February 15, 2022

# Class 10 Science Chapter 13 Magnetic Effects of Electric Current

In our last chapter, we learned a great deal about electricity. We saw what are the heating effects of electric current and various other things. In class 10 science chapter 13 magnetic effects of electric current, we will learn the various magnetic effects caused due to electric current.

By now, after doing so many experiments, one thing is clear electricity and magnetism are somehow linked to each other. They have some kind of relationship. In this chapter, we will learn about magnetic fields and electromagnetic effects. Other topics like electric motors, electric generators, etc. will also be discussed in detail.

## Class 10 Science Chapter 13 Magnetic Effects of Electric Current

Before moving on, let’s talk a bit about Hans Christian Oersted. He was one of the most prominent scientists of the 19th century. He was the first one to prove that electricity and magnetism are related. His research laid down the foundation for advanced technologies like tv, radio, fiber optics, etc.

# 13.1 — Magnetic field and field lines

A magnet exerts its influence in the region surrounding it, and the region up to which the force of the magnet can be detected is called the magnetic field of that magnet. A magnetic field has both direction and magnitude. The direction of the magnetic field is the direction in which a north pole of the compass needle moves inside it.

Magnetic field lines:  These are imaginary lines that are drawn around the magnet (inside its magnetic field). These lines emerge from the north pole as the direction of the magnetic field is north, and merge at the south pole.

# 13.2 — Magnetic field due to a current-carrying conductor

If you are following the activities that are given in the NCERT, then you know that electric current through a metallic conductor produces a magnetic field around. Now, to find the direction of the field that is produced, we must repeat activity 13.1 given in the syllabus book but this time in a different manner (refer to NCERT book to do the activity).

13.2.1 — magnetic field due to a current through a straight conductor

This part of class 10 science chapter 13 magnetic effects of electric current teaches what happens to the magnetic field when current flows through a straight conductor. After doing the activity given in the book, we come to the conclusion that the concentric circles representing the magnetic field around a current-carrying straight wire become larger as we move away from it.

13.2.2 — Right-hand thumb rule

There is a much easier way to find the direction of the field lines of the magnetic field. We use the right-hand thumb rule to do so. Imagine that you are holding a current-carrying straight conductor in your right hand in such a way that your thumb is pointing towards the direction of the current. This way your fingers will wrap around the conductor in the direction of the field lines of the magnetic field.

### Class 10 Science Chapter 13 Magnetic Effects of Electric Current

13.2.3 — Magnetic field due to a current through a circular loop

If a circular coil has ‘n’ turns then the magnetic field produced by it will be n times as large as that produced by a single turn. This is because the current in each circular turn has the same direction, and the field due to each turn then just adds up.

13.2.4 — Magnetic field due to a current in a solenoid

The solenoid is a cylinder-shaped device in which a coil of many circular turns of insulated copper wire is wrapped closely. The solenoid can be used to make an electromagnet, to do so one needs to place a magnetic material like soft iron inside the coil. A strong magnetic field that will be produced inside the solenoid will magnetize it.

# 13.3 — Force on a current-carrying conductor in a magnetic field

We know that electric current produces a magnetic field when flowing through a conductor, and this field exerts a force on the magnet that comes in the vicinity of that conductor through which the current is flowing. The magnet also exerts equal and opposite force on the conductor.

The direction of the force on the conductor depends on the direction of the current and magnetic field. When the direction of current is at right angles to the direction of the magnetic field, the magnitude of the force is the highest.

This part of class 10 science chapter 13 magnetic effects of electric current talks about Fleming’s left-hand rule, following which one can easily find the direction of the force on the conductor when the direction of current is at right angles.

According to Fleming’s left-hand rule, stretch the thumb, forefinger, and middle finger of your left hand such that they are mutually perpendicular.  This way, the direction in which your first finger is pointing will be the direction of the magnetic field, the second finger will give the direction of the current, and the thumb will point towards the direction of force acting on the conductor.

### Class 10 Science Chapter 13 Magnetic Effects of Electric Current

So far we have covered almost half of the topics in class 10 science chapter 13 magnetic effects of electric current. From here on, we will learn how do different devices like electric motors and generators work in context with electricity and magnetism.

# 13.4 — Electric motor

As you may already know an electric motor is a rotating device. This device converts electrical energy into mechanical energy. One can find the complete working of an electric motor in the NCERT book.

# 13.5 — Electromagnetic induction

This process by which a changing magnetic field in a conductor induces a current in another conductor is called electromagnetic induction. Michael Faraday first discovered electromagnetic induction in 1831. He discovered how a  moving manner can be used to generate electric current.

# 13.6 — Electric generator

An electric generator is a device or machine which is used to produce electricity. The generator uses mechanical energy to rotate a conductor in a magnetic field to produce electricity.

AC: The current that changes direction after equal intervals of time is called AC or an alternating current. All modern-day power stations produce alternating current. In India, the AC changes its direction after every 1/100 second which means that the frequency of AC is 50 Hz. In AC, the loss of electric power when transmitting over long distances is much lower as compared to DC.

DC: The current that does not change its direction and flows in the same direction is called direct current or DC.

# 13.7 — Domestic Electric circuits

This is the final topic of class 10 science chapter 13 magnetic effects of electric current. This is an important topic not just from an exam point but also from a real-life perspective. It gives a general idea of how the electricity from power stations is transmitted to our houses and other important aspects, like how the short circuit happens.

• The electricity supply is done through overhead electric poles or by underground cables.
• There are two wires involved in this process, one is called live wire or positive, and the other one is called neutral wire or negative.
• The positive wire is usually covered with a red insulation cover, while the negative wire is covered with a black insulation cover.
• The potential difference between these wires is 220 V in India.