Electric Current

There existed a time when no electronic devices were available, devices like laptops, and cellphones, there even was a time when humans did not have a fan to cover the heat or light in the house to see in the dark, but in today’s time, People have all these in their hands’ reach, all this was possible because of one invention – “Electricity”. Electricity is the flow of electric charges when a potential difference is available at the ends of the wire. It will not be incorrect to say that Humans mostly rely on Electricity not only for easy living, but it become a way of life. From Rockets to Trains to Factories to our home appliances, everything works on electricity.

What is Electric Current?

The flow of electric charges is known as electric current. In earlier times, it was considered that correct flow was due to the movement of positive charges from the positive terminal to the negative terminal. But after the discovery of electrons, the conventional wisdom was proven wrong as the positive charge is nothing but the deficiency of the electron. Now, scientists know that correct itself is generated due to the movement of negative charges (electrons), electron flow from the negative terminal of the system to the positive terminal, which is known as Electron flow, and unlike electrons, current flows in the opposite direction i.e., from the positive terminal to negative terminal, which is also known as Conventional Current flow.

The best way to imagine current flowing in a circuit is by imagining the flow of liquid inside a pipe from a higher point to a lower one, the liquid represents current, and the difference in the heights of the extreme end of the pipe represents the difference in potential causing the current to flow if the pipe is twisted at some point the flow of the liquid will slow down, that represents the resistance offered by the conductor that reduces the current.

Electric Current Formula

The electric current can be represented as the rate of flow of electric charge (q) which mathematically can be represented as follows: 

Unit of Electric Current

As Electric Charge and Time come under the Fundamental quantities and their units are respectively Coulomb and second. So by the definition of Electric Current, its unit is Coulomb/second.

The SI Unit of electric Current is Ampere (A).

In CGS system, unit of electric current is biot or sometimes called an abaampere.

What is EMF?

Normally, in a conductor, Electrons are present, and they are not stationary, they keep on moving in random directions, and due to their randomness, the overall displacement of all electrons becomes zero and hence, no current is produced. In order to produce current, some external force is required to align electrons in one direction and make them move in that one direction, this external force is known as Electromotive Force and is also famous as EMF. It is nothing but the voltage applied to produce current.

Types of Electric Current 

There are two types of electric current, which are as follows:

Alternating Current

Electric current with its direction and values keep changing is known as Alternating Current. The values of AC in one direction increase from 0 to peak value then falls down to 0 again, then in opposite direction increase from 0 to peak value then come back to 0. 

As electric current goes from 0 to peak in one direction and the same in opposite direction, it behaves like a wave more specifically a sine wave and it has some frequency. For example, in India, the grid provides 60 Heartz 220 Volts AC but in America, their grid provides 120 Volts 50 hearts AC.

Direct Current

Electric current with the same direction always is known as Direct Current. As the direction of DC remains the same, so its frequency is 0. 

Properties of Electric Current

• Current is due to the Flow of electrons in the circuit.
• Electric current can be categorized as AC and DC in nature, where DC is the direct current that flows in only one direction, DC is used in low-voltage applications, aircraft applications, etc. AC is known as alternating current, and it flows in both directions alternatively, AC is the current that comes in our houses and the appliances work on AC.
• The electric current in a circuit can be controlled by introducing resistance to the circuit.
• The unit of Electric current is Amperes (A). 1 Ampere can be defined as the flow of 1 coulomb of charge in 1 second.
• Electric current flows from Higher potential to Lower Potential in a circuit (from positive terminal to negative terminal) also known as the conventional current flow direction.

Ohm’s Law

The German physicist Georg Simon Ohm stated that the current flowing in a wire is directly proportional to the voltage drop across it. According to Ohm’s Law, the current flowing through a wire is directly proportional to the voltage applied at the ends of the wire provided that the temperature and conductivity remain the same.

V∝I

Upon removing the proportionality sign, a proportionality constant is introduced known as Resistance.

Where, 

V is Voltage at the ends of conductor

R is Resistance offered by the conductor

I is Current through the wire.

Ohm’s law can be illustrated using the following illustration,

Effect of Electric Current

There are different effects that can be noticed due to the flow of electric current in a wire, for example, when current passes through a resistor, the resistor has a property of resisting which does not let the whole current pass but since energy can neither be created nor destroyed, it is converted in heat energy and is released in the form of heat, this effect is called as the heating effect of current. Similarly, we have the magnetic and chemical effects of electric current.

Chemical effect of Electric Current

When Electric current is passed through a which is conducting in nature, the solution breaks in its respective ions, and effects are seen visibly. The major effects that are prominent,

• The color of the solution may change.
• The deposition of metal at the electrodes may be seen.
• There can be the formation of gas bubbles at the electrodes.

Magnetic effect of Electric current

Electric current is nothing but the motion of electrons, and it is known, when charges are stationary, they create Electric Field but when charges are in motion, they create a Magnetic field. When current is passed through a wire and a metallic sheet is placed there with a needle, the needle will be deflected due to the presence of a magnetic field which is produced by the electric current. One of the biggest applications of the Magnetic effect of electric current is Electromagnets, they are formed with the help of passing current.

Heating effect of Electric Current

When current flows in a conductor, heat energy is produced and released from the conductor and the amount of effect depends upon the resistance offered by the conductor. If the conductor has to offer high resistance, it simply means that it shall not allow most of the current to flow but due to the conservation of energy (energy can neither be created nor destroyed), current that could not pass is converted into heat and the phenomenon is known as the Heating effect of current. The formula for heat energy is given by,

Where, H is Heat energy released

I is current flowing in the conductor

R is Resistance offered by the conductor

T is Time for which the current was flowing in the conductor.

Applications of the heating effect of current involve Electric Irons, Electric Heaters, filament lamps, Electric kettles, etc.

Solved Examples of Electric Current

Question 1: In a conductor, 10 Coulombs of charge flow for 5 seconds, determine the current produced.

Solution:

The current in a circuit is given by,

I = q/t

⇒ I = 10/5 Amperes

⇒ I = 2 Amperes

Therefore, 2 amperes of current flows in the circuit.

Question 2: Which material is a better conductor of electricity — Iron or Silicon?

Answer:

Iron is a better conductor of electricity while silicon is a semiconductor.

Question 3. What is the best conductor of electricity? 

Answer: 

Silver is known to be the best conductor of electricity.

Question 4: In the circuit given below, Find the current flowing through the circuit.

Solution:

In the figure provided, it is clear that there are two resistances, and they are in series. When two or more than two resistances are attached in series in a circuit, the overall resistance becomes equal to the sum of individual resistances present in the circuit.

R = R₁+ R₂

⇒ R = 2+ 2

⇒ R = 4 ohms

From Ohms Law, we know

V = IR

⇒ I = V/R

⇒ I= 20/4

⇒ I= 5 Amperes 

Question 5: Why Silver is not used more often as a conductor in daily usage?

Answer:

Silver is known to be the best conductor of electricity but is still not preferred to be used in daily usage as a conductor because of its unavailability and the fact that silver is very expensive. Instead, conductors like copper which are easily available are used.

Question 6: What is the Heat energy produced when 2 amperes of current is flowing in a circuit for 5 seconds having an overall resistance in the circuit of 4 ohms?

Solution:

The Heat energy produced is given by,

H= I²RT

⇒ H= (2)²×4 × 5

⇒ H= 16 × 5

⇒ H= 80 Joules

Therefore, 80 Joules is produced in the circuit.

FAQs on Electric Current

Question 1: What is Electric Charge?

Answer: 

Electric charge is the fundamental property of matter that exists due to the presence or absence of an electron in an atom. It is a physical property that tells us how strangely an object will behave when placed in an electromagnetic field.

Question 2: What is Electric Current?

Answer: 

Rate of flow of electric charge in a closed is known as Electric Current.

Question 3: What is the si unit of electric current?

Answer:

SI unit of electric current is Ampere.

Question 4: Define ampere.

Answer:

In a conductor if 1 Coulomb of charge passes in 1 second of time, then we say 1 Ampere current is flowing through that conductor.

Question 5: An instrument that detects electric current is known as________.

Answer: 

Instrument for measuring electric current is known as Ammeter.