# NCERT Solutions for Class 10 Science Chapter 13: Magnetic Effects of Electric Current Notes

In this section, you will get NCERT Class 10 Science Chapter 13 Magnetic effect of electric current notes. These notes are very useful from the examination point of view.

## Magnetic Effects of Electric Current Class 10 Science Notes

These notes have been prepared by the subject experts who have a teaching experience of more than 10 years. These notes will help you in NCERT and CBSE exams.

### Why does a compass needle get deflected when brought near a bar magnet?

A compass needle is a small magnet and has a magnetic field around it. When it is brought near a bar magnet, its field interacts with the magnetic field of the bar magnet which in turn leads to its deflection.

### Draw magnetic field lines around a bar magnet.

The magnetic field lines around a bar magnet are shown below.

### List the properties of magnetic lines of force.

A magnetic line of force is an imaginary line followed by the North of a magnetic needle, when allowed to do so in a magnetic field. Drawing these lines is a way of representing magnetic field.

Some of the important properties of magnetic lines of force are given below:

1. Outside the magnet, these lines are oriented North pole to South pole. Inside the magnet, they are oriented from South pole to North pole.
2. They form closed loops.
3. They do not intersect with each other.
4. The direction of magnetic field at any point can be found by drawing a tangent to the magnetic field line at that point.
5. The density of magnetic field lines shows the strength of the magnetic field.

### Why don’t two magnetic lines of force intersect with each other?

Two magnetic lines of force do not intersect with each other because if they did so, then there will be two directions of magnetic field at the point of their intersection. Which is impossible.

### The magnetic field in a given region is uniform. Draw a diagram to represent it.

The strength of magnetic field in any region is determined by the density of the magnetic field lines in that region. A uniform magnetic field is represented by a set of parallel and equidistant lines, as shown below;

### The magnetic field inside a long straight solenoid carrying current

1. is zero.
2. decreases as we move towards its ends.
3. increases as we move towards its ends.
4. is the same at all points.

The correct option is (4). The magnetic field lines inside a long straight solenoid carrying current exist in the form of straight, parallel and equidistant lines, representing a uniform magnetic field.

### Which of the following property of a proton can change while it movesfreely in a magnetic field? (There may be more than one correct answer.)

1. Mass
2. Speed
3. Velocity
4. Momentum.

Only (3) and (4) are correct.

Mass of the charge will not move in such non-relativistic conditions.

In addition, the work done by the magnetic force on a charge moving in a plane perpendicular to it is zero. So kinetic energy of the charge will not change, which in turn means that the speed will also not change.

The force will change the direction of the motion of the charge. It means the velocity will change. When velocity changes,linear momentum will also change.

### A positively-charged particle (alpha particle) projected towards west is deflected towards north by a magnetic field. The direction of magnetic field is:

The direction of magnetic field here can be determined using Fleming’s Left hand rule.

When we stretch the central finger towards West (in the direction of the motion of positive charge), and the thumb towards North (in the direction of the force experienced by the charge), then the fore finger points upwards.

Since the forefinger gives us the direction of the magnetic field, hence magnetic field is directed upwards.

### State Fleming’s left-hand rule.

Flemings left hand rule, also called as Motor rule states that, “if you extend the thumb, forefinger and the central finger of your left hand in three mutually perpendicular directions, then if the forefinger points in the direction of Magnetic field (B), and the central finger points in the direction of current (I), then the thumb will point in the direction of the magnetic Force (F)”.

### Name two safety measures commonly used in electric circuits and appliances.

The two safety measures commonly used in electric circuits and appliances are:

1. Electric fuse: it is an important circuit element that prevents the heavy flow of electric current in a circuit. Whenever, electric current passing through it exceeds the tolerable limit, it melts, thereby cutting the supply to the rest of the circuit. In this way, it saves the circuits from overloading and short circuiting.
2. Proper earthing: In earthing, we connect the metallic body of an electric appliance to the earth through a wire. It prevents us from electric shocks by sending the leakage current to the earth.

### What precaution should be taken to avoid the overloading of domestic electric circuits?

To avoid the overloading of domestic circuits, following precautions should be taken;

1. avoid using too many electric appliances at a time.
2. always use electric fuses/MCBs to ensure that the supply is cut, as and when the overloading is about to happen.
3. avoid plugging in too many devices in the same socket.

### List two methods of producing magnetic fields.

The two methods of producing magnetic fields are;

1. using a bar magnet.
2. using an electric current carrying solenoid.

### How does a solenoid behave like a magnet? Can you determine the north and south poles of a current–carrying solenoid with the help of a bar magnet? Explain.

A current carrying solenoid behaves like a magnet in the following manner;

1. the magnetic field produced by it is similar to the field produced by a bar magnet.
2. it behaves like a magnetic dipole, with the face having current in clockwise direction acting as the South pole and the face having current in anti-clockwise direction acting as the North pole.

We can determine the North and the South poles of a current carrying solenoid with the help of a bar magnet as follows;

1. bring the North pole of a bar magnet towards one end of the solenoid.
2. if it gets repelled, then this end of the solenoid is its North pole, and in the other case, it is the its South pole.

### When is the force experienced by a current–carrying conductor placed in a magnetic field largest?

The force experienced by a current carrying conductor placed in a magnetic field is largest when it is perpendicular to the direction of the magnetic field.

Reason: The force (F) experienced by a current carrying conductor placed in a magnetic field is given by:

F = BIL sinθ

Where I= current flowing through the conductor, B = strength of magnetic field, L= length of conductor in the magnetic field and θ= angle between the length of the conductor and the magnetic field.

Clearly, F is maximum, if θ=90 degree.

### State the rule to determine the direction of a (i) magnetic field produced around a straight conductor-carrying current, (ii) force experienced by a current-carrying straight conductor placed in a magnetic field which is perpendicular to it.

The rule that is used to determine the direction of magnetic field around a straight conductor carrying current is Right Hand Thumb rule. This rule states that if you place the thumb of your right hand in the direction of the current, then the direction in which your fingers curl is the direction of magnetic field around that conductor.

The rule that is used to determine the direction of force experienced by a current-carrying straight conductor placed in a magnetic field which is perpendicular to it is Fleming’s left hand rule. This rule states that “if you extend the thumb, forefinger and the central finger of your left hand in three mutually perpendicular directions, then if the forefinger points in the direction of Magnetic field (B), and the central finger points in the direction of current (I), then the thumb will point in the direction of the magnetic Force (F)”.

### When does an electric short circuit occur?

An electric short circuit occurs when a live wire directly touches a neutral wire. This direct connection provides a very low resistance path for the current to flow. Owing to this low resistance path, a heavy current flows through the wires, which heats them up to a dangerously high level making short circuits a main cause of domestic fires.

The main reasons behind the short circuit are;

2. using faulty electric appliances.
3. loose connections.

### What is the function of an earth wire? Why is it necessary to earth metallic appliances?

The function of an earth wire is to transfer leakage current to earth. The earth wire is connected to the metal body of a metallic appliance on one side and to the earth on the other side. Whenever the live wire touches the metallic body, the earth wire carries the current coming from that wire to the earth.

It is necessary to earth metallic appliances to prevent us from getting electric shocks.

Also Check: Light Reflection and Refraction Class 10 notes.

## MCQs On Magnetic Effects Of Electric Current

1. Oerested
2. Maxwell
3. Fleming
4. None

Oerested Port

### The magnetic field lines around a straight current carrying conductor exist in the form of;

1. concentric squares
2. concentric circles
3. concentric spheres
4. straight lines

Concentric circles

1. B/Qv Sinθ
2. BQV Sin θ
3. B/Qv Cosθ
4. BQv Cosθ

BQv sinθ

### A charge placed at rest in a magnetic field experiences;

1. No force
2. Some force
3. Some torque
4. All of the above

No force

### In Fleming’s left hand rule, the thumb, fore finger and the central finger, respectively represent;

1. Force on conductor, Magnetic field and current.
2. Force on conductor, Current and Magnetic field.
3. Magnetic field, current and Force on conductor.
4. None of the above

Force on conductor, Magnetic field and current.

Also Check: Class 10 history The rise of nationalism in Europe notes pdf.

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