Wednesday , September 23 2020

NCERT 8th Class (CBSE) Science: Chemical Effects of Electric Current

Question: What is electric current?

Answer: The flow of electrons constitutes an electric current.

Question: How is electronic current different from conventional current?

Answer: The flow of electronic current is from negative to positive whereas the flow of conventional current is from positive to negative.

Question: Differentiate between conductors and insulators.

Answer: Difference is as follows:

1. Substances which allow electric charges to flow through them are called conductors of electricity.
1. Substances that do not allow electric charges to flow through them are called non-conductors or insulators of electricity.
2. Examples: Metals like iron, copper, aluminium, etc. 
2. Examples: Plastic, rubber, wood, etc.

Question: What is an electrolyte?

Answer: A substance which conducts electricity in the liquid state or when dissolved in water and breaks up chemically during the process is called an electrolyte.

Question: Why is zinc electroplated on iron?

Answer: Zinc is electroplated on iron to prevent it from rusting.

Question: Draw a circuit diagram showing a dry cell connected to a bulb through a switch. Mark the positive and the negative terminals of the cell, and the direction of flow of a. electron, b. conventional current.


Circuit diagram showing a dry cell connected to a bulb
Circuit diagram showing a dry cell connected to a bulb


Question: What are the advantages of electroplating iron with chromium?

Answer: Chromium is a shiny metal that does not corrode and resists scratches. It makes iron look more attractive and also resist corrosion.

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One comment

  1. Can be more informative!

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