Definition of electrical resistance and Ohm’s law…and exercises on them with their solutionsnada shaban
Definition of electrical resistors
Resistance is an electrical component that limits the flow of electric current within a circuit. The example most often used to explain this idea is to compare the electric current to the flow of water inside a hose. A resistor can be likened to a contraction inside the hose to limit the flow of water.
The majority of those interested in physics know Ohm’s Law of Resistance: V = IR / V , and V means the voltage through the resistance, and I is the current flowing inside the resistor, while R is the resistance. This is the equation that links current, voltage, and resistance, and it is the rule for working with resistors and negative components. The other.
Under the microscope, resistors are made up of a variety of materials that conduct electricity, but they are not a perfect solution, so the ability of electrons to flow is limited by the atomic structure of the materials that are chosen, by different properties of the conductor such as the conductive material, as well as the surface area and duration of use, possibly. Resistance Control Due to precision, resistance is measured by Ohm’s law, and the symbol for resistance is Ω.
Definition of Ohm’s law
Ohm’s law can be used to ensure the correct and constant values of the electrical circuit, the rates of electrical current, methods of supplying voltage, and reducing the voltage. If, for example, the test tool knows to measure a current that is higher than normal, this may indicate that the resistance has decreased or that the voltage has increased, which It determines a high voltage condition. This may indicate a problem with the display or circuit.
In a direct current circuit, measuring a current that is weaker than normal may indicate that the voltage has decreased, or the resistance of the circuit has increased. Possible reasons for an increase in resistance are weak, loose, corrupted, or damaged connectors.
Loads are placed in a circuit on electrical current. Loads can be through any type of component, such as: small electrical appliances, computers, or household appliances. Most of these loads are contained within a nameplate with an attached sticker. These nameplates provide a safety certificate and many reference numbers. .
Technicians say about the nameplates written on the devices to indicate the standard values of voltage and current. During the test, if the technicians realize that the customary values are not shown on the various digital measuring devices or their clamp meters, then Ohm’s law can be used to find out which part of the circuit is facing a problem, and from here the determination is made. The place where the problem may exist.
Factors on which electrical resistance depends
Resistance is considered the resistance to the flow of electric current through a conductor. The resistance of an electrical circuit can be measured digitally. Conductor and resistance are inversely proportional. The higher the conductivity, the lower the resistance.
Resistance = potential difference / current.
The factors on which the conductor depends, it depends on the following factors:
- Conductor temperature.
- Point of conductor’s cross section.
- Conductor components and materials.
Electrical resistance is directly proportional to the length (L) of the conductor and inversely proportional to the cross-sectional area (A).
The equation is: “R = ρl / A”, and ρ is the resistance of the material and is measured in micrometers, and ohms in metres.
Resistance is a measure of the quality of a material’s ability to resist the release of electric current. It appears that insulators will have a higher resistance value than conductors.
Ohm’s law exercises and applications
- First exercise:
Find the current I through the resistor for resistance R = 2 Ω if the voltage across the resistor is 6 volts.
Replace R with 2 and V with 6 in Ohm’s law V=IR / V.
6 = 2 I
Solve to get I
I = 6 / 2 = 3 A
- Second exercise:
In the circuit attached below, the resistors R1 and R2 are located in series and have resistances of 5 Ω and 10 Ω. Therefore, the voltage through resistor R1 = 4 volts. Find the current passing through resistor R2 and the voltage through the same resistor.
The electrical circuit to be solved in the second exercise.
We use Ohm’s law V=IR / V to find the current I1 that passes through R1.
4 = 5 I1
Solve for I1
I1 = 4 / 5 = 0.8 A
The two resistors are in series and consequently the same current flows through them, so the current I2 to R2 is 0.8 A.
We now use Ohm’s law to find the voltage V2 across resistor R2.
V2 = R2 I2 = 10 (0.8) = 8 V
- Third exercise:
In the picture below, resistors R1 and R2 become the same and have resistances of 8 Ω and 4 Ω, in series, current passing through R1 = 0.2 A Find the voltage through resistor R2 and the current passing through the same resistor.
The electrical circuit to be solved in Example 3.
Use Ohm’s law V=IR / V to find out the voltage V1 across resistor R1.
V1 = 8(0.2) = 1.6 V
The voltage across resistor R1 and the voltage across resistor R2 are the same because R1 and R2 are parallel.
Ohm’s law is used to find the current I2 that flows through resistor R2.
1.6 = 4 I2
Solve for I2
I2 = 1.6 / 4 = 0.4 A
How important is Ohm’s law?
- Electrical circuits are available everywhere in daily life, from the complex integrated circuits that control the device to the wires that give the ability to turn on or off a light bulb, for example, at home. Our entire life would be very different if we were not surrounded by electrical circuits that are available everywhere we go.
- Ohm’s law is one of the equations that is related to understanding electrical circuits, but to understand it correctly, it will require a sound understanding of the main rules that connect voltage, current, and resistance. Ohm’s law is simply the equation that explains the relationship between the three inside conductors.
- Electric potential is considered the most widely used term to know the difference in electrical potential between two points. It explains the impulse that gives the electric charge the opportunity to move through a continuous loop. The German physicist Georg Ohm describes the relationship between voltage, current and resistance in the form of an equation called by his name, the formula of Ohm’s law V = IR / V.
- Ohm’s law is considered very important for clarifying electrical circuits because it connects voltage to current, where the value of the resistance modifies the connection between the two. For this reason, Ohm’s law can be used to control the amount of current inside the electrical circuit, and add resistors to limit the flow now and keep it from increasing the amount of current. It is also used to describe electrical power, which is the rate of flow of power per second, because power is P = IV, and can therefore be used to ensure that the circuit is providing sufficient power, for example for a 60 watt device.
- The most notable thing about Ohm’s law is that it gives a person the ability to analyze circuit diagrams, especially when combined with Kirchhoff’s laws, which follow them. Ohm’s law can be used to find the unknown quantity of the three, provided that you determine the other two quantities for the given electrical circuit. The work is explained to you through some examples. Home on how to do this.
- Kirchhoff’s voltage law states that the voltage drop at any closed loop in a circuit is always zero. The current law states that the amount of current emanating to a junction or node in the circuit is equivalent to the amount emanating from it. Ohm’s law can be used with the voltage law specifically to calculate the voltage drop. During any component of the circuit, which is a known problem in electronics categories.
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