# Electricity

Question 1 Define the term electric current?

Question 2 What is the SI unit of electric current?

Question 3 Define the term ampere?

Question 4 What is an open electric circuit?

Question 5 What is a closed electric circuit?

Electricity

The flow of water in rivers and canals is called water current.

The flow of charge in a conductor(metallic wire)is called electric current.

An electric current is defined as amount of charge flowing through any cross-section of a conductor in unit time.

Charge(Q)

Electric current(I)=——————-

Time(t)

Q

I=—-

t

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

Electric current through a conductor is said to be 1 ampere if 1 coulomb charge flows through any cross-section of conductor in one second.

Milliampere=10-3  A

Microampere=10-6 A

In conductors the electric current is due to flow of negatively charged electrons.

The direction of electric current in a conductor or wire is just opposite to direction of flow of electrons in the conductor.

Electric current is a scalar quantity.

Ammeter is used to measure electric current.

Resistance of an ideal ammeter is zero.

An ammeter is always connected in series in an electric circuit.

Positive ammeter should be connected to positive cell or battery.

Negative ammeter should be connected to negative cell or battery.

A continous and closed path of electric current is called electric current.

For Ex:An electric bulb connected to cell with the help of connecting wires.

An electric circuit through which no electric current flows is called an open electric circuit.

For Ex:If the plug of the key is taken out or wires are broken.

An electric circuit through which current can flow continously is called as closed electric circuit.