8th Science NCERT Chapter 11
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Topics to study from the chapter "Chemical Effects of Electric Current" along with 1-2 lined summaries for each topic:
1. Conduction of Electricity in Liquids:
– Liquids can conduct electricity, and this can be tested using a tester by completing a circuit.
2. Conductivity Testing Activity:
– Demonstrating the conductivity of liquids like lemon juice or vinegar using a tester with a bulb that glows when electricity passes through.
3. Effect of Electric Current on Magnetic Field:
– Understanding how an electric current produces a magnetic effect, seen in the deflection of a compass needle, and using this effect to create another kind of tester.
4. Classification of Materials as Conductors:
– Differentiating between good and poor conductors of electricity based on testing various liquids like tap water, vegetable oil, milk, and honey.
5. Testing Distilled Water Conductivity:
– Testing distilled water to show that it is a poor conductor of electricity and observing how the addition of salt to distilled water makes it a conductor due to the presence of salts.
These topics cover essential concepts regarding the conduction of electricity through liquids and the effects of electric current on different materials.
What materials conduct electricity, according to the chapter?
Metals like copper and aluminium conduct electricity, while materials like rubber, plastic, and wood do not conduct electricity.
How can you test whether a liquid conducts electricity?
To test whether a liquid conducts electricity, you can use a tester with a battery, dip the ends of the tester into the liquid, and observe if the bulb glows, indicating the flow of electric current.
Describe the activity to test the conduction of electricity through lemon juice or vinegar.
In the activity, a tester is used with the ends dipped in lemon juice or vinegar. If the liquid allows electric current to pass, the circuit is complete and the bulb glows, indicating that lemon juice or vinegar conducts electricity.
Why may the bulb not glow even when a liquid conducts electricity?
The bulb may not glow even when a liquid conducts electricity if the current in the circuit is too weak. This can happen when a material conducts electricity but not as easily as a metal, leading to a weak current flow.
How can you make a different kind of tester to detect a weak current?
Another kind of tester can be made using the magnetic effect of currents. By wrapping a wire around a tray, placing a compass needle inside it, and connecting the wire to a battery terminal, a tester is created to detect a weak current by observing the deflection of the compass needle.
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