Introduction
Our ancestors relied on fire for light, warmth, and cooking. Today at the flick of a switch, turn off a knob, or the push of a button we've instant power. This is possible because of the electric current. It is one of the important discoveries that helped us revolutionize the way we live. From the time we wake up till the time we sleep at night, our life is dependent on electricity. From the television that you simply watch to the toaster that you use to toast bread, all run on current. Besides playing a serious part in reception, electricity also plays a crucial role in industries, transportation, and communication. In this article, let us learn more about this important resource that we are highly dependent on.
What is Electric Current?
Electric Current is the rate of flow of electrons during a conductor. The SI Unit of electrical current is the Ampere. Electrons are minute particles that exist within the molecular structure of a substance. Sometimes, these electrons are tightly held and other times they are loosely held. When electrons are loosely held by the nucleus, they are able to travel freely within the limits of the body. Electrons are negatively charged particles hence when they move a number of charges moves and we call this movement of electrons as electric current. It should be noted that the amount of electrons that are ready to move governs the power of a specific substance to conduct electricity. Some materials allow current to maneuver better than others.
What is an Electromotive Force?
The motion of free electrons is normally haphazard. If a force acts on electrons to make them move in a particular direction, then up to some extent random motion of the electrons will be eliminated. An overall movement in one direction is achieved. The force that acts on the electrons to make them move in a certain direction is known as electromotive force and its quantity is known as voltage and is measured in volts.
Unit of Electric Current
The magnitude of electric current is measured in coulombs per second. The SI unit of electrical current is Ampere and is denoted by the letter A. Ampere is defined together as a coulomb of charge moving past some extent in one second. If there are 6.241 x 1018 electrons flowing through our frame one second then the electrical current flowing through its ‘One Ampere.’
The unit Ampere is widely used within electrical and electronic technology alongside multipliers like milliamp (0.001A), microamp (0.000001A), and so forth.
Visualizing Electric Current
To gain a deeper understanding of what an electrical current is and the way it behaves during a conductor, we will use the hookah analogy of electricity. Certainly, there are some limitations but they serve as a very basic illustration of current and current flow.
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We can compare the electrical current to the water flowing through the pipe. When pressure is applied to one end of the pipe, the water is forced to flow through the pipe in one direction. The amount of water flow is proportional to the pressure placed on the top. This pressure can be compared to the electromotive force.
Conventional Current Flow vs Electron Flow
There is tons of confusion around conventional current flow and electron flow. In this section, let us understand their differences.
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Conventional Current Flow
The conventional current flow works from positive to negative terminal and indicates the direction that positive charges would flow.
Electron Flow
The electron flow moves from a negative terminal to a positive terminal. Electrons are charged and are therefore interested in the positive terminal as unlike charges attract.
Properties of Electric Current
Electric current is a crucial quantity in electronic circuits. We have adapted electricity in our lives so much that it becomes impossible to imagine life without it. Therefore, it is important to know the properties of the electric current.
We know that current is the result of the flow of electrons. The work of moving the electron stream is understood as electricity. Electricity is often converted into other sorts of energy like heat, light energy, etc.
There are two sorts of current referred to as AC (AC) and DC (DC). The direct current can flow only in one direction, whereas the alternating direction flows in two directions. Direct current is not used as a primary energy source in industries. It is mostly used in low voltage applications such as charging batteries, aircraft applications, etc. Alternating current is used to operate appliances for both household and industrial and commercial use.
The electric current is measured in amperes. One ampere of current represents one coulomb of electrical charge moving past a selected point in one second.
The conventional direction of an electrical current is the direction during which a charge would move. Henceforth, the present flowing within the external circuit is directed far away from the positive terminal and toward the negative terminal of the battery.
Effects of Electric Current
When a current flows through a conductor, there are a number of signs which tell if a current is flowing or not. Following are the most prominent signs:
Heating Effect of Electric Current
When our clothes are crumpled, we use the iron box to make our clothes crisp and neat. On the principle of heating effect of current, iron boxes work. There are many such devices that employ the heating effect.
When an electrical current flows through a conductor, heat is generated within the conductor.
The heating effect is given by the following equation
H=I2RT
The Heating Effect depends on the Following Factor:
The time ‘t‘ for which the current flows. The longer the current flows in a conductor, the more heat is generated.
The electrical resistance of the conductor. Higher the resistance, the higher the heat produced.
The amount of current. The larger the amount of current the higher the heat produced.
If the present is little then the quantity of warmth generated is probably going to be very small and should not be noticed. However, if the present is larger then it's possible that a clear amount of warmth is generated.
Magnetic Effect of Electric Current
Another prominent effect that is noticeable when an electric current flows through the conductor is the build-up of the magnetic field. We can observe this when we place a compass close to a wire carrying a reasonably large direct current, the compass needle deflects. The magnetic flux generated by a current is put to good use during a number of areas. By winding a wire into a coil, the effects are often increased, and an electromagnet is often made.
Chemical Effect of Electric Current
When an electric current passes through a solution, the solution ionizes and breaks down into ions. This is because a reaction takes place when an electrical current passes through the answer. Depending on the nature of the solution and the electrodes used, the following effects can be observed in the solution:
Change in the color of the solution
Metallic deposits on the electrodes
A release of gas or production of bubbles in the solution
Electroplating and electrolysis are the applications of the chemical effect of electrical current.
Overview on Chapter 14 Class 7 Electric Current
Electric current and its effect is Chapter 14 of Class 7 science NCERT book, it is prescribed by the Central Board of secondary education and it deals with the concepts of Chemistry whose understanding is extremely important in order to study the complex concepts that are taught in higher classes.
The study material provided by the data on electric current and its effects discusses in-depth about electric charge, electric current, smaller units of electric current, the flow of current, electric potential and potential difference, sources of electricity, effects of electricity, heating effect, electromagnet, uses of electromagnets, electric bell, electric buzzer, chemical effect, electric circuit, connecting electric cells in series, connecting bulbs in parallel, conductors and insulators.
Students who may find it difficult to grasp these various terminologies that are used in Chemistry and Physics can refer to the notes provided by Vedantu on electric current and its effects; it is the base chapter that introduces various terminologies that are important for higher studies in Physics and as well as in Chemistry. These complex concepts are written in an extremely simplified language and are provided for students to help them get a comprehensive understanding of the many topics discussed.
Thales was a great scientist in 600 BC. He observed what happens when amber is rubbed with wool, it acquires the property of attracting hair, tiny bits of paper or cork. Much later in the 16th-century, Gilbert came across the same properties of various other substances like cat skin, sealing wax and wool etc. he gave this phenomenon a term called electricity.
A charge is the source of all electricity and electrical phenomena.
Subtopics studied in Chapter 14, Electric Current and its Effects are as Follows-
14.1 Symbols of Electronic Components
14.2 Heating Effect of Electric Current
14.3 Magnetic Effect of Electric Current
14.4 Electromagnet
14.5 Electric Bell
Key Points discussed in the Chapter-
An electric circuit is represented by a circuit diagram as representing electric components by symbols is the most convenient way of studying them.
The wire gets heated when an electric current is flowing through it. This is called the healing effect of electricity, it has various applications.
There are certain special materials used to make electrical fuses that aid in the prevention of fires and damage to electric appliances. The special materials which these wires are made of break when large electric currents are passed.
A wire behaves like a magnet when electric current flows through it.
An electromagnet is the current-carrying coil of an insulated wire which is wrapped around a piece of iron.
FAQs on Electric Current and Its Effects
1. What is meant by electric current as per the Class 7 syllabus?
Electric current is the flow of electric charges, typically electrons, through a material called a conductor. Think of it like water flowing through a pipe. For the current to flow, there must be a complete, unbroken path, which is known as a closed circuit. The standard unit for measuring electric current is the Ampere (A).
2. How are common electrical components represented using symbols in a circuit diagram?
In Physics, standard symbols are used to represent components in a circuit diagram to make them easy to draw and understand universally. The key symbols for Class 7 are:
- Electric Cell: A single long line (positive terminal) and a shorter, thicker parallel line (negative terminal).
- Battery: A combination of two or more cells connected in series.
- Switch (ON position): A closed path, showing the circuit is complete.
- Switch (OFF position): A broken path, showing the circuit is open.
- Bulb: A circle with a cross inside it.
- Connecting Wire: A simple straight line.
3. What is the heating effect of electric current? Give some examples from daily life.
The heating effect of electric current is the phenomenon where a conductor produces heat when an electric current flows through it. This happens because the material of the conductor offers resistance to the flow of current, converting electrical energy into heat energy. Common household appliances that work on this principle include an electric heater, geyser, electric iron, and a toaster.
4. What is the magnetic effect of electric current?
The magnetic effect of electric current describes how a wire behaves like a magnet when electricity passes through it. This was first observed by scientist Hans Christian Oersted, who noticed that a compass needle deflected when placed near a current-carrying wire. This principle is fundamental to the creation of electromagnets and the operation of devices like electric motors and bells.
5. What is the difference between an open circuit and a closed circuit?
The key difference lies in the continuity of the path for the current. A closed circuit is a complete and unbroken path that allows electric current to flow from the source, through the components (like a bulb), and back to the source, causing the appliance to work. An open circuit has a break or gap in it, such as an open switch, which interrupts the path and stops the flow of current.
6. How does an electromagnet work in an electric bell?
An electric bell uses an electromagnet to create its ringing sound. When you press the switch, the circuit is completed, and current flows through a wire coiled around an iron core, turning it into an electromagnet. This magnet attracts a soft iron strip attached to a hammer, causing the hammer to strike a gong. The movement of the strip also breaks the circuit, the electromagnet turns off, and the hammer springs back. This completes the circuit again, and the process repeats rapidly, producing a continuous ringing sound.
7. Why does a wire get hot when an electric current passes through it?
A wire gets hot due to a property called electrical resistance. Every material naturally resists the flow of electrons to some extent. As electrons are pushed through the wire, they collide with the atoms of the wire. These collisions transfer energy, which is released as heat. Materials with higher resistance produce more heat for the same amount of current.
8. What is an electric fuse and why is it an important safety device?
An electric fuse is a safety device designed to protect electrical circuits from damage caused by excessive current. It consists of a special wire with a very low melting point. If the current in the circuit suddenly increases to a dangerous level (an overload or short circuit), the fuse wire heats up rapidly, melts, and breaks the circuit. This stops the flow of electricity, preventing damage to appliances and reducing the risk of fire.
9. Can we use a normal copper wire as a replacement for a blown fuse? Why or why not?
No, you must never use a normal copper wire as a replacement for a fuse. A fuse is made from a special alloy with a specific, low melting point. A copper wire has a much higher melting point and is an excellent conductor. It would allow a dangerously high current to flow without melting, completely defeating the safety purpose of the fuse and creating a significant fire hazard.
