without beginning or end, which start from the north pole and end at the south pole. Hence, statement (c), i.e., Magnetic lines of force are far away from each other at the poles is the incorrect statement.

Q 10 :

Strength of the magnetic field at a point in the space surrounding the magnet is measured by:

thickness of the magnet.
number of lines crossing a given point.
resistance of it.
length of the magnet.

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(2)

The strength of the magnetic field at a point in the space surrounding the magnet is measured by number of lines crossing a given point.

Q 11 :

The magnetic field strength of a solenoid can be increased by inserting:

a wooden piece into it.
an iron piece into it.
a glass piece into it.
paper roll into it.

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(2)

When a piece of soft iron is inserted inside a solenoid, then the strength of the magnetic field increases because the iron gets magnetized due to magnetic induction. This combination of the solenoid and the soft iron core so formed is called an electromagnet.

Q 12 :

The magnetic field inside the solenoid is:

non-uniform
variable
same at all points
zero

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(3)

The magnetic field inside the solenoid is same at all points. This is because the magnetic field lines inside the solenoid are in the form of parallel straight lines, which indicates that the magnetic field is uniform at all points inside the solenoid.

Q 13 :

The magnetic field lines inside a solenoid are in the form of:

Curved line
Circular lines
Zig-zag lines
Parallel straight lines

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(4)

The field lines inside the solenoid are in the form of parallel straight lines. This indicates that magnetic field is same at all points inside the solenoid.

Q 14 :

Which of the following correctly describes the magnetic field near a long straight wire?

The field consists of straight lines perpendicular to the wire
The field consists of straight lines parallel to the wire.
The field consists of radial lines originating from the wire.
The field consists of concentric circles centred on the wire.

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(4)

The magnetic field near a long straight wire consists of concentric circles whose centres lie on the wire. This can be confirmed by the Right-hand Thumb Rule.

According to this rule, if we put the thumb of our right hand in the direction of the current flow through the conductor/straight wire and encircle the wire with our fingers, then the direction of those fingers will correspond to the direction of the magnetic field.

Thus, the magnetic field lines will be in concentric circles around the conductor.

Q 15 :

Inside the magnet, the field lines move:

from South to North
from North to South
away from North pole
away from South poles

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(1)

Magnetic field is a vector quantity with both direction and magnitude. The direction of the magnetic field is taken as the direction in which a North pole of the compass needle moves inside it. The field lines emerge from the North pole and merge at the South pole, but inside the magnet, the direction of field lines is opposite, i.e., from South to North

Q 16 :

An electron moves with a speed v along positive direction of the x-axis. If a magnetic field B acts along the positive y-direction, then the force on the electron will act along:

x-axis
y-axis
−vez-direction
+vey-direction

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(3)

As the electron is moving in positive x-direction, according to Maxwell's right-hand thumb rule, the current is moving in negative x-direction and the magnetic field acts along positive y-direction.

By applying Fleming's left-hand rule, the thumb will be in negative z-direction, which is the direction of force.

Q 17 :

The force exerted on a current carrying wire placed in a magnetic field is zero when the angle between wire and the direction of magnetic field is:

$45^{\circ}$
$60^{\circ}$
$90^{\circ}$
$180^{\circ}$

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(4)

The force exerted on a current carrying wire placed in a magnetic field is zero when the angle between wire and the direction of magnetic field is $180^{\circ}$

A force is experienced by the current carrying wire in the presence of an external magnetic field. This can be expressed as:

$F = B I L \sin θ$

Where,

L is the length of the wire, I is the current, and $θ$ is the angle between the current and the magnetic field.

We know that $\sin 180^{\circ} = 0$ Therefore, the force exerted on a current carrying wire that is placed in a magnetic field is zero when the angle between the wire and the direction of magnetic field is $180^{\circ}$

Q 18 :

In the figure shown below, the point A and B are respectively:

North pole, South pole
South pole, North pole
North pole, North pole
South pole, South pole

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(2)

As magnetic lines of force start from the North pole and terminate at the South pole.

Q 19 :

The north pole of a long bar magnet was pushed slowly into a short solenoid connected to a galvanometer. The magnet was held stationary for a few seconds with the North pole in the middle of the solenoid and then withdrawn rapidly. The maximum deflection of the galvanometer was observed when the magnet was:

Moving towards the solenoid
Moving into the solenoid
At rest inside the solenoid
Moving out of the solenoid

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(4)

As due to electromagnetic induction.

Q 20 :

The magnetic field of the current was discovered by:

Maxwell
Fleming
Oersted
Faraday

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(3)

Hans Christian Oersted discovered that a compass needle got deflected when electric current passed through a metallic wire placed nearby.

Q 21 :

Three magnets A, B and C were dipped one by one in a heap of iron filings. It shows the amount of the iron filling sticking to them:

The strength of these magnets will be:

A>B>C
A < B < C
A=B=C
A < B > C

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(1)

Q 22 :

If we place the magnetic compass near the north pole of the magnet, which pole of the needle will point towards it?

North pole
South pole
Keep deflecting
None of these

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(2)

As like poles repel each other and unlike poles attract each other. Therefore, when the North pole of a bar magnet is brought near the compass, it gets deflected in the south direction.

Q 23 :

In the circuit shown below, what is direction of the current?

No current flowing
Anti-clock wise
Clock wise
Data insufficient

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(3)

If the current flows from North to South the compass needle will move towards the last.

Q 24 :

A proton enters a magnetic field at right angle to it, as shown below. The direction of force acting on the proton will be:

To the right
To the left
Out of the page
Into the page

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(4)

The proton enters a magnetic field at right-angle to it. Therefore, it will experience a force and the direction of force is calculated using Fleming’s Left-Hand Rule.

Q 25 :

A bar magnet is immersed in a heap of iron fillings and pulled out. The amount of iron filling clinging to the:

North pole is almost equal to the South pole
North pole is much more than the South Pole
North pole is almost less equal than the South pole
Magnet will be same all along its length

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(1)

As the maximum intensity of magnet is on the poles of the magnet.

Q 26 :

Rashita and her friends were decorating the class bulletin board. She accidentally dropped the box of stainless steel pins by mistake. She tried to collect the pins using a magnet. She could not succeed. Why?

They are not using the magnet in right direction
Steel pins are very heavy and cannot be lifted magnet
Steel pins are very long
Steel is not magnetic in nature

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(4)

As steel is not magnetic in nature, so it is not attracted by the magnet.

Q 27 :

If the current is passing through a straight conductor, then, the magnetic field lines around it forms a particular shape. That shape is:

Straight lines
Concentric circles
Concentric ellipse
Concentric parabolas

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(2)

When current passes through a straight conductor, then the magnetic field lines forms concentric circle around it.

Q 28 :

The figure given below shows the magnetic field produced by a currents carrying wire. Which of the diagram shows it correctly?

A
B
C
D

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(3)

As when current flows through current-carrying wire, then direction of magnetic field is calculated by right hand thumb rule.

Q 29 :

Consider the following statements and choose the correct are:

A magnet is an object which attracts pieces of iron, Nickel and cobalt
Magnetic effect of electric current means that an electric current flowing in a wire produces a magnetic field around it
The end of a freely suspended magnet which points towards the north direction is called the north pole of the magnet
All of the above

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(4)

(a) A magnet is an object which attracts pieces of iron, Nickel and cobalt.
(b) Magnetic effect of electric current means that an electric current flowing in a wire produces a magnetic field around it.
(c) The end of a freely suspended magnet which points towards the north direction is called the north pole of the magnet.

Q 30 :

A rectangular loop carrying a current I is situated near a long straight wire such that the wire is parallel to one of the sides of the loop and is in plane of the loop. If steady current I is created in wire as shown in figure below, then the loop:

Rotate about an axis parallel to the wire
Move towards the wire
Move away from the wire or towards right
Remains stationary

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(2)

$F o r c e F = \frac{μ_{0} 2 i_{1} i_{2}}{4 π r} ∴ F \propto \frac{1}{r} A s r_{1} < r_{2} ∴ F_{1} > F_{2} ∴ F_{net} = F_{1} - F_{2}$

(Directed towards the wire)

Topic Question Set

Q 1 :

A toaster of 4 kW is running in an existing circuit 110 volt that has a stream ranking of 4 A. Find the stream of electrons drawn by the toaster.

Q 2 :

The most important safety method used for protecting home appliance from short circuiting on overloading is:

Q 3 :

If it takes 520 turns to make a solenoid that is 40 cm long with a radius of 1.2 m that carries a current of 6 A, then determine the magnetic field inside the solenoid

Q 4 :

A 3 pin mains plug is fitted to the cable for a 1 kW electric kettle to be used on a 250 V a.c. supply which of the following statements is not correct?

Q 5 :

The strength of an electromagnet after the limit cannot be increased by increasing the current through the solenoid. What is the reason behind this phenomenon?

Q 6 :

Two wires are placed in parallel; repulsion force and current in these two wires are $i_{1} a n d i_{2}$ respectively. What will be a force if the current is doubled in each wire?

Q 7 :

$H_{1} a n d H_{2}$ are heats produced by two copper wires having the same length and different diameters when they are connected in series and parallel respectively. From the above, we infer what of the following?

Q 8 :

The strength of magnetic field inside a long current carrying straight solenoid is:

Q 9 :

Pick out the incorrect statement about magnetic lines of force.

Q 10 :

Strength of the magnetic field at a point in the space surrounding the magnet is measured by:

Q 11 :

The magnetic field strength of a solenoid can be increased by inserting:

Q 12 :

The magnetic field inside the solenoid is:

Q 13 :

The magnetic field lines inside a solenoid are in the form of:

Q 14 :

Which of the following correctly describes the magnetic field near a long straight wire?

Q 15 :

Inside the magnet, the field lines move:

Q 16 :

An electron moves with a speed v along positive direction of the x-axis. If a magnetic field B acts along the positive y-direction, then the force on the electron will act along:

Q 17 :

The force exerted on a current carrying wire placed in a magnetic field is zero when the angle between wire and the direction of magnetic field is:

Q 18 :

In the figure shown below, the point A and B are respectively:

Q 20 :

The magnetic field of the current was discovered by:

Q 21 :

Three magnets A, B and C were dipped one by one in a heap of iron filings. It shows the amount of the iron filling sticking to them:

The strength of these magnets will be:

Q 22 :

If we place the magnetic compass near the north pole of the magnet, which pole of the needle will point towards it?

Q 23 :

In the circuit shown below, what is direction of the current?

Q 24 :

A proton enters a magnetic field at right angle to it, as shown below. The direction of force acting on the proton will be:

Q 25 :

A bar magnet is immersed in a heap of iron fillings and pulled out. The amount of iron filling clinging to the:

Q 26 :

Rashita and her friends were decorating the class bulletin board. She accidentally dropped the box of stainless steel pins by mistake. She tried to collect the pins using a magnet. She could not succeed. Why?

Q 27 :

If the current is passing through a straight conductor, then, the magnetic field lines around it forms a particular shape. That shape is:

Q 28 :

The figure given below shows the magnetic field produced by a currents carrying wire. Which of the diagram shows it correctly?

Q 29 :

Consider the following statements and choose the correct are:

Q 30 :

A rectangular loop carrying a current I is situated near a long straight wire such that the wire is parallel to one of the sides of the loop and is in plane of the loop. If steady current I is created in wire as shown in figure below, then the loop:

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Topic Question Set

Q 1 : A toaster of 4 kW is running in an existing circuit 110 volt that has a stream ranking of 4 A. Find the stream of electrons drawn by the toaster.

Q 2 : The most important safety method used for protecting home appliance from short circuiting on overloading is:

Q 3 : If it takes 520 turns to make a solenoid that is 40 cm long with a radius of 1.2 m that carries a current of 6 A, then determine the magnetic field inside the solenoid

Q 4 : A 3 pin mains plug is fitted to the cable for a 1 kW electric kettle to be used on a 250 V a.c. supply which of the following statements is not correct?

Q 5 : The strength of an electromagnet after the limit cannot be increased by increasing the current through the solenoid. What is the reason behind this phenomenon?

Q 6 : Two wires are placed in parallel; repulsion force and current in these two wires are i1 and i2 respectively. What will be a force if the current is doubled in each wire?

Q 7 : H1 and H2 are heats produced by two copper wires having the same length and different diameters when they are connected in series and parallel respectively. From the above, we infer what of the following?

Q 8 : The strength of magnetic field inside a long current carrying straight solenoid is:

Q 9 : Pick out the incorrect statement about magnetic lines of force.

Q 10 : Strength of the magnetic field at a point in the space surrounding the magnet is measured by:

Q 11 : The magnetic field strength of a solenoid can be increased by inserting:

Q 12 : The magnetic field inside the solenoid is:

Q 13 : The magnetic field lines inside a solenoid are in the form of:

Q 14 : Which of the following correctly describes the magnetic field near a long straight wire?

Q 15 : Inside the magnet, the field lines move:

Q 16 : An electron moves with a speed v along positive direction of the x-axis. If a magnetic field B acts along the positive y-direction, then the force on the electron will act along:

Q 17 : The force exerted on a current carrying wire placed in a magnetic field is zero when the angle between wire and the direction of magnetic field is:

Q 18 : In the figure shown below, the point A and B are respectively:

Q 20 : The magnetic field of the current was discovered by:

Q 21 : Three magnets A, B and C were dipped one by one in a heap of iron filings. It shows the amount of the iron filling sticking to them: The strength of these magnets will be:

Q 22 : If we place the magnetic compass near the north pole of the magnet, which pole of the needle will point towards it?

Q 23 : In the circuit shown below, what is direction of the current?

Q 24 : A proton enters a magnetic field at right angle to it, as shown below. The direction of force acting on the proton will be:

Q 25 : A bar magnet is immersed in a heap of iron fillings and pulled out. The amount of iron filling clinging to the:

Q 26 : Rashita and her friends were decorating the class bulletin board. She accidentally dropped the box of stainless steel pins by mistake. She tried to collect the pins using a magnet. She could not succeed. Why?

Q 27 : If the current is passing through a straight conductor, then, the magnetic field lines around it forms a particular shape. That shape is:

Q 28 : The figure given below shows the magnetic field produced by a currents carrying wire. Which of the diagram shows it correctly?

Q 29 : Consider the following statements and choose the correct are:

Q 30 : A rectangular loop carrying a current I is situated near a long straight wire such that the wire is parallel to one of the sides of the loop and is in plane of the loop. If steady current I is created in wire as shown in figure below, then the loop:

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Q 1 :

A toaster of 4 kW is running in an existing circuit 110 volt that has a stream ranking of 4 A. Find the stream of electrons drawn by the toaster.

Q 2 :

The most important safety method used for protecting home appliance from short circuiting on overloading is:

Q 3 :

If it takes 520 turns to make a solenoid that is 40 cm long with a radius of 1.2 m that carries a current of 6 A, then determine the magnetic field inside the solenoid

Q 4 :

A 3 pin mains plug is fitted to the cable for a 1 kW electric kettle to be used on a 250 V a.c. supply which of the following statements is not correct?

Q 5 :

The strength of an electromagnet after the limit cannot be increased by increasing the current through the solenoid. What is the reason behind this phenomenon?

Q 6 :

Two wires are placed in parallel; repulsion force and current in these two wires are $i_{1} a n d i_{2}$ respectively. What will be a force if the current is doubled in each wire?

Q 7 :

$H_{1} a n d H_{2}$ are heats produced by two copper wires having the same length and different diameters when they are connected in series and parallel respectively. From the above, we infer what of the following?

Q 8 :

The strength of magnetic field inside a long current carrying straight solenoid is:

Q 9 :

Pick out the incorrect statement about magnetic lines of force.

Q 10 :

Strength of the magnetic field at a point in the space surrounding the magnet is measured by:

Q 11 :

The magnetic field strength of a solenoid can be increased by inserting:

Q 12 :

The magnetic field inside the solenoid is:

Q 13 :

The magnetic field lines inside a solenoid are in the form of:

Q 14 :

Which of the following correctly describes the magnetic field near a long straight wire?

Q 15 :

Inside the magnet, the field lines move:

Q 16 :

An electron moves with a speed v along positive direction of the x-axis. If a magnetic field B acts along the positive y-direction, then the force on the electron will act along:

Q 17 :

The force exerted on a current carrying wire placed in a magnetic field is zero when the angle between wire and the direction of magnetic field is:

Q 18 :

In the figure shown below, the point A and B are respectively:

Q 20 :

The magnetic field of the current was discovered by:

Q 21 :

Three magnets A, B and C were dipped one by one in a heap of iron filings. It shows the amount of the iron filling sticking to them:

The strength of these magnets will be:

Q 22 :

If we place the magnetic compass near the north pole of the magnet, which pole of the needle will point towards it?

Q 23 :

In the circuit shown below, what is direction of the current?

Q 24 :

A proton enters a magnetic field at right angle to it, as shown below. The direction of force acting on the proton will be:

Q 25 :

A bar magnet is immersed in a heap of iron fillings and pulled out. The amount of iron filling clinging to the:

Q 26 :

Rashita and her friends were decorating the class bulletin board. She accidentally dropped the box of stainless steel pins by mistake. She tried to collect the pins using a magnet. She could not succeed. Why?

Q 27 :

If the current is passing through a straight conductor, then, the magnetic field lines around it forms a particular shape. That shape is:

Q 28 :

The figure given below shows the magnetic field produced by a currents carrying wire. Which of the diagram shows it correctly?

Q 29 :

Consider the following statements and choose the correct are:

Q 30 :

A rectangular loop carrying a current I is situated near a long straight wire such that the wire is parallel to one of the sides of the loop and is in plane of the loop. If steady current I is created in wire as shown in figure below, then the loop: