A conductor is a substance that allows electric current to pass through it easily because it contains free electrons or ions. Metals like copper, aluminium and iron are good conductors. A metal wire used in electric circuits is a common example.

An insulator is a substance that does not allow electric current to pass through it easily. It has no free charge carriers. Examples include plastic, rubber, glass and dry wood. These are used as coverings on wires and plugs for safety.

This distinction is important because in this chapter we study chemical effects of electric current in liquids. Only those liquids that behave as conductors (contain ions) will show chemical changes when current passes through them. Insulating liquids like kerosene and oil will not allow enough current, so they do not show noticeable chemical effects of electric current. Therefore, knowing whether a substance is a conductor or insulator helps us choose the correct materials and liquids for experiments and applications such as electroplating.

Distilled water: Distilled water is obtained by boiling water and then condensing the steam. It is almost pure water and contains practically no dissolved salts. Because of the absence of ions, it is a poor conductor of electricity.

Tap water: Tap water contains various dissolved salts and minerals. These dissolved substances form ions (charged particles) in water, which can move and carry electric current. Therefore, tap water is a better conductor of electricity than distilled water.

Experiment to show the difference:

1. Set up a simple circuit with a battery, switch, LED (or bulb) and two clean electrodes.
2. Dip the electrodes in a beaker containing distilled water and switch on the current. The LED does not glow, showing poor conduction.
3. Now replace the distilled water with tap water without changing the rest of the circuit.
4. Switch on the circuit. The LED glows (even if faintly), indicating that tap water conducts electricity.

This experiment clearly proves that tap water is a conductor due to dissolved salts, while distilled water is almost an insulator.

To test whether a liquid conducts electricity, we can set up the following simple circuit:

1. Connect a battery, a switch and an LED in series using connecting wires.
2. Attach two conducting electrodes (e.g., graphite rods or metal nails) to the free ends of the wires.
3. Dip the electrodes into the given liquid contained in a beaker, ensuring they do not touch each other.
4. Switch on the circuit and observe the LED.

Observation: If the LED glows, current is passing through the liquid and it is a conductor. If it does not glow, the liquid is a poor conductor or an insulator.

Why LED is preferred over ordinary bulb:

• An ordinary filament bulb needs a comparatively large current to heat the filament enough to glow.
• Many liquids allow only a weak current to pass. This weak current is not sufficient to light up a bulb.
• An LED is very sensitive and can glow even with a small current. Therefore, it can detect weak conduction that a bulb cannot show.

Hence, an LED gives more reliable results in testing the conductivity of various liquids, especially weak electrolytes.

The magnetic effect of electric current can be used to detect the presence of current in a circuit as follows:

1. Take a small compass needle and place it near a coil of wire (few turns) connected in a circuit.
2. Connect a battery, switch, the coil and two electrodes in series.
3. Dip the electrodes into the liquid to be tested, ensuring they don’t touch each other.
4. Switch on the current and carefully observe the compass needle.

Observation:

• If the liquid conducts electricity, current flows through the coil.
• The coil then behaves like a magnet due to the magnetic effect of current.
• The compass needle gets deflected from its original north–south position.

Conclusion: The deflection of the compass needle is evidence that electric current is passing through the coil and therefore through the liquid. If there is no deflection, the liquid is not conducting or the current is too weak. This method is especially useful when even an LED does not glow clearly, but the magnetic effect can still be detected.

The chemical effect of electric current refers to the chemical changes produced in a conducting liquid (electrolyte) when electric current is passed through it. These changes occur due to the movement of ions and reactions at the electrodes.

Three observable changes are:

1. Formation of gas bubbles: Gas bubbles often appear at one or both electrodes. For example, when current is passed through water containing an acid or base, bubbles of hydrogen and oxygen may form at the electrodes. This shows that the liquid is decomposing and new substances (gases) are being formed.
2. Change in colour of the solution: Some solutions change colour when current is passed. This happens because ions are removed from or added to the solution. For example, in some experiments with coloured ionic solutions, the colour may fade or become deeper, indicating a chemical change.
3. Deposition of a metal or change in mass of electrodes: A metal may get deposited on one of the electrodes (usually the cathode). At the same time, the other electrode may get thinner as atoms leave it and go into the solution as ions. This is clearly seen in copper sulphate experiments where copper is deposited on the cathode.

These changes prove that electric current can cause chemical reactions in solutions, not just heating or magnetic effects.

Electrolyte: An electrolyte is a conducting liquid or solution that allows electric current to pass through it by the movement of ions. Examples: solutions of acids, bases and salts in water such as hydrochloric acid, sodium hydroxide and copper sulphate.

Electrode: Electrodes are conducting rods or plates (metal or graphite) dipped in the electrolyte and connected to the external circuit (battery).

Anode: The anode is the positive electrode connected to the positive terminal of the battery.

Cathode: The cathode is the negative electrode connected to the negative terminal of the battery.

Together, the electrolyte and the two electrodes form an electrolytic cell. When the circuit is completed, electric current enters the electrolyte through one electrode and leaves through the other. Ions in the electrolyte move towards the electrodes: positive ions move towards the cathode and negative ions move towards the anode, causing chemical changes in the system.

Procedure:

1. Take a beaker and fill it with copper sulphate (CuSO₄) solution prepared in water.
2. Clean two copper plates and dip them in the solution so that they stand parallel to each other. These act as electrodes.
3. Connect one copper plate to the positive terminal of a battery (anode) and the other to the negative terminal (cathode).
4. Allow the current to pass through the solution for about 15–20 minutes.
5. After some time, remove the electrodes and observe their surfaces carefully.

Observations:

• The cathode (negative electrode) gets coated with a reddish-brown layer of copper.
• The anode (positive electrode) becomes thinner or may have small pits on its surface.
• The blue colour of the copper sulphate solution does not change much during the experiment.

Conclusions:

• Copper ions (Cu²⁺) from the solution are deposited as copper metal on the cathode, showing that current causes chemical deposition.
• Copper atoms from the anode go into the solution as Cu²⁺ ions, making the anode thinner.
• Because the copper lost by the anode is almost equal to the copper gained by the cathode, the concentration of the solution remains nearly the same, so the blue colour does not change much.

This experiment clearly demonstrates the chemical effect of electric current and also forms the basis of the process of electroplating.

If iron electrodes are used in copper sulphate solution, the following changes can be observed:

• Copper from the copper sulphate solution may get deposited on the iron electrode connected as the cathode.
• The iron anode may gradually dissolve, and the solution may change colour over time due to formation of iron sulphate.

Reason:

• Iron is more reactive than copper. In addition to the electrolytic process, a chemical displacement reaction can occur:
  Fe + CuSO₄ → FeSO₄ + Cu
• As a result, copper is displaced from copper sulphate solution and gets deposited on the iron electrode, while iron goes into the solution as iron ions (Fe²⁺).
• This changes the composition and colour of the solution, showing a combined effect of chemical reactivity and electric current.

Hence, unlike the case with copper electrodes, the solution does not remain the same; it slowly changes due to both electrochemical and chemical reactions.

Electrolysis is the process in which an electric current is passed through a conducting liquid (electrolyte), causing it to undergo chemical decomposition. New substances are formed at the electrodes as a result of this process.

Role of ions in conduction:

• When salts, acids or bases dissolve in water, they split into positively and negatively charged particles called ions.
• Positive ions are called cations and negative ions are called anions.
• In the presence of a potential difference (battery), cations move towards the cathode and anions move towards the anode.
• As ions move through the solution and towards the electrodes, they carry electric charge, allowing current to flow through the electrolyte.
• At the electrodes, ions may gain or lose electrons and get converted into neutral atoms or molecules, causing chemical changes such as gas formation or metal deposition.

Therefore, ions are responsible for both conduction of electricity in liquids and the chemical effects observed during electrolysis.

Solutions of acids, bases and salts:

• When acids (like HCl), bases (like NaOH) and salts (like NaCl, CuSO₄) are dissolved in water, they dissociate into ions.
• Acids produce H⁺ ions, bases produce OH⁻ ions and salts produce both positive and negative ions.
• These ions move freely in the solution. Under the influence of electric potential, they move towards opposite electrodes, carrying charge and allowing current to pass.

Pure water:

• Pure or distilled water contains almost no dissolved salts or acids.
• Very few water molecules separate into ions, so the number of charge carriers is extremely small.
• Therefore, pure water is an almost non-conductor of electricity.

Kerosene and other oils:

• Kerosene and many oils are covalent compounds and do not form ions in the liquid state.
• In the absence of ions, these liquids cannot allow movement of charge under an electric field.
• Hence, they behave as insulators and do not conduct electricity.

Thus, the presence or absence of ions in a liquid decides whether it conducts electricity or not.

Electroplating is the process of depositing a thin layer of one metal over the surface of another metal object by passing electric current through an appropriate electrolyte.

Principle:

• When an electric current is passed through a solution of a metal salt (electrolyte), the metal ions in the solution move towards the electrode of opposite charge.
• At the cathode (negative electrode), positive metal ions gain electrons and get deposited as a thin metal layer.
• At the anode (positive electrode), atoms of the metal lose electrons, become ions and go into the solution.
• Thus, metal from the anode is transferred through the solution onto the cathode, coating it with a thin metal layer.

In an electrolytic cell used for electroplating:

• The object to be plated is connected as the cathode.
• The metal to be deposited is connected as the anode.
• The electrolyte is a solution of a salt of the metal to be deposited (e.g., copper sulphate for copper plating).

When the circuit is switched on, the desired metal gets deposited on the cathode, giving the object a uniform, thin coating of that metal.

To electroplate an iron key with copper, follow these steps:

1. Cleaning the key: Clean the iron key thoroughly using sandpaper or a suitable cleaning solution to remove rust, grease or dirt. This ensures proper sticking of the copper layer.
2. Setting up electrodes: Connect the cleaned iron key to the negative terminal of a battery; it acts as the cathode. Take a strip of copper metal and connect it to the positive terminal of the battery; it acts as the anode.
3. Preparing the electrolyte: Take a beaker containing a solution of copper sulphate (CuSO₄) in water. This solution serves as the electrolyte and provides Cu²⁺ ions.
4. Connecting the circuit: Dip both the copper strip and the iron key in the copper sulphate solution without letting them touch each other. Complete the circuit with wires, switch and the battery.
5. Passing current: Switch on the circuit and allow current to pass for some time (say 15–20 minutes).
6. Observation: After switching off the current, take out the key. You will see a reddish-brown layer of copper deposited on the key.

Role of each component:

• Iron key (cathode): Receives copper ions from the solution and gets coated with copper metal.
• Copper strip (anode): Supplies copper atoms, which go into the solution as Cu²⁺ ions, maintaining ion concentration.
• Copper sulphate solution (electrolyte): Provides copper ions for deposition and completes the circuit through ionic conduction.
• Battery: Drives the current through the circuit, enabling movement of ions and deposition of copper.

Four important uses of electroplating are:

1. Protection from corrosion: Iron objects, such as food cans, are electroplated with tin. Tin is less reactive than iron and does not rust easily. The thin tin layer prevents air and moisture from reaching iron, protecting it from corrosion and helping to keep food safe.
2. Improved appearance: Cheap metal jewellery and decorative items are electroplated with gold or silver. This gives them a bright, attractive appearance like real gold or silver, while the inner metal remains inexpensive.
3. Hard and wear-resistant surfaces: Parts of bicycles, motorcycles and cars are often electroplated with chromium. Chromium is hard, shiny and resistant to scratches and corrosion, so it provides a durable and attractive finish to these parts.
4. Saving expensive metals: In many cases, an object made entirely of a precious metal would be too costly. By electroplating a thin layer of the expensive metal (like gold, silver or chromium) onto a cheaper metal, we can obtain the required surface properties at lower cost, saving large amounts of precious metals.

Thus, electroplating has both protective and decorative uses and is economically very important in industry.

Electroplating is carefully controlled in industries for several reasons:

• Uniform thickness: A controlled current and time ensure that the deposited metal layer has even thickness. Uneven layers can peel off or wear out quickly.
• Cost control: Precious metals like gold, silver and chromium are expensive. By controlling the process, only the required thin layer is deposited, preventing wastage and reducing cost.
• Quality and performance: Correct thickness and good adhesion of the coating are necessary for proper protection against corrosion and for a good appearance. Poor control can lead to weak, porous coatings that do not serve their purpose.
• Safety and efficiency: Proper control of current, voltage and chemical concentration is important for safe operation of equipment and to avoid damage to the objects being plated.

If the process is not properly controlled:

• The coating may be too thick, increasing cost unnecessarily and causing cracking or peeling.
• The coating may be too thin, giving poor protection and wearing away quickly.
• The deposit may be uneven or rough, making the object look unattractive and affecting its function.
• Excessive current may cause overheating, gas formation and poor-quality deposits.

Therefore, industries use carefully monitored conditions and sometimes automatic control systems to get high quality, economical electroplating.

Experiments on chemical effects of electric current are done using only cells or small batteries because:

• Safety: Batteries provide low voltage and limited current, which are generally safe for students. On the other hand, mains supply (household electricity) has high voltage. Accidental contact with mains can cause serious electric shock, burns or even be fatal.
• Possibility of spillage: These experiments involve liquids (electrolytes) that can spill. If mains-operated equipment comes in contact with spilled liquids, it can cause short circuits and dangerous situations.
• Simple apparatus: Cells and batteries can be easily connected or disconnected using simple switches and wires. This helps students understand circuits clearly without the risk associated with complex mains connections.
• Control of current: Batteries provide a limited amount of current, which is sufficient to show chemical effects (like small gas bubbles or deposition) but not enough to cause major damage to the apparatus.

Therefore, to ensure the safety of students and equipment, only low-voltage batteries or dry cells are used in school experiments instead of mains electricity.

Four important precautions are:

1. Use low-voltage sources only: Always use cells or small batteries instead of mains electricity. This reduces the risk of electric shock and damage if something goes wrong.
2. Avoid touching the solution and electrodes when the circuit is on: Electric current passes through the liquid and electrodes. Touching them while the circuit is on can give an electric shock. Therefore, always switch off the current before adjusting the electrodes.
3. Keep the work area dry: Do not let water or electrolyte spill near the battery terminals or other electrical connections. Spilled liquids can cause short circuits and may give electric shocks if touched.
4. Handle chemicals carefully: Many electrolytes contain acids, bases or salts that can irritate the skin or eyes. Avoid touching them directly, do not taste them, and wash hands thoroughly after the experiment. Use protective equipment like gloves or goggles if needed and follow the teacher’s instructions.

Following these precautions ensures that experiments on chemical effects of current are carried out safely and effectively in the school laboratory.

The study of chemical effects of electric current is very useful because it explains many processes used in daily life and industry. Four examples are:

1. Electroplating: Learning about chemical effects helps us understand how a thin layer of one metal is deposited on another. This is widely used to protect metal objects from rust and to make jewellery and utensils more attractive.
2. Purification of metals: In industries, impure metals like copper are purified by passing current through a solution of their salts. Pure metal gets deposited on the cathode, while impurities are left behind. This process is based on chemical effects of electric current.
3. Electrolysis in chemical industries: Important substances like chlorine, hydrogen, sodium hydroxide and aluminium are produced using electrolysis. Understanding how current causes chemical changes helps us design such industrial processes.
4. Battery operation: Batteries themselves work due to chemical reactions that produce electricity. Studying chemical effects helps us understand how ions move and how chemical energy is converted to electrical energy inside a cell or battery.

Thus, knowledge of chemical effects of electric current connects classroom learning with real-life technologies and helps students appreciate the importance of science in everyday life.

The statement means that although many substances conduct electricity, only some of them undergo noticeable or useful chemical changes when current passes.

Examples:

• Metallic conductors: Metals like copper and aluminium are good conductors. When current passes through a metal wire, it produces heating effect and magnetic effect but usually no visible chemical change in the metal. Therefore, they are used mainly for conducting electricity, not for chemical changes.
• Electrolytes: Solutions of salts, acids and bases not only conduct electricity but also undergo chemical changes. For instance, when current passes through copper sulphate solution, copper is deposited on the cathode and the anode dissolves. This is a useful chemical effect used in electroplating and purification of metals.
• Non-electrolytic liquids: Liquids like kerosene and oil do not allow current to pass (they are insulators), so no chemical effect is seen.

Thus, while metals conduct electricity very well, it is mainly conducting liquids (electrolytes) that show useful chemical effects such as electroplating and electrolysis. This is why understanding the nature of the conductor is important in deciding where chemical effects can be applied.

No, the conclusion is incorrect.

Reasoning:

• Lemon juice contains citric acid and water, which provide ions in the solution.
• The fact that the bulb glows, even if dimly, means that some current is passing through the circuit.
• An insulator would not allow any significant current and the bulb would not glow at all.
• The bulb glows dimly because the current is weak, not because the liquid is an insulator.

Correct conclusion: Lemon juice is a weak conductor of electricity, not an insulator. To detect such weak conduction more accurately, an LED or a compass needle test (magnetic effect) should be used instead of an ordinary bulb.

The observation can be explained using the example of copper plating from copper sulphate solution:

• In the solution, copper sulphate exists as Cu²⁺ and SO₄²⁻ ions.
• At the cathode, Cu²⁺ ions gain electrons and deposit as copper metal:
  Cu²⁺ + 2e⁻ → Cu (metal)
• At the anode (made of copper), copper atoms lose electrons and go into solution as Cu²⁺ ions:
  Cu (metal) → Cu²⁺ + 2e⁻
• Thus, the Cu²⁺ ions removed from the solution at the cathode are almost equally replaced by Cu²⁺ ions leaving the anode.
• Because of this balance, the overall concentration of copper ions in the solution remains nearly constant.

The blue colour of copper sulphate solution depends on the concentration of Cu²⁺ ions. Since this concentration does not change much, the colour of the solution remains almost the same during electroplating, even though metal is being deposited on the cathode.

Heating effect:

• When current passes through a conductor, it produces heat.
• Example: Electric iron or heater. The wire (heating element) becomes hot due to current and can be used to iron clothes or heat water.

Magnetic effect:

• When current flows through a wire, it produces a magnetic field around it.
• Example: Electromagnet. A coil of wire with current passing through it behaves like a magnet and can attract iron objects.

Chemical effect:

• When current passes through certain conducting liquids, it causes chemical changes in them.
• Example: Electroplating. Passing current through copper sulphate solution deposits copper on the cathode and dissolves copper from the anode.

All three effects may occur together in some situations, but in Chapter 14 the main focus is on the chemical effect and its applications in electroplating and electrolysis.

The object to be electroplated must receive metal ions from the solution. At the cathode (negative electrode):

• Positive metal ions (like Cu²⁺) are attracted.
• They gain electrons and are converted into neutral metal atoms, which deposit as a thin uniform layer on the object.

Therefore, the object is always connected to the negative terminal of the battery so that it becomes the cathode and receives the metal coating.

If, by mistake, the object is connected to the positive terminal:

• It becomes the anode instead of the cathode.
• Metal atoms from the object may start dissolving into the solution as ions.
• Instead of gaining metal, the object may lose its own metal and become thinner.
• Proper electroplating will not occur on that object; rather, it will gradually corrode in the solution.

Hence, to achieve electroplating, the object must always be connected as the cathode (negative electrode).

Broadly, we can agree that liquids containing ions can behave as electrolytes, but there is a difference in their strength.

Strong electrolytes:

• Solutions where a large number of ions are present, e.g., concentrated acid or strong salt solutions.
• They conduct electricity well and show clear chemical effects like strong gas evolution or rapid metal deposition.

Weak electrolytes:

• Solutions where only a small number of ions are present, e.g., weak acids or very dilute salt solutions.
• They allow only weak current to flow. A bulb may not glow, but an LED may show some conduction.

Non-electrolytes:

• Liquids with covalent molecules but practically no ions, e.g., sugar solution in small concentration, kerosene, pure alcohol.
• These do not behave as electrolytes and do not conduct electricity.

So, while liquids with ions generally act as electrolytes, their conducting ability can be very different, and some liquids may not produce noticeable chemical effects due to very few ions.

When acidified water (water with a small amount of acid) is electrolysed:

• At the cathode (negative electrode), hydrogen gas is produced.
• At the anode (positive electrode), oxygen gas is produced.

Explanation:

• Water molecules partly split into H⁺ and OH⁻ ions, and the acid helps to increase ion concentration.
• At the cathode, H⁺ ions gain electrons and form hydrogen gas (H₂). 2H⁺ + 2e⁻ → H₂ (gas)
• At the anode, OH⁻ ions or water molecules lose electrons and form oxygen gas (O₂) and water. 4OH⁻ → O₂ + 2H₂O + 4e⁻
• The gases escape as bubbles at the respective electrodes. Typically, the volume of hydrogen gas collected is about double the volume of oxygen gas.

This activity shows that electric current can chemically decompose water into its components, hydrogen and oxygen.

Cleaning the surface of the metal object before electroplating is essential because:

• The surface may be covered with dust, grease, rust or oxide layers.
• These layers prevent direct contact between the object’s metal and the metal ions in the electrolyte.
• If the surface is not clean, the deposited metal does not stick properly and forms a weak, patchy layer.

If this step is ignored:

• The plating may be uneven, with some areas getting more deposition and others very little.
• The deposited layer may peel off quickly or get scratched off easily, failing to protect or beautify the object.
• The final product will be of poor quality and may not pass industrial or exam standards.

Therefore, thorough cleaning ensures a smooth, shiny and durable electroplated surface, which is essential in both industry and exams.

Hot electric iron – mainly physical change:

• When current passes through the heating element of an electric iron, it becomes hot due to the heating effect of current.
• The iron plate heats up and can iron clothes, but the material of the heating element does not change chemically.
• When the current is switched off, the iron cools down and returns to its original state.
• This is mainly a physical change, since no new substance is formed.

Electroplating of a key – chemical change:

• When current is passed through copper sulphate solution with a key as cathode and copper as anode, a thin layer of copper is deposited on the key.
• This involves the movement of Cu²⁺ ions, their gaining electrons and forming copper metal on the key.
• A new layer of metal is formed and stuck to the surface; this cannot be reversed easily by simple physical means.
• This is a chemical change because new substance (a new copper layer) is produced with different properties at the surface.

So, a hot iron mainly shows a physical change (heating and cooling), while electroplating is a clear example of a chemical change caused by electric current.

Human body as a conductor:

• The human body contains a large amount of water with dissolved salts and minerals.
• These dissolved substances provide ions, which allow current to pass through the body.

Earth as a conductor:

• The Earth can accept or supply a large amount of charge without much change in its potential.
• Metallic conductors buried in the ground provide a path for electric current to flow into the Earth, making it an effective conductor.

Because both the body and the Earth are conductors, current can flow from a live wire through a person’s body and then into the ground, causing electric shock.

Safety rule based on this fact: Never touch an electrical appliance, switch or wire with wet hands or when standing on a wet floor. Wet skin and water on the floor increase conductivity, making it easier for current to pass through the body to the Earth, which can be very dangerous.

Knowledge of chemical effects of electric current can help in environmental protection in the following ways:

1. Pollution control and waste treatment: Some industries use electrolysis-based methods to treat wastewater. Harmful ions or chemicals can be removed from industrial effluents before they are released into rivers or lakes. For example, heavy metal ions can be deposited on electrodes instead of polluting water bodies.
2. Corrosion prevention and resource saving: Electroplating can prevent corrosion of metal structures like bridges, pipelines and machinery. This increases their life, reduces the need for frequent replacement and saves natural resources used to make new metals. It also reduces the environmental damage caused by mining and metal production.

Thus, by using electrochemical methods wisely, we can reduce pollution, save resources and protect the environment.

In Chapter 14, you learn that:

• Materials are divided into conductors and insulators based on their ability to allow electric current.
• Some liquids, especially solutions of acids, bases and salts, conduct electricity because they contain ions.
• Conductivity of liquids can be tested using circuits with a bulb, LED or compass needle (magnetic effect).
• When current passes through certain solutions, chemical changes occur. These are called the chemical effects of electric current.
• Chemical effects include gas formation, colour change and metal deposition at electrodes.
• Important terms are electrolyte, electrode, anode and cathode.
• In the copper sulphate experiment, copper is transferred from the anode to the cathode, proving chemical effects of current.
• Electroplating is a major application where a thin layer of one metal is deposited on another to protect it from corrosion and improve appearance.
• Electroplating uses the rules: object to be plated is cathode, plating metal is anode, and the electrolyte is a salt solution of that metal.
• Safety precautions must be followed while using electricity and chemicals in experiments.

These points form the core of the chapter and are important for CBSE Class 8 examinations.

One simple and effective project is a “Mini Electroplating Demonstration”.

Materials needed:

• Small battery (6 V or 9 V)
• Connecting wires and switch
• Copper sulphate solution in a beaker
• Copper strip (anode)
• Clean iron nail or key (cathode)
• Stand, labels and chart paper for explanation

Working:

1. Clean the iron nail or key thoroughly.
2. Connect the iron nail to the negative terminal of the battery so that it becomes the cathode.
3. Connect the copper strip to the positive terminal, making it the anode.
4. Dip both electrodes in the copper sulphate solution without letting them touch.
5. Switch on the circuit and allow current to pass for a few minutes.
6. Remove the nail and show the audience the thin reddish-brown copper layer deposited on it.

Explanation for visitors: Explain that electric current causes copper from the solution to deposit on the nail and copper from the strip to go into the solution. This is called electroplating, an example of the chemical effect of electric current, and is widely used in industries to protect metals and make them look attractive.