Content Strategy Manager
Electric current refers to the rate of flow of electrons in a given conductor. It is measured with Ampere as its SI unit. Charged particles like electrons or ions flow through a current-carrying conductor. Electric current makes it possible for electricity to move from one place to another. Electric current is measured using a device known as an Ammeter. It measures the amount of charge moving through the cross-section at a given point in time.
Key Takeaways: Capacitance, Electric Charge, Electric Potential, Electromotive force, Electricity, Ampere, Current electricity, Electrons, Electric current, Ions
What is Electric Current?
[Click Here for Previous Year Questions]
Electric Current is the flow of charged particles through a conducting medium, like a wire. At the point when we talk about electricity, the charged particles we're referring to quite often are electrons. The quantity of electrons that moves determines the ability of a material to conduct electricity.
Electric Current
- The molecules in a conducting material have lots of free electrons that glide around from one place to another.
- The movement of these electrons is random.
- When we apply a voltage to the conductor, all the free electrons will move in a similar way, producing electric current.
- Something interesting about electric flow is that while the electrical energy moves through the conveyor at almost the speed of light, the actual electrons move a whole lot more slowly.
- Electrons are small particles that exist within a substance's molecular structure of a substance. They are either tightly or loosely held.
- Depending on the way they are held, electrons can freely travel within certain limits.
- The movement of these electrons is referred to as electric current.
Electric Current
Depending on the ability of the material to conduct electricity, they are classified into two categories: conductors and insulators.
Conductors
Materials that allow the electric current to pass through them easily are known as conductors. The charge carriers inside metallic conductors are free electrons. When an electric field is applied, the free electrons experience a force and an electric current is set up inside the conductor. The force that is required to drive the current flow through the conductor is known as voltage.
Examples of conductors: Silver, Gold, aqueous solutions of salts and metals like iron and Human body, etc.
| Note: Charge carriers in various conductors-
|
Conductors
Discover about the Chapter video:
Current Electricity Detailed Video Explanation:
Insulators
Materials that restrict the free flow of electrons from one particle to another are known as insulators. The particles of the insulator do not allow the flow of electrons; subsequently, the charge is randomly distributed evenly across the surface of an insulator.
Examples of Insulators: Glass, Wood, Plastic, etc.
Insulators
Visualizing Electric Current
[Click Here for Sample Questions]
To get a better understanding of what an electric current is and how it acts in a conductor, we can utilize the water pipe analogy of electricity. Unquestionably, there are a few constraints however they fill in as an extremely essential representation of the current and current stream.
We can compare the electric current with the water moving through the pipe. At the point when pressure is applied to one end of the pipe, the water is compelled to move through the pipe in one way. The measure of water flow is relative to the pressure set on the end. This pressure can measure up to electromotive force.
Electric Current Water Analogy
Unit of Electric Current
Unit of electric current = Unit of Charge/Unit of time.
- The SI unit of Charge is Coulomb and that of time is second.
- Then, the Unit of electric current = Coulomb/second, known as Ampere.
Thus, the SI unit of Electric current is Ampere which is known as Coulombs per second.
1 unit of Electric current is defined as the amount of charge that flows through the cross-section area (the area of cross-section doesn't matter as we are talking about the amount of charge) of a conductor in unit time.
Properties of Electric Current
[Click Here for Previous Year Questions]
Electric current is a significant quantity in electronic circuits. We have adapted electricity in our daily lives so much that it becomes impossible to imagine life without it. Therefore, it is important to understand what is current and the different properties of the electric current.
- Electric current is the result of the flow of electrons.
- The work done to move an electron stream is known as electrical energy which can be converted into various different forms such as light energy and heat energy.
- The SI unit used to measure electric current is ampere. One ampere of current represents one coulomb of electric charge that moves past a specific point in one second.
1 ampere = 1 coulomb / 1 second
- At the point when an electrical potential distinction is applied across the metallic wire, the approximately appended free electrons begin moving towards the positive terminal of the cell.
- This consistent progression of electrons comprises the electrical flow. The progression of flows in the wire is from the negative terminal of the cell to the positive terminal through the outside circuit.
- As per the electron hypothesis, when the potential contrast is applied across the transmitter some matter moves through the circuit which establishes the electric flow.
- It was viewed that this matter streams from higher potential to lower potential, for example, the positive terminal to the negative terminal of the cell through the outside circuit.
Do Check Out:
Ohm’s Law
Ohm's law is one of the most important laws in the field of electrical current. It helps in determining the relationship between electrical current and potential difference. This law was named after a German Physicist, George Simon Ohm. The law is applicable for current flowing through conductors and states that,
Ohm's Law
The electric current flowing through a conductor is directly proportional to the amount of voltage applied to it.
Conventional Flow Vs Electron Flow
- Positive charge flow is the conventional direction of current flow.
- Electrons being negatively charged are attracted to the positive charges.
- Electrons thus always flow from the negative to the positive terminal.
Types of Current
[Click Here for Sample Questions]
There are two types of electrical current:
Direct Current (DC)
In Direct Current, the direction of current will not be changed and will move in a single direction, mostly all types of batteries use direct current only. Examples- computers, telephones, and satellites.
Alternating Current (AC)
The movement of electric charge reverses direction in a periodic pattern in its system. Alternating Current is a category of electric power that is delivered to businesses and residences. Audio and radio signals carried on electrical wires are some examples of AC
AC and DC Current
Prerequisites for the current to flow in a conductor
[Click Here for Previous Year Questions]
To create an electric current, three things are required: a supply of electric charge (electrons) that are allowed to flow, some type of push to move the charges through the circuit, and a pathway to convey the charges. The pathway to convey the charges is typically a copper wire.
Electron flow in a conductor
The circuit includes a source of energy (a battery) that produces voltage. Without voltage, electrons randomly move and are undirected; therefore electric current cannot flow. Voltage creates pressure on the electrons allowing them to flow in a single direction. The circuit forms a closed conducting loop through which the electrons can flow. A circuit is said to be closed when the switch is turned ON.
What is an Electromotive Force?
[Click Here for Sample Questions]
Electromotive Force (emf) is an estimation of the energy that makes current flow through a circuit. It can likewise be characterized as the possible contrast in control between two points in a circuit. Electromotive force isn't genuinely a force; rather, it is an estimation of energy for each unit charge. Its SI unit is volts.
Electromotive Force
Also Check Out:
Effects of Electric Current
[Click Here for Previous Year Questions]
When an amount of current flows through a conductor, there are a number of phenomena that tell if a current is flowing or not. Following are the most prominent phenomena:
Heating Effect of Electric Current
When our clothes are folded, we use the iron box to make our clothes fresh and neat. Iron box work on the principle of heating effect of electric current. There are numerous devices that work on the heating effect. When an electric current flows through a conductor, heat is generated in it. For example, converting steam energy to electricity wastes energy in a modest quantity.
The heating effect is given in the following equation:-
H = I2RT
The heating effect depends on the given factors:
- The amount of electric current measured in Amperes. The larger the amount of current is, the higher the heat is produced.
- The electrical resistance of the conductor, R, is measured in Ohms. The higher the resistance, the higher the heat produced.
- The time ‘t‘ for which the current flows, is measured in seconds. The longer the current flows in a conductor, the more heat is generated.
Magnetic Effect of Electric Current
Electric Current produces a magnetic force which can likewise be named the magnetic effect. The magnetic impact of electric current is known as electromagnetic impact.
- When a compass is brought close to a conveyor, the needle gets redirected in direction of the flow of electricity. This shows that Electric Current creates a magnetic effect.
- Magnetic fields are made by the magnetic impact of an electric current and magnetic material.
Magnetic Effect of Electric Current
Chemical Effect of Electric Current
When an electric current is passed through a solution, it breaks down further into ions. The Chemical Effect of electric current is ordinarily clarified by electrolysis. In electrolysis, the chemical separation of ionic compounds can be accomplished by the entry of direct electric current through them. On the basis of the nature of the solution, the following effects can be noticed:
- A change in the color of the solution
- Metallic deposits on the electrodes
- Production of bubbles or release of gas in the solution.
Drift Velocity
[Click Here for Sample Questions]
Electrons have a tendency of moving around all the time, but when they come into an electric field, they move toward a particular direction (where the electric field is applied). The average velocity at which these electron drifts is called drift velocity, or can be called the average velocity of an electron.
The formula used to calculate drift velocity is
I = nAvQ
- where I is electrical current
- n is the number of electrons
- A is the area of the conductor
- v is the drift velocity
- Q is the charge of an electron
- The standard unit of drift velocity is m/s.
Measurement of Electrical Current
[Click Here for Previous Year Questions]
Current can be measured using an ammeter. It is also measured by detecting the magnetic field associated with the current.
Techniques to Measure Current
- Shunt resistors
- Hall effect current sensor transducers
- Transformers
- Magnetoresistive field sensors
- Rogowski coils
- Current clamps
Resistive Heating and Electrical Current
Resistive Heating is also known as resistance, ohmic, or joule heating. It is a simple process in which heat is produced when an electric current passes through a conductor. This happens due to friction. The process is now very commonly used in home appliances like toasters and electric heaters.
Things to Remember
- Steady electric currents and electric flow have reformed the method of living.
- Electric Current is the flow of charged particles through a conducting medium, like a wire.
- Materials that allow the electric current to pass through them easily are known as conductors. The charge carriers inside metallic conductors are free electrons.
- Materials that restrict the free flow of electrons from one particle to another are insulators.
- Electromotive force (emf) is an estimation of the energy that makes current flow through a circuit.
- As per the electron hypothesis, when the potential contrast is applied across the transmitter some matter moves through the circuit which establishes the electric flow.
- Electric Current produces a magnetic force which can likewise be named the magnetic effect.
Do Check Out:
Previous Year Questions
- If now we have to change the null point at the 9th wire, what should we do?… [DUET 2007]
- The electrical permittivity and magnetic permeability of free space are… [DUET 2003]
- Just after key K is pressed to complete the circuit, the reading will be …. [KEAM 1999]
- The resistance between any two terminals is when connected in a triangle is…. [NEET 1993]
- potential drop through 4Ω4Ω resistor is… [NEET 1993]
- The potential difference per unit length of the wire will be… [NEET 1999]
- Value of R for which the power delivered in it is maximum is given by... [NEET 1992]
- In a closed circuit, the current II (in ampere) at an instant of time tt (in second) is given by…? [KEAM]
- Five cells each of emf E and internal resistance r send the same amount of current through…? [KEAM]
- Electrical conductivity is the reciprocal of…? [KEAM]
- Consider a cylindrical conductor of Length L and area of cross-section A. The specific conductivity…? [KEAM]
- An ammeter, voltmeter, and a resistor are connected in series to a cell and the readings are…? [KEAM]
- A potentiometer wire of length 10m and resistance 20Ω is connected in series with a…? [KEAM]
- A potentiometer wire, 10m long, has a resistance of 40Ω. It is connected in series with a…? [KEAM]
- A given resistor has the following color code of the various strips on it: Brown, black, green…? [KEAM]
- A galvanometer can be converted into an ammeter by connecting…? [KEAM]
- A copper wire with a cross-section area of 2×10−6m2 has a free electron density equal… [KEAM]
- 4 cells each of emf2 V and internal resistance of 1O are connected in parallel to a load resistor…? [KEAM]
- A circuit is made using R1, R2, R3, R4, and a battery as shown in the following figure. Find the equivalent…? [KEAM]
- A battery of 6V and internal resistance of 2Ω is connected to a silver voltameter. If the current of…? [KEAM]
Sample Questions
Ques. What is electric current and its formula? (2 marks)
Ans. An electric current is the flow of charge per unit of time. This current is identified with the voltage and resistance of a circuit. It is very well represented by I and the SI unit is Amperes. Electric flow relates to the electric charge and the time.
According to Ohm's law, the electric flow equation will be
I=V/R
Ques. What is the electric current direction? (2 marks)
Ans. The direction of electric current is the direction in which the positive charge would move. In wires, the genuine charge transporters negatively charged electrons. In any case, the show utilized for the heading of current depends on the direction in which positive charges would move.
Ques. What is the current formula? (2 marks)
Ans. The relationship between current and resistance in an electric circuit. Current is usually represented by the symbol I. Ohm's law relates to the current flowing through a conductor to the voltage V and resistance R; that is, V = IR. An alternative to Ohm's law is I = V/R.
Ques. Define 1 unit of Electric Current. (2 marks)
Ans. 1 unit of Electric current is defined as the amount of charge that flows through the cross-section area (the area of cross-section doesn't matter as we are talking about the amount of charge) of a conductor in unit time.
Ques. How does the mobility of electrons in a conductor change, if the potential difference applied across the conductor is doubled, keeping the length and temperature of the conductor constant? (2019)
Ans. The mobility can be determined by: 
= vd / E
Vd can be referred to as the drift velocity and E as the electric field.
Drift velocity: vd = (-Ee/m)r
When we substitute this particular value in the mobility equation
= (-e/m)r
If the length and temperature of the conductor remain unchanged there would not be any change in the time of relaxation r. The mobility of the possible difference would also be independent. Hence there would not be any difference in the mobility of electrons if the possible difference is altered keeping the temperature and length constant.
Ques. Nichrome and copper wires of the same length and same radius are connected in series. Current I is passed through them. Which wire gets heated up more? Justify your answer. (2017)
Ans. Nichrome wire will heat up more. As we know:
R = ρ(I/A)
RCu/RNi = ρCu/ρNi
ρCu < ρNi
RCu < RNi
H = I2Rt
H 
R
Ques. A resistance of R draws current from a potentiometer. The potentiometer wire, AB, has a total resistance of R0. A voltage V is supplied to the potentiometer. Derive an expression for the voltage across R when the sliding contact is in the middle of the potentiometer wire. (2017)
Ans.
The similar resistance in between A and C is,
½ = ½ + 1/(R0/2)
R = R (R0/2) /R + (R0/2) = RR0 / 2R + R0 …(i)
Similar resistance in between A and B,
Req = (RR0/2R+R0) + (R0/2)
Req = R0(4R + R0) / 2(2R + R0) …(ii)
Current present in the circuit,
I = V/Req = V..2(2R + R0) / R0(4R + R0)
The voltage throughout R:
VR = I.R’
VR = [V.2(2R + R0) / R0(4R + R0)] * RR0/(2R +R0)
VR = 2VR / 4R+R0
Ques. Two cells of EMFs 1.5 V and 2.0 V having internal resistances of 0.2 Ω, and 0.3 Ω, respectively are connected in parallel. Calculate the emf and internal resistance of the equivalent cell. (2016)
Ans. Provided:
E1 = 1.5V, r1 = 0.2Ω
E2 = 2V, r2 = 0.3Ω
![Equivalent emf E = [(E1/r1) (E2/r2)] / (1/r1) (1/r2)](https://images.collegedunia.com/public/image/I13_88a8f5c7a5871072642f03db1d4670ca.jpeg)
Equivalent emf E = [(E1/r1)+(E2/r2)] / (1/r1)+(1/r2)
= [(1.5 * 0.3) + (2 * 0.2)] / (0.2 + 0.3)
= (0.45 + 0.4) / 0.5
= 0.85/0.5
= 1.7volt
Equivalent internal resistance:
= r1r2 / r1+r2
= (0.2*0.3) / (0.2+0.3)
=0.06/0.5
req = 0.12Ω
Ques. (a)Define the term drift velocity.
(b) On the basis of electron drift, derive an expression for resistivity of a conductor in terms of the number density of free electrons and relaxation time. On what factors does the resistivity of a conductor depend?
(c) Why alloys constantan and manganin are used for making standard resistors? (2016)
Ans. (a) The avg velocity with the help of which the independent electrons are attracted towards the positive terminal under the influence of the applied electric field is called the drift velocity.
u1→ + u2→ + ……. uN→ / N = 0
I.e., Vd = eE
/m
(b) We are aware that the current which is flowing through the conductor is:
I = nAevd
I = neA[-(eE
/m)]
When we apply E = -(V/l)
I = neA(eV/ml)
= (ne2At/ml)V = (1/R)V
IαV→by Ohm’s Law
When we take R = ml/nAe2 
as fixed for a certain conductor at a certain temp and is called the resistance of the conductor.
R = (m/ne2
)1/A = ρl/A
ρ = (m/ne²
)
ρ is the particular resistivity of the material present in a wire. It is dependent on the number of independent electrons per unit volume and temperature.
(c) Alloys like constantan and manganin are used for making standard resistors for the following reasons:
- They contain a great value of resistance.
- They are very little affected by temperature
- The temp coefficient of resistivity in alloys like constantan and manganin is low.
For Latest Updates on Upcoming Board Exams, Click Here: https://t.me/class_10_12_board_updates
Check-Out:
Comments