What is Electric potential
The amount of work needed to move a unit charge from one point to another point against the electric field is called as Electric potential.
Define Electric charge?
- Electric charge is physical property of matter that caused it to experience a force when placed in a electromagnetic field.
- Electric charges can be positive or negative charge
- When an object has more protons (Positively charged) than electrons (negatively charged) object is said to be positively charged.
- When an object has less protons and more electrons, object is said to be negatively charged.
- Like charges repel each other and unlike charges attract each other.
- SI unit of Electric charge is Coulomb
Define Potential difference?
- Potential difference is the amount of work, that is energy required to move an electric charge from one point to another.
- Unit of Potential difference is Volt
What is Voltmeter?
Voltmeter is an instrument used to measure the electric potential difference between two points in an electric circuit. Voltmeter are connected in parallel.
Define Electricity?
- Electricity is the flow of electric charge. It provides energy or power that is used to run electrical and electronic appliances
- Electricity is generated through thermal power stations, windmills, batteries etc.
What is an Electric cell?
- An electric cell is a device that produces electricity from the chemicals stored inside it.
- When the chemicals inside the electric cells are drained out/ used up, it stops to produce the electricity.
- An electric cell has two terminals. Positive and Negative
- Positive side of an electric cell has a metal cap, negative side has a flat metal disc
What is a Battery?
A Battery is combination of two or more cells combined in series to produce higher electricity.
What are the two major types of Electric cells?
The two major types of electric cells are Primary and Secondary cells
Difference between the Primary and Secondary cells?
| Primary Cell | Secondary cell |
| Primary cell are batteries that cannot be reused or recharged | Secondary cell are batteries that can be reused and recharged |
| Cells can be used only once | Cells can be used more than once |
| They have lower self discharge rates and used for long term storage of power | They have higher discharge rate and hence need to be recharged intermittently |
| They are used in portables devices such as battery light, battery fans etc. | They need to be charged before use and are used in automobiles. |
Ammeter is the device used to measure the electric current.
What is a dry cell?
- Electric cell that is normally used in torch and other appliance is known as dry cell.
- It produces energy from the chemicals stored within it.
- A cell connected in a circuit, causes electric current to flow from positive to negative terminal through circuit.
- Dry cell can supply electric charge for specific time
- When the chemicals are exhausted, they cannot be reused any more.
What is an Electric bulb?
- Electric bulb is a device that produce light when electricity is passed through its terminals.
- Thin wire fixed in the middle of glass bulb is called as Filament. Filament glows when the power is ON
- Filament is made of Tungsten.
- Two thick wires provide support to the filament.
- Two thicker wires provide support to the metal case of bulb and other is connected.
- When electricity is passed through terminals of bulb, the filament is heated up and it produces the light.
What makes the bulb to glow?
- There is a flow of electric current between the two wires.
- An electric current has electrical energy.
- When the current flows through the electric bulb, electric energy gets converted into heat and light energy
- Electric current flows from positive terminal through the wires to the negative terminal
What is an Electric circuit?
- When the two ends of cells are connected to bulb using copper wire, bulb lights up
- This is because we have provided a path for the flow of electric current from a positive to negative terminal. This path of electric current is called as Circuit.
What are the elements of the Circuit?
The components/ elements of the circuit are Bulb, Wires, cells and Switches
What is Switch?
An electric switch is a electrical device that serve the purpose of breaking the flow of electrical charges in an electric circuit.
What is complete/ Closed Circuit?
When the circuit allows the flow of electric charges through them, it is said to be a complete/ closed circuit
A switch is said to be ON, when it allows the current to pass through all the components of circuit.
What is broken/ open circuit?
When the circuit path is obstructed, it does not allow the flow of electric charges through them. This is known as broken / open circuit
A Switch is said to be OFF, when it breaks that circuit. That is, when any one of the components are not connected, it does not allow the flow of electric current.
Difference between the Conductors and Insulators?
| Conductors | Insulators |
| The substances through which electricity flow are called as conductors | The substances through which electricity cannot flow are called as Insulators |
| Conductors have large number of free electrons | Insulators do not contain free electrons |
| Electrical resistance of conductors is very low | Electrical resistance of insulators is very high |
| Metals are conductors. Ex: Silver, copper, Aluminium | Nonmetals are insulators. Ex: wood, rubber, plastic |
What are the various types of cells?
- Car battery, usually have six cells within it.
- It can supply more current than dry cell.
- Once exhausted they are recharged with electrical charger and used again and again.
- Smaller cells are used in mobile phones, they can be charged and used again and again
- Some button cells can be recharged, some can be used only once.
- Solar cell is cell that directly converts the solar energy into the electrical energy.
- Solar cells together form the solar panel.
- Many solar cells are used to give electrical power to human made satellites in outer space.
- Solar cells in solar panel give power to streetlights and water pumps in remote places, where there is no electricity.
Formula to calculate the Current, Charge and Time:
Each of them are represented as Current – I, Charge – q, Time – t
To measure current: I = q/t
To measure charge: q = I * t
To measure time: t = q/ I
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