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Updated on 03rd July, 2023 , 7 min read
Electric current is a fundamental concept in physics and plays a crucial role in electrical circuits. It represents the flow of electric charge through a conductor. To understand and calculate current, it is essential to grasp the underlying formula and its application. In this article, we will explore the formula for current, discuss its components, and provide step-by-step guidance on calculating electric current.
An electric current refers to the movement of particles, specifically electrons, through wires and components. It represents the rate at which electric charge flows. When an electric charge flows through a conductor, it indicates the presence of an electric current in that conductor. In circuits utilizing metallic wires, the flow of electrons constitutes the movement of charges.
Ohm's Law states that the voltage (V) across a conductor is equal to the product of the current (I) flowing through it and the resistance (R) of the conductor. According to this law, the current can be determined by dividing the potential difference (voltage) by the resistance. Therefore, the formula for electric current is expressed as: I = V/R, where:
This equation for electric current allows for the calculation of current in a circuit when the voltage and resistance values are known. Furthermore, it can also be employed to calculate either the current or resistance when the other two values are given.
The SI unit for electric charge is the coulomb, and electric current is measured in units of coulombs per second, which is known as the "ampere" (A). The direction of current flow is conventionally considered to be from the negative terminal to the positive terminal of the cell.
Electric current can be classified into two types based on both magnitude and direction.
Where,
I = Strength of current
i = current
R = R0(1 + αΔT)
Where,
Rt is the resistance at temperature t°C
R0 is the resistance at temperature 0°C
α is the temperature coefficient of resistance
Conductivity = Reciprocal of resistivity or σ = 1/ρ = 1/RA
Case 1:When battery is delivering current
V = E – ir
Where,
V is the terminal P.D.
E is the emf of the cell
R is the internal resistance of the cell
R is the external resistance.
Case 2:When battery is charging
V = E + ir
Where,
P, Q, R and S are the resistances in the bridge.
Where,
x is the unknown resistance of given wire
R is the resistance in the resistance box
L1 is the balancing length from the left end of the bridge to Jockey.
ρ=Lπr2X
Where,
ρ is the resistivity of the wire
x is the resistance of wire
A is the Area of cross section of the wire,
L is the length of the wire.
Emf of the cell in the secondary circuit
Es = Iρ
(i) Comparison of emf's of two cells
E1/E2 = L1/L2
Where,
E1- emf of first cell
E2 – emf of the second cell
l1 and l2-the balancing lengths of individual cells, respectively.
(ii) For determination of the internal resistance of the cell:
r = R (L1 - L2)/L2
To calculate electric current using the formula, follow these steps:
Step 1:Determine the charge (Q) in coulombs.
Step 2: Measure the time (t) in seconds.
Step 3:Substitute the values into the formula I = Q / t.
Step 4:Calculate the result, which will be the electric current in amperes (A).
Let's illustrate the application of the formula for current through an example:
Solution:Using the formula I = Q / t: I = 12 C / 4 s I = 3 A
Hence, the electric current is 3 amperes.
This formula is fundamental in various electrical calculations, such as circuit analysis, power calculations, and understanding the behavior of electrical components.
Solution:Resistance (R) = 70 Ω
Voltage (V) = 220
The electric current formula as per the Ohm's Law is given as
I = V / R
I = 220 / 70
I = 3.1428 Amperes
Solution:Given that
I = 50 A
R = 14Ω
Using the Electric Current Formula as per Ohm's Law
I = V/R
50 = V/14
V = 50 × 14
V = 700 Volts
Thus, the potential difference is 700 V.
Current, as a fundamental concept in electricity, finds numerous applications in various fields. Some notable applications of electric current include:
These are just a few examples highlighting the broad range of applications of electric current in our daily lives and across various industries. The versatility and controllability of current make it a crucial aspect of modern technology and infrastructure.
When an electric field is present, a small quantity of electric charge placed within it will be subjected to force. As a result, work needs to be done on the positive charge. In certain substances like electrolytes and ionized gases, both positively charged ions and negatively charged ions are in motion, forming what is known as an electric current. If a total of n electrons traverses the cross-section of a conductor within a specific time period t, the overall charge passing through the conductor can be expressed as Q = n × e.
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By - Nikita Parmar 2023-08-25 09:48:44 , 11 min readThe formula for electric current is I = V/R, where I represents the current in amperes (A), V represents the voltage in volts (V), and R represents the resistance in ohms (Ω).
The formula I = V/R represents Ohm’s Law, which states that the current flowing through a conductor is directly proportional to the voltage across it and inversely proportional to the resistance of the conductor.
To calculate the current, divide the voltage (V) by the resistance (R). For example, if the voltage is 12 volts and the resistance is 4 ohms, the current would be 12/4 = 3 amperes.
The unit of measurement for current is the ampere (A), which is equivalent to the flow of one coulomb of charge per second.
Yes, the formula can be rearranged to calculate voltage or resistance if the other two values are known. For example, to calculate voltage, rearrange the formula as V = I * R.
Yes, the formula for current (I = V/R) is applicable to both DC (direct current) and AC (alternating current) circuits, as long as the voltage and resistance values are appropriate for the type of current being considered.
If the voltage increases while the resistance remains constant, the current will also increase. This is because the current is directly proportional to the voltage according to Ohm’s Law.
According to Ohm’s Law, as the resistance increases, the current decreases, given a constant voltage. Conversely, as the resistance decreases, the current increases.
Yes, the formula can be used for complex circuits with multiple components by applying it to individual components or sections of the circuit. The total current in such circuits is determined by the combination of currents in each component.
While the formula for current provides a basic understanding of its calculation, it’s important to note that factors like temperature, material properties, and circuit configurations can also influence current flow in real-world scenarios. These factors may require additional considerations beyond the basic formula.
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