chemical effects of electric current- Class 8

  What is electricity or electric current?

The flow of electric charge is known as Electric Current, Electric current is carried by moving electrons through a conductor.
By convention, electric current flows in the opposite direction to the movement of electrons.

Electric current is actually the movement of electrons.

Electric current is denoted by the letter ‘I’

S.I. unit of electric current is ampere (A).

                                      

2:- What is the formula of electric current?

Ans:- Electric current is expressed by the rate of flow of electric charges. Rate of flow means, the amount of charge flowing through a particular area in unit time.

If a net electric charge (Q) flows through a cross-section of a conductor in time t, then,

Where 

I = electric current, 

Q = net charge

t = time

3:- Write some metals that are conductor of electricity.

Ans:- gold, silver, brass, iron

4:- What is electric circuit?

Ans:- Electric circuit is a continuous and closed path of electric current.

5:-  What is LED?

Ans:- LED stands for Light Emitting Diode. It glows even when a weak current flows through it. LED has two leads attached to it. one lead is longer than other. The longer lead is always connected to the positive terminal of the battery and the shorter lead to the negative terminal of the battery.

                                            

6:- How can we use magnetic compass as a tester?

Ans:- Magnetic compass is a better tester because the deflection of the magnetic needle can be seen even if the current is small. We can use a magnetic compass as a tester by keeping it near the wire of circuit. When the current flows through the circuit then the magnetic needle of  magnetic compass shows deflection.

7:- Why does the tap water conductor of electricity?

Ans:- Tap water is conductor of electricity because tap water is not pure. It contains dissolved impurities like salt and natural minerals which make it conductor of electricity

8:- Why does the distilled water Non-conductor of electricity?

Ans:- distilled water is Non-conductor of electricity because distilled water is pure and free from salts and natural minerals.

9:- How can we make distilled water conductor?

Ans:- We can make distilled water conductor by adding salt and natural minerals. Presence of salt in a liquid make it a good conductor of electricity. Liquid that conduct electricity are solutions of acids, bases or salts.

10:- Write short notes on William Nicholson's invention.

Ans:- In 1800, William Nicholson, a British chemist, showed that bubbles of oxygen and hydrogen were produced if electrodes were immersed in water. He also showed that oxygen bubbles were formed at anode and hydrogen bubbles we3re formed at cathode. 

11:-  What are electrolytes?

Ans:- Substances that do not conduct electricity when solid, but do when molten or dissolved in water are called electrolytes.

Ex:- acids, metal oxides, metal hydroxides, and salt

12:- What is Electrolysis?

Ans:- Electrolysis is a method of separating bonded elements and compounds by passing an electric current through them. It uses a direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. 

13:- What is electrolytic cell?

Ans:- An cell that uses electrical energy to drive a non-spontaneous redox reaction. In this cell electrical energy is converted to chemical energy is called electrolytic cell.

14:- Write a short notes on mechanism of electrolysis.