CHEMICAL EFFECTS OF ELECTRIC CURRENT | Class 8 Science Notes
By ConceptScroll Team · Published on 17 July 2026 · 3 min read
CHEMICAL EFFECTS OF ELECTRIC CURRENT – this guide gives you a concise, exam-ready overview of CHEMICAL EFFECTS OF ELECTRIC CURRENT from Class 8 Science, written by ConceptScroll editors and reviewed against the latest NCERT textbook.
Chemical Effects of Electric Current
When an electric current passes through a conducting liquid, chemical changes occur in the liquid and on the electrodes. This is because the conducting liquid contains ions, which move towards the electrodes of opposite charge. Positive ions (cations) move towards the cathode (negative electrode), and negative ions (anions) move towards the anode (positive electrode). At the electrodes, these ions either gain or lose electrons, resulting in chemical reactions such as deposition of metals or liberation of gases. This process is called electrolysis. The chemical effect of electric current is observed in electrolytes, which are substances that conduct electricity in molten or aqueous states due to the presence of ions. For example, when electric current is passed through molten lead bromide, lead metal is deposited at the cathode and bromine gas is released at the anode. This shows that electric current can cause chemical decomposition of compounds into their elements.
📊 Diagram: Diagram shows a simple setup for electrolysis with two electrodes dipped in molten lead bromide connected to a battery. Lead deposits at cathode and bromine gas bubbles at anode.
🧪 Activity: Activity: Passing electric current through molten lead bromide and observing deposition of lead and liberation of bromine gas.
🔗 Connection: This section leads to a detailed study of electroplating and other applications of chemical effects of electric current.
Frequently asked questions
1. Fill in the blanks. (a) Most liquids that conduct electricity are solutions of __________, __________ and __________. (b) The passage of an electric current through a solution causes __________ effects. (c) If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the __________ terminal of the battery. (d) The process of depositing a layer of any desired metal on another material by means of electricity is called __________.
(a) Most liquids that conduct electricity are solutions of acids, bases and salts.
(b) The passage of an electric current through a solution causes chemical effects.
(c) If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the negative terminal of the battery.
(d) The process of depositing a layer of any desired metal on another material by means of electricity is called electroplating.
2. When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. Can you explain the reason?
The magnetic needle shows deflection because the solution conducts electricity, allowing current to flow through the circuit. The current produces a magnetic field around the wire, which causes the magnetic needle to deflect.
3. Name three liquids, which when tested in the manner shown in Fig.11.9, may cause the magnetic needle to deflect.
Three liquids that may cause the magnetic needle to deflect are: 1. Salt water (solution of common salt in water) 2. Lemon juice (acidic solution) 3. Vinegar (acetic acid solution)
4. The bulb does not glow in the setup shown in Fig.11.10. List the possible reasons. Explain your answer.
Possible reasons why the bulb does not glow: 1. The liquid in the container may not be conducting electricity (e.g., pure water). 2. There may be a loose connection or break in the circuit. 3. The bulb may be fused or faulty. 4. The battery may be dead or not connected properly.
Explanation: For the bulb to glow, the circuit must be complete and the liquid must conduct electricity to allow current flow. If any of these conditions fail, the bulb will not glow.
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