CBSE Class 8 Science Revision Notes Chapter 14

Class 8 Science Revision Notes Chapter 14

CBSE Class 8 Science Revision Notes Chapter 14 – Chemical Effects of Electric Current 

Extramarks is a platform that provides NCERT solutions, notes, and other sources of study material. The Class 8 Science Chapter 14 Notes curated by subject matter experts at Extramarks will help students prepare the chapter for the exams. These notes are designed according to the recent CBSE Syllabus and curriculum.

Class 8 Chapter 14 Science Notes will provide a detailed understanding of the topics. Students who are looking for accurate and reliable guides can refer to the materials on the Extramarks website to prepare and improve their marks in exams.

Revision Notes for CBSE Class 8 Science Chapter 14

Access Class 8 Science Chapter 14 – Chemical Effects of Electric Current Notes 

Conductors and Insulators:

  1. The ease with which current can flow in a material is known as electrical conductivity.
  1. Materials through which the current cannot flow easily are said to be poor conductors of electricity. In other words, they have a very low value for electrical conductivity. Generally, non-metals are poor conductors of electricity.
  1. Materials that provide easy current flow are referred to as good electrical conductors. Metals and graphite have high electrical conductivity values when they are solids. They are thought to be effective electrical conductors.

Liquid Conductors:

  1. Some liquids can also conduct electricity just like solids. Distilled or pure water is a poor conductor of electricity but when some impurities like salts, bases, or acids are dissolved in it, it becomes a good conductor of electricity.
  2. Electrolytes are chemicals that, when dissolved in water, operate as a conductor of electricity. A few electrolyte examples are salts, bases, and acids. These compounds are produced by the compounding of two ions with opposite charges. The atoms or molecules that carry either a positive or negative charge with them are called ions. They are dissociated into their respective ions which become free to conduct electricity when they are dissolved in suitable solvents such as water.
  3. When certain substances such as acids, bases, and salts are dissolved in water, the water becomes a conductor of electricity. This leads to several chemical changes, for example, the colour of the solution may change or form bubbles at the electrodes due to the evolution of gases. This process is known as the chemical effects of electric current.


A chemical change is observed i.e. the electrolytes are dissociated into their constituent ions whenever current is passed through an electrolytic solution. This process is known as electrolysis.

For electrolysis to occur, a setup known as an electrolytic cell is needed. This cell contains electrodes which are mostly metal rods; they are dipped inside an acidic, salt or basic solution to complete a circuit that contains liquid conductors. These electrodes are connected to a switch in between and a battery which has both positively and negatively charged terminals. Based on the terminal an electrode is connected to, it is classified either as a cathode (when connected to a negative terminal) or anode (when connected to a positive terminal).

Some Applications of Electrolysis:

  • Electrolysis is used in the purification and extraction of some metals. The process is known as electrorefining.
  • Electrolysis is also used in electroplating.


The process of coating material using electric current with a layer of any desired metal is known as electroplating.

In this process, the desired metal, which is to be deposited on the surface, is placed as an anode in the electrolytic cell, while the sample that has to be coated is placed as the cathode.

Uses of Electroplating:

  • Chromium is electroplated on bath taps, car parts, kitchen gas burners, etc.
  • Gold and silver are electroplated on some less expensive metals.
  • Tin is electroplated on iron because it is less reactive than iron.
  • Electroplating of zinc is done on iron to prevent it from corrosion.

Some Other Phenomenon of Current:

The filament of the light bulb heats up and begins to glow when a current is passed through it due to the heating effect of the electric current.

When a compass is brought close to an electricity-conducting wire, the needle will deflect. This is known as the magnetic effect of electric current and reveals the presence of current in the wire.

Class 8 Science Revision Notes Chapter 14

Students can now easily access the Class 8 Science Notes Chapter 14 from Extramarks’ website for conceptual clarity of the chapter. These notes will make their study easier, without worrying about the need to prepare quality notes. Students can save time and focus better on their exam preparation.

Revision Notes For Class 8 Chapter 14 Chemical Effects of Electric Current Overview

Chapter 14 of Class 8 discusses terms relating to good conductors and bad conductors of electricity. Good conductors of electricity include metals like copper, whereas bad conductors include rubber and wood. This applies to liquids as well. When the water obtained from wells and other sources is salty, it makes them conduct electricity. On the contrary, since distilled or pure water does not contain dissolved salts, it is a poor conductor of electricity.

Chemical Effects of Electric Current 

When current is passed through chemical solutions, a chemical reaction takes place. Some of the chemical effects which take place during a chemical reaction are:

  • Gas bubbles are released at electrodes.
  • Deposition of metals at electrodes.
  • Change in the solution’s colour.


Electrolysis occurs when an electric current is conducted through ionic chemicals, causing them to decompose into simpler substances.


Conductors are substances or materials through which an electric current can pass easily. Examples include copper and aluminium.


These are also known as bad conductors. Insulators are the materials through which an electric current does not pass quickly. Examples include rubber and plastic.

Electric Circuit:

An electric circuit is a path that a current takes in a closed-loop circuit. Electricity is conducted only when the switch is closed. However, when the switch is open, i.e., there is a break in the circuit’s path, no electricity is conducted.


An electric component named a tester is used for checking the presence of electric current in a circuit. It contains an LED bulb, which indicates the presence of an electric current.

Conducting Liquids:

If salts are dissolved in liquids, they conduct electricity. The majority of the liquids that are conductors of electricity are solutions of acids, bases, or salts.

Acids, Bases, and Salts:

Bases and acids are usually good conductors of electricity since they contain ions. They dissociate to form ions when dissolved in a solution.

Electricity Conduction in Water:

Water conducts electricity only when acids, bases, or salts are dissolved in it, and a potential difference is applied across it.

Electrodes and Electrolyte:

An electrode is a conductor immersed in a solution, with its ends connected to a battery, forming a complete circuit. An electrode is mainly of two types: cathode (+) and anode (-).

When an electric current is passed through an electrode, it dissociates and submerges in a solution known as an electrolyte.

An electrochemical cell comprises three things: electrodes, an electrolyte, and a battery.

FAQs (Frequently Asked Questions)

1. Discuss electroplating and its applications.

The process of deposition of a desired layer of metal on another material with the help of electricity is called electroplating. Some of its applications are as follows:

  • Bathtub faucets, auto parts, gas range burners, and other items have chromium electroplating.
  • Gold and silver are electroplated on less expensive metals.
  • Tin is electroplated on iron because it is less reactive than iron.
  • To stop iron from corroding, zinc is electroplated onto it.

2. Define anions and cations.

The negatively charged ions are called anions, whereas the positively charged ions are called cations.

3. Discuss the purification of metals.

Purification of metals is an application of the chemical effects of current. It is done using electrolysis in which a metal is purified by separating it from its impurities. For doing so, the impure metal is first dipped in the solution in the form of an anode. Electrolysis breaks it down and deposits it on the cathode in the purified form. For instance, metals like copper, zinc, etc. are purified using this method.