Answer:

Question 1.

What are good conductors?

Answer:

The substances that conduct electricity through them are called good conductors.

Question 2.

What are insulators or poor conductors?

Answer:

The substances that do not conduct electricity through them are poor conductors or insulators.

Question 3.

Give four examples of conductors.

Answer:

Copper, iron, aluminium and brass.

Question 4.

Give four examples of insulators.

Answer:

Air, wood, rubber and plastic.

Question 5.

Name two metal objects which have a coating of another metal.

Answer:

Handlebars of bicycles, bathroom taps.

Question 6.

What do we get on electrolysis of acidified WATER?

Answer:

Hydrogen and oxygen gas.

Question 7.

Is air a bad or good conductor?

Answer:

A bad conductor.

Question 8.

Which metal is plated on handle bars of cycles and rim of wheels?

Answer:

Chromium

Question 9.

What is the full form of LED?

Answer:

LIGHT Emitting Diode.

Question 10.

How do we check the electric current?

Answer:

We check the electric current by using a tester.

Question 11.

Which part of an atom is responsible for flow of current?

Answer:

Electron

Question 12.

Why do most liquids conduct electricity?

Answer:

Due to the presence of ions in them, most liquids conduct electricity.

Question 13.

An LED is more efficient device than a bulb. Why?

Answer:

LED is more efficient because it can glow even when a weak or less current flows through it.

Question 14.

Do lemon JUICE or vinegar conduct electricity?

Answer:

Yes, they conduct electricity.

Question 15.

How is conductivity of liquids tested?

Answer:

By using a tester.

Question 16.

Is water from taps, handpumps, wells and ponds a good conductor?

Answer:

Yes, water from these sources is a good conductor.

Question 17.

What makes distilled water a good conductor?

Answer:

Salts when mixed with distilled water make it a good conductor.

Question 18.

Why is a layer of zinc coated over iron?

Answer:

To prevent iron from corrosion and rust.

Question 19.

Will the SOLUTION of sugar in distilled water conduct electricity?

Answer:

No

Question 20.

Why is tin electroplated on iron to make cans used for storing food?

Answer:

Tin is less reactive than iron. Tin coating prevents food from coming in contact with iron and thus pre¬vents it from getting spoiled or corroded.

Question 21.

Why we ifse chromium electroplating on taps and bars of bicycle instead of silver and gold?

Answer:

Silver and gold are very expensive comparatively to chromium.

Question 22.

What type of effect of current do the deposits of metal on electrodes show?

Answer:

Chemical effect

Question 23.

What effect of current does electroplating show?

Answer:

Chemical effect

Question 24.

Which effect of current causes the bulb to glow?

Answer:

Heating effect

Question 25.

Which part of the bulb glows?

Answer:

Filament

Question 26.

Name the three effects of electric current.

Answer:

Heating, magnetic and chemical effect.

Question 27.

How can the magnetic effect of current be checked?

Answer:

By using magnetic compass.

Question 28.

What do we see when the compass needle is brought NEAR a wire in which current is flowing?

Answer:

The needle deflects.

Question 29.

What is electroplating?

Answer:

Deposition of thin layer of a metal over other metal by electrolysis is called electroplating.

Explanation: