What is a resistor?

Summary

This script defines a resistor as a passive electrical component that limits electric current. It uses the water flow analogy to explain its function, comparing water pressure to voltage and the narrowing of a tube to a resistor's effect on current. Ohm's law, discovered by Georg Simon Ohm in 1827, is introduced to describe the relationship between current, voltage, and resistance. The script also covers various types of resistors, including fixed, variable, and those with resistance dependent on physical quantities, and touches on their applications and construction materials. It concludes with a brief explanation of how to read resistor color bands to determine their value and tolerance.

Takeaways

• 🔌 A resistor is a passive electrical component that limits the flow of electric current.
• ⚡ The standard symbols for resistors are a zigzag line, with the American standard on the left and the IEC standard on the right.
• 💧 The script uses the analogy of water flow through a tube to explain how resistors work in an electrical circuit.
• 📉 Resistors cause a voltage drop across them, similar to a pressure drop in a water pipe when it narrows.
• ⚖️ Ohm's law, discovered by Georg Simon Ohm in 1827, states that resistance is equal to voltage divided by current (R = V/I).
• 🔋 A simple circuit with a battery and a resistor can demonstrate Ohm's law, where the resistor limits the current to a desired level.
• 💡 An example application is a basic LED circuit, where a resistor is used to prevent the LED from burning out by limiting the current.
• 🔩 There are various types of resistors, including fixed, variable, and those with resistance that varies with physical quantities like light or temperature.
• 📏 Fixed resistors are the most common and come in through-hole and surface-mount device (SMD) packages.
• 🔄 Variable resistors can adjust resistance mechanically and are known as potentiometers or rheostats depending on their application.
• 🌐 Resistors can be categorized by material and construction, such as wirewound, carbon composition, carbon film, metal film, and metal oxide film.

Q & A

What is the primary function of a resistor?

A resistor's primary function is to limit the flow of electric current in an electrical circuit.

What are the standard symbols for resistors according to the American and International standards?

The standard symbol for resistors in the American Standard is a zigzag line, while the International Electrotechnical Commission (IEC) uses a similar zigzag symbol but with a different shape.

How does a resistor create a voltage drop in a circuit?

A resistor creates a voltage drop by having a higher resistance than the connecting leads, which causes a reduction in electrical current, similar to how a narrow part in a water pipe creates a pressure drop.

Who discovered Ohm's law and what does it state?

Ohm's law was discovered by the German scientist Georg Simon Ohm in 1827. It states that electrical resistance is equal to voltage divided by current.

How can Ohm's law be used to calculate the resistance needed for a circuit with a specific current and voltage?

Ohm's law can be used to calculate the resistance needed by using the formula Resistance = Voltage / Current. For example, if you want a current of 4 amps with a voltage source of 2 volts, the resistance needed would be 0.5 ohms.

What is the purpose of using a resistor in an LED circuit?

In an LED circuit, a resistor is used to limit the current to a safe level to prevent the LED from burning out due to excessive current.

How can you calculate the resistance needed to limit the current to a specific value using Ohm's law?

To calculate the resistance needed to limit the current to a specific value, use Ohm's law: Resistance = Voltage / Current. For instance, to limit the current to 30 milliamps with a 9-volt battery, the resistance would be 300 ohms.

What are the different types of resistors mentioned in the script?

The script mentions fixed resistors, variable resistors, and resistors with varying resistance dependent on physical quantities. Fixed resistors include carbon composition, carbon film, metal film, and metal oxide film types. Variable resistors include potentiometers and rheostats.

What is the difference between a potentiometer and a rheostat?

A potentiometer is a variable resistor used as a voltage control device, while a rheostat is a variable resistor used to control the current in a circuit.

What is the significance of the color bands on a resistor, and how can you read them?

The color bands on a resistor indicate its resistance value and tolerance. The first and second bands represent the first two digits of the resistance value, the third band is the multiplication factor, and the fourth band indicates the tolerance. For example, a resistor with red, blue, gray, and gold bands has a value of 2.6 megaohms with a 5% tolerance.

Where can one find more information about resistor types, properties, and color codes?

More information about resistor types, properties, and color codes can be found at websites like resistorguide.com, which also offers a color code chart and an automatic calculator to decode resistor values.

Outlines

00:00

🔌 Understanding Resistors and Their Applications

A resistor is defined as a passive electrical component that primarily limits the flow of electric current. It can be visualized using the analogy of water flowing through a tube, where the resistor acts like a constriction, reducing the flow. The standard symbols for resistors are depicted in both American and International standards. Ohm's law, discovered by Mr. Ohm in 1827, describes the relationship between voltage, current, and resistance. A simple circuit example with a battery and a resistor demonstrates Ohm's law, where the resistor's value is calculated to achieve a desired current. Resistors are used in various applications, such as LED circuits, where they prevent excessive current that could damage the LED. Different types of resistors include fixed, variable, and those with resistance varying based on physical quantities. Fixed resistors are the most common, while variable resistors can be adjusted mechanically or electronically. The video also touches on the various materials and constructions of resistors, such as wirewound, carbon composition, carbon film, metal film, and metal oxide film resistors, each with its unique characteristics and applications.

05:01

🎨 Resistor Color Coding and Marking Systems

This paragraph delves into the marking systems used to indicate the resistance value and tolerance of resistors. The example given is a carbon composition resistor with four color bands. The first band represents the first digit of the resistance value, the second band the second digit, the third band indicates the multiplication factor, and the fourth band signifies the tolerance. The video provides a practical guide on how to read these color codes, suggesting the use of a resistor color code chart or an automatic calculator for decoding. The specific example given is a resistor with bands of red, blue, gray, and gold, which corresponds to a resistance value of 2.6 megaohms with a 5% tolerance. The video encourages viewers to visit resistorguide.com for more information on color codes, resistor types, and properties.

Keywords

💡Resistor

A resistor is a passive electrical component that limits the flow of electric current in a circuit. In the video, it is likened to a narrow part in a water pipe that restricts water flow, analogously reducing the current in an electrical circuit. The concept is central to understanding how resistors function within a circuit to control current flow.

💡Ohm's Law

Ohm's Law is a fundamental principle in electrical engineering that describes the relationship between voltage, current, and resistance in a circuit. It is defined as resistance being equal to voltage divided by current (V=IR). The video uses Ohm's Law to calculate the required resistance for a circuit to achieve a desired current, illustrating its practical application in circuit design.

💡Voltage

Voltage, measured in volts, is the electrical potential difference that causes current to flow in a circuit. The video script mentions a voltage source as the driving force behind the current and uses the example of a 9-volt battery to explain how voltage influences the need for a resistor to limit current.

💡Current

Electric current, measured in amperes (amps), is the flow of electric charge in a circuit. The video script uses the analogy of water flow to explain current and how resistors can be used to limit this flow, preventing potential damage to components like LEDs.

💡IEC Standard

The International Electrotechnical Commission (IEC) standard is an international norm for symbols used in electrical diagrams. The video mentions the IEC standard symbol for a resistor, indicating a commitment to global understanding and consistency in electrical engineering.

💡American Standard

The American Standard symbol for a resistor is one of the ways to represent resistors in electrical diagrams. The video contrasts this with the IEC standard, highlighting the importance of recognizing different conventions in the field of electronics.

💡Fixed Resistor

A fixed resistor is a type of resistor with a constant, unchanging resistance value. The video script describes fixed resistors as the most common, used in various applications, and available in different packages like axial and SMD, emphasizing their versatility and widespread use.

💡Variable Resistor

Variable resistors have an adjustable resistance value, allowing for dynamic control of current in a circuit. The video explains two types of variable resistors: potentiometers, used for voltage control, and rheostats, used for current control, showcasing their utility in adjustable circuit designs.

💡Carbon Film Resistor

Carbon film resistors are made with a thin carbon film on a non-conductive core. The video script notes their higher accuracy compared to carbon composition resistors, making them widely used in electronics. This type is highlighted to show advancements in resistor technology.

💡Resistor Color Code

The resistor color code is a system of colored bands on resistors that indicate their resistance value and tolerance. The video provides an example of decoding a carbon composition resistor's color bands to determine its value and tolerance, illustrating a practical skill for identifying resistor specifications.

💡LED Circuit

An LED circuit is a specific application of resistors where they are used to limit current to prevent damage to light-emitting diodes (LEDs). The video script uses the example of a red LED with a 9-volt battery to demonstrate how a resistor can be calculated and used to protect the LED, showing a real-world application of resistors.

Highlights

A resistor is a passive electrical component that limits the flow of electric current.

Standard symbols for resistors include the zigzag (American Standard) and the rectangle with a wave (IEC Standard).

Resistors function similarly to narrowing a water pipe to reduce flow, creating a pressure drop.

Ohm's Law, discovered in 1827, relates resistance, voltage, and current in a circuit.

Resistors create a voltage drop when current flows through them, similar to a pressure drop in a pipe.

An example circuit with a battery and resistor illustrates Ohm's Law, calculating resistance needed for a desired current.

Resistors are used to prevent damage to LEDs by limiting current to a safe level.

Resistors have various applications and purposes in electrical circuits.

Fixed resistors have a constant resistance value and are the most common type.

Variable resistors can adjust resistance, used as potentiometers or rheostats.

Resistors can also vary resistance based on physical quantities like light or temperature, used for measurement.

Resistors are categorized by material and construction, including wirewound, carbon composition, carbon film, metal film, and metal oxide film types.

Wirewound resistors offer durability and accuracy but can have parasitic reactants at higher frequencies.

Carbon composition resistors are old and can withstand high energy pulses despite inferior properties.

Carbon film resistors are widely used for their higher accuracy compared to carbon composition types.

Metal film resistors offer better accuracy and lower temperature coefficients than carbon film types.

Metal oxide film resistors are durable and have high temperature resistance and reliability.

Foil resistors provide the highest precision and stability, with a metallic foil as the resistive element.

Resistors are marked with colored bands indicating resistance value and tolerance, following a specific color code.

Resistor color codes can be deciphered using charts or automatic calculators for quick identification.

Transcripts

what is a resistor a good definition

might be this one a resistor is a

passive electrical component with a

primary function to limit the flow of

electric current the standard symbols

for resistors are given below zigzag on

the left is the American Standard and

the one on the right is the

international standard by the

IEC to explain the definition more

clearly we use the example of water that

flows through a tube the flow of water

is similar to the electrical current in

an electrical circuit

the pressure difference that causes the

water to flow can be compared to a

voltage difference which causes the flow

of electrical

current if we create a resistance in the

flow of water the current will reduce we

can do this for example by making the

tube more narrow at a certain place a

resistor does pretty much the same the

resistor has a higher resistance than

the connecting leads and causes a

reduced electrical current we can see

this in the water pipe that a pressure

drop is created because of the narrow

part in the middle the pressure on the

left is bigger than on the right the

resistor has a similar effect here a

voltage drop is created the relation

between the electrical current voltage

and resistance is described by Ohm's law

Mr oh was a German scientist that

discovered in

1827 that electrical resistance is equal

to voltage divided over current in this

formula resistance is in ohms voltage in

volts and current in

amps a simple circuit with a battery and

a resistor can EXP explain this the

voltage source causes a current which is

limited by the

resistor the voltage source is 2 volts

and we want a current of 4

amps so what resistance should the

resistor have according to Ohm's law the

resistance is equal to the voltage

divided over current or 2 over 4 is

equal to 0.5 ohms an example of an

application of this simple network is a

basic LED

circuit suppose we want to light a red

liid with a 9volt battery

the LI has a specified maximum current

of 30

milliamps if we directly connect a

battery the LI might burn out instantly

the liid practically doesn't create

resistance so the current will get much

higher than the 30 milliamps to prevent

this we can place a resistor at the

positive lead between the battery and

the

liid the resistor should have a

resistance which is just high enough to

reduce the flow of current to 30

milliamps using ohms law again we we

know that resistance is equal to voltage

divided over current or 9 volts divided

over 0.03 amp is 300 ohms if we now

connect also the negative lead and

create a circuit the LD emits a nice red

light using a resistor for An Li circuit

is just one application but there are

numerous other applications and purposes

for resistors to give a complete

overview would be absolutely impossible

in this short video there are a lot of

different resistor types all with their

own applications characteristics and

construction fixed resistors have a

constant resistance value and they are

the most common type when people talk

about a resistor they most probably mean

a fixed resistor the picture shows an

actual carbon film resistor fixed

resistors are available in Axel and SMD

packages variable resistors have an

adjustable resistance

value most variable resistors are

adjusted by mechanical movement when

they are used as a variable voltage

device

they are called

potentiometers when they are used as

variable resistance to control the

current in the circuit they are called

rats digital potential meters are

controlled electronically instead of bi

mechanical action a third category are

resistors which have a varying

resistance dependent on a physical

quantity such as light temperature or

voltage they are often used as

measurement devices another breakdown of

resistor types can be made according to

resistance material and

construction ywi resistors are the

oldest type which are still used today

they are constructed by winding a

resistive wire around a non-conducting

core they can have very low resistance

values and can be produced fairly

accurate furthermore they are very

durable a disadvantage is the parasitic

reactants for higher

frequencies carbon composition resistors

are constructed with a mixture of a

non-conducting keramic and fine carbon

particles they are also very old and

used to be the most common resistor type

of few decades ago although their

properties are inferior to other types

regarding for example tolerance they are

still in demand for certain applications

for example they have the ability to

withstand high energy pulses carbon film

resistors are widely used today they are

made out of a non-conducting core with a

thin carbon film around it carbon film

resistors have a higher accuracy than

carbon composition resistors but have

inferior properties compared to metal or

metal oxide film metal film resistors

have similar construction as carbon film

resistors but have a metal layer instead

of a carbon film they have a better

accuracy a lower temperature coefficient

and a fairly good stability metal oxide

film resistors are even more durable and

have a higher temperature resistance and

reliability than the metal film

resistors foil resistors have a

resistive element of a thin metallic

foil of several micrometers thick they

have the highest available precision and

stability today most actual leaded

resistors have a marking with colored

bands to indicate resistance value and

tolerance this resistor is a carbon

composition resistor with four color

bands the first band gives the first

digit of the resistance value the second

band gives the second digit the third

band indicates a multiplication factor

and the fourth band gives away the

tolerance of the

resistor you can try to memorize the

meaning of each band and color but you

can also use the resistor color code

chart to decipher the code at

resistorguide.com you can even find an

automatic calculator to deser code for

you using the chart we see that the

first red band has a value of two the

second blue band is six the third band

is gray which means a multiplication

factor of

10,000 the golden four band means a

tolerance of 5% we know that the

resistor has a value of 2.6 megaohms

with a tolerance of

5% you can find a lot more information

about the color code H resistor types or

resistor properties at resistor guide

Doom