Electricity | Grade 8 Science DepEd MELC Quarter 1 Module 5 Part 1 Voltage, Current, Resistance

Summary

This educational video delves into the fundamentals of electricity, highlighting its indispensable role in modern life. It explains the concept of electron movement as the core of electrical energy, using the analogy of water flow to illustrate voltage, current, and resistance. The video also addresses the safety aspect by contrasting how birds can safely perch on high-voltage wires without electrocution, unlike humans. It sets the stage for further exploration of Ohm's Law and the interplay between current, voltage, and resistance.

Takeaways

• 🔌 Electricity is a fundamental aspect of modern life, powering devices and machines we use daily.
• 🐦 Birds can sit on high voltage power lines without getting electrocuted because they don't complete an electrical circuit.
• ⚡ Electricity involves the movement of electrons, which is essential for devices like TVs and smartphones to function.
• 🔁 A closed loop is necessary for electricity to flow, creating a path for electrons to move from a power source, through a device, and back to the ground.
• 🚫 When a bird touches two wires with different electrical potentials, it creates a path for electricity to flow through its body, which can be dangerous.
• 🔋 Voltage, or electric potential difference, is what motivates electrons to move through a circuit, and it's measured in volts.
• 💧 Current, analogous to the flow of water, is the rate at which electric charge moves through a circuit, measured in amperes or amps.
• ➗ Resistance is the opposition to the flow of electric current, influenced by the material's properties and its dimensions.
• 🔗 Ohm's Law relates voltage, current, and resistance, showing that voltage is directly proportional to current and inversely proportional to resistance.
• 🔬 George Ohm's contributions to understanding resistance led to the definition of the ohm as a unit of resistance.

Q & A

Why don't birds get electrocuted when they sit on high voltage power lines?

Birds do not get electrocuted when sitting on a single wire because their feet are at the same electrical potential, providing no motivation for electrons to travel through the bird's body, thus preventing electric current.

What is the fundamental concept of electricity discussed in the video?

The fundamental concept of electricity discussed is the movement of electrons, which is essential for powering devices and machines we use daily.

How is electricity generated and maintained in a circuit?

Electricity is generated and maintained in a circuit through a closed loop where electrons are pulled from the ground by a power station, move through power lines and devices, and return to the ground, creating a continuous flow.

What is the role of electrical potential in the flow of electrons?

Electrical potential, or voltage, provides the motivation for electrons to move. It is the difference in charge between two points that drives the flow of electrons through a conductor.

Why are birds safe from electrocution when perched on a single wire, but not when they touch a second wire or the pole?

Birds are safe on a single wire because it does not create a path for current through their bodies. However, touching a second wire or the pole, which is grounded, creates a path for current and can lead to electrocution.

What is the significance of a closed loop in an electrical circuit?

A closed loop is significant because it allows for the continuous flow of electrons, which is necessary for electricity to function and power devices.

What are the three basic principles of electricity mentioned in the video?

The three basic principles of electricity mentioned are voltage, current, and resistance, which describe the behavior of electrons and the flow of charge in a circuit.

How is voltage defined and what is its unit of measurement?

Voltage is defined as the difference in charge between two points on a circuit and is measured in volts, which is the potential energy difference that imparts one joule of energy per coulomb of charge that passes through it.

What is the relationship between voltage and current in an electrical circuit?

Voltage is the cause and current is the effect. There is a direct proportionality between voltage and current, meaning higher voltage results in higher current.

What is the role of resistance in an electrical circuit and how does it affect the flow of current?

Resistance is the tendency of materials to resist the flow of charge. It affects the flow of current inversely; the lower the resistance, the higher the current that can flow through the circuit.

How does the width of a hose in the water tank analogy relate to resistance in an electrical circuit?

In the water tank analogy, the width of the hose represents resistance. A narrower hose restricts the flow of water (analogous to the flow of charge), just as higher resistance in a circuit restricts the flow of current.

Outlines

00:00

🔌 Understanding Electricity and Bird Safety on Power Lines

This paragraph introduces the concept of electricity as an essential part of modern life, highlighting its role in daily activities and the ubiquity of electronic devices. It raises the intriguing question of why birds can perch on high-voltage power lines without getting electrocuted. The explanation lies in the closed-loop system of electricity, where electrons move from the ground, through power lines and devices, and back to the ground. Birds, with their feet on the same wire, do not create a path for current to flow through their bodies due to the lack of electrical potential difference. However, touching a second wire or a grounded object could create a path for current, posing a risk to the birds. The paragraph also humorously contrasts the bird's safety with the danger humans face when coming into contact with electricity.

05:02

🔋 Exploring Voltage, Current, and Resistance in Electricity

The second paragraph delves into the fundamentals of electricity, focusing on voltage, current, and resistance. Voltage is described as the potential energy difference between two points in a circuit, measured in volts, and is symbolized by 'V'. It is likened to water pressure in a tank, where the water represents charge. Current, symbolized by 'I', is the flow of charge, analogous to the flow of water through a hose, and is measured in amperes or amps. The paragraph introduces the concept of resistance, symbolized by the Greek letter omega (Ω), which is the opposition to the flow of charge, similar to the width of a hose affecting water flow. The unit of resistance, the ohm, is defined in relation to current and voltage, and different materials have varying resistance levels. The length and thickness of a conductor also affect its resistance, with longer and thinner wires having higher resistance. The analogy of water flow is used to explain the relationship between voltage, current, and resistance, emphasizing that voltage can be generated in various ways, not just through friction.

10:04

💧 Analogies and the Role of Resistance in Electric Current

This paragraph continues the exploration of electrical concepts with a focus on resistance. It uses the analogy of water tanks and hoses to explain how resistance affects the flow of current. A narrower hose, representing higher resistance, allows less water (charge) to flow compared to a wider hose. The paragraph discusses how increasing the charge (water in the tank) can compensate for higher resistance, thus maintaining current flow. It introduces the concept of ohms as a unit of resistance, where one ohm is the resistance that allows one ampere of current to flow under one volt of pressure. The discussion also covers how different materials, lengths, and cross-sectional areas of conductors influence resistance. The effects of moisture on resistance are highlighted, explaining why dry hands are safer when handling electrical appliances. The paragraph concludes by emphasizing the importance of understanding resistance in the context of electrical conductivity and current flow.

15:06

🔄 The Dynamics of Current, Voltage, and Resistance in Electrical Circuits

The final paragraph summarizes the relationships between current, voltage, and resistance in electrical circuits. It clarifies the conventional current direction, which is from the positive to the negative terminal of a battery, despite electrons actually flowing from the negative to the positive terminal. The paragraph explains that the continuity of the circuit is crucial for current flow, and breaking the circuit will stop the current and manifest the full voltage across the break. It introduces ammeters for measuring current and voltmeters for measuring voltage, detailing their proper connections in a circuit. The relationship between voltage and current is described as direct, with higher voltage leading to higher current, while the relationship between resistance and current is inverse, with lower resistance allowing higher current. The paragraph concludes by reinforcing the importance of understanding these fundamental electrical concepts, setting the stage for further exploration of Ohm's Law in upcoming videos.

Keywords

💡Electricity

Electricity is the flow of electrons through a conductive medium, which is a central theme of the video. It is vital for powering many devices we use daily, such as smartphones and light bulbs. The video emphasizes how integral electricity is to modern life, noting that its absence would severely disrupt daily routines.

💡Electrons

Electrons are subatomic particles that orbit the nucleus of an atom and are responsible for the flow of electricity. The video explains that the movement of electrons through devices like TVs provides energy for them to function, illustrating this with the example of a closed loop system where electrons move from the power station, through the device, and back to the ground.

💡Voltage

Voltage, measured in volts, is the difference in electrical potential between two points. It is what drives the flow of electrons, as described in the video with the analogy of water pressure in a tank. The video also mentions Alessandro Volta, after whom the unit of voltage is named, and how voltage is essential for creating a closed loop for electricity to flow.

💡Current

Electric current is the flow of electric charge, typically measured in amperes or amps. The video uses the water flow analogy to explain current, stating that it is the rate at which charge is flowing. It is directly proportional to voltage, as higher voltage results in higher current, which is crucial for the operation of electrical devices.

💡Resistance

Resistance is the opposition to the flow of electric current and is measured in ohms. The video likens resistance to the width of a hose, where a narrower hose offers more resistance to water flow. It also discusses how different materials, such as conductors and insulators, affect resistance, and how factors like length and thickness of a wire influence it.

💡Ohm's Law

Ohm's Law, mentioned at the end of the video, is a fundamental principle in electricity that relates voltage, current, and resistance. It states that the current through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance between them. The video sets up for a future discussion on how these three quantities interact.

💡Conductors

Conductors are materials that allow the easy flow of electric charge, such as copper, steel, and aluminum. The video explains that these materials have many loosely held electrons, making them good for conducting electricity. This property is essential for the functioning of electrical circuits and devices.

💡Insulators

Insulators are materials that resist the flow of electric charge, making them useful for preventing the unwanted flow of electricity. The video contrasts insulators with conductors, highlighting their high resistance to electric current. This concept is important for understanding safety in electrical systems.

💡Circuit

A circuit, as discussed in the video, is a closed loop that allows the flow of electric charge from one point to another. It is composed of components that control the flow of charge, enabling the use of electricity to power machines and devices. The video emphasizes that a complete circuit is necessary for electricity to function effectively.

💡Electrical Potential

Electrical potential is the capacity for electric charge to do work, and it is a key concept in understanding how electricity flows. The video uses the analogy of water pressure to explain how electrical potential, or voltage, can motivate electrons to move through a conductor, which is essential for the operation of electrical devices.

Highlights

Electricity is essential to modern life, powering everything from smartphones to light bulbs.

Birds can sit on high-voltage power lines safely because their two feet are at the same electrical potential, preventing current from flowing through their bodies.

Electricity flows in a closed loop, requiring a circuit to move electrons through devices.

Electrons need a difference in electrical potential (voltage) to move through a circuit.

If a bird touches a second wire with a different electrical potential, it creates a path for current to flow through its body, potentially electrocuting it.

Humans are at risk of electrocution because their bodies can provide a path to ground, completing the circuit.

Voltage, current, and resistance are the three fundamental principles that describe electrical flow.

Voltage is the difference in electrical charge between two points, measured in volts.

Current is the rate at which electric charge flows, measured in amperes or amps.

Resistance is the opposition to the flow of electric charge, measured in ohms.

The analogy of water flowing through pipes helps to explain voltage, current, and resistance: voltage is water pressure, current is the flow of water, and resistance is the width of the pipe.

The higher the resistance in a circuit, the lower the current for a given voltage.

George Ohm's law defines the relationship between voltage, current, and resistance: current is directly proportional to voltage and inversely proportional to resistance.

Materials with loosely held electrons, like copper and aluminum, are good conductors of electricity, while insulators have high resistance.

In a battery, the positive terminal has a surplus of charge, while the negative terminal has a deficiency. This difference drives the movement of electrons.

Transcripts

[Music]

in this video

we are going to discuss about

electricity electricity has become a

vital part of our lives

the discovery of electricity has changed

the way we work

play and go about our daily routines

the moment we wake up we use our

smartphones to check for notifications

in social media

in the evening we use light bulbs to see

clearly

in fact we are surrounded with devices

and machines that use electricity

electricity has become so important that

if taken away

life comes to a standstill

have you ever noticed birds sitting on

electrical wires on the streets

how can these birds sit on high voltage

power lines without getting electrocuted

it is not uncommon for a character in

the movies to end up with a blackened

face and head full of frizzy hair

if they come in contact with electricity

this makes for a good gag on screen

however this will end up killing us in

real life unless if we are birds

birds have no problem sitting unruffled

on the high voltage power lines

[Music]

electricity is the movement of electrons

the movement of electrons through a

device like our tv

is what gives it the energy to display

images and produce sound

the electrons are essentially being

pulled from the ground by the power

station

they move through the power lines

through our tv

and eventually they make their way back

into the ground

from where they came this creates a

closed loop

which is required for electricity to

flow

the other thing electrons need in order

to move is motivation

or more specifically a difference in

what's called

electrical potential

when a bird is perched on a single wire

its two feet are at the

same electrical potential so the

electrons in the wires have no

motivation to travel through the bird's

body

no moving electrons means no electric

current

the bird is safe for the moment anyway

if that bird stretches out a wing or a

leg

and touches a second wire especially one

with a different electrical potential

it will open a path for the electrons

right through the bird's body

there are other perils for our feathered

friends

the wooden pole supporting the wires is

buried deep in the ground

so it will also be dangerous for a bird

to sit on the wire

and touch the pole

[Music]

this is the problem that we encounter if

we touch live wires

since we are almost always in contact

with the ground

our bodies turn out to be excellent

conductors of electricity

and the electrical current will happily

use them to complete a closed

path to flow from high potential which

is the wire

to low potential which is the ground

electricity is the movement of electrons

electrons create

charge which we can harness to do work

our phone our light bulbs our television

and many other gadgets and machines all

harness the movement of the electrons in

order to do work

they all operate using the same basic

power source

electricity

the three basic principles for this

module can be explained using electrons

or more specifically the charge they

create

voltage current and resistance

voltage is the difference in charge

between two points

current is the rate at which charge is

flowing

resistance is the tendency of materials

to resist the flow of charge

so when we talk about these values we

are really describing the movement of

charge

and the behavior of electrons

a circuit is a closed loop that allows

charge to move from one place to another

components in the circuit allow us to

control this charge

and use it to do work through machines

or any output

anyway we will be talking more about

circuits

in a separate video

[Music]

george ohm was a bavarian scientist who

studied electricity

ohm starts by describing a unit of

resistance

that is defined by current and voltage

so let's start with voltage and go from

there

we define voltage as the amount of

potential energy

between two points on a circuit one

point has

more charge than another this difference

in charge between the two points

is called voltage it is measured in

volts

which technically is the potential

energy difference between

two points that will impart one joule of

energy

per column of charge that passes through

it

the unit volt is named after the italian

physicist

alessandro volta who invented the first

chemical battery

voltage is represented in equations and

schematics by the letter v

when describing voltage current and

resistance

a common analogy is a water tank

in this analogy charge is represented by

the amount of water

voltage is represented by the pressure

of water

and current is represented by the flow

of water

consider a water tank at a certain

height above the ground

at the bottom of this tank there is a

hose the pressure at the end of the hose

represents

voltage the water in the tank represents

charge

the more water in the tank the higher

the charge

the more pressure is measured at the end

of the hose

likewise the less water in the tank the

lower the charge

the less pressure is measured at the end

of the hose

we can think of this tank as a battery a

place where we store

a certain amount of energy and then

release it

if we release a certain amount of water

from the tank

the pressure created at the end of the

hose goes down

we can think of this as decreasing

voltage

like when a flashlight gets dimmer as

the batteries run down

there is also a decrease in the amount

of water that will flow through the hose

less pressure means less water is

flowing

which brings us to current

voltage can be generated by means other

than rubbing certain types of materials

against each other

chemical reactions like batteries

radiant energy

like solar cells and the influence of

magnetism on conductors

like generators are a few ways in which

voltage may be produced

for now we won't go into detail as to

how each of these voltage sources

works it is more important that we

understand

how voltage sources can be applied to

create charge flow

in an electric circuit

let's take this as a symbol for a

chemical battery

all right since we're done with voltage

let's talk about

current

as long as the battery continues to

produce voltage and

the continuity of the electrical path

isn't broken

charge carriers will continue to flow in

the circuit

we can think of the amount of water

flowing through the hose from the tank

as current the higher the pressure the

higher the flow

and vice versa following the metaphor of

water moving through a pipe

this continuous uniform flow of charge

through the circuit

is called the current

so long as the voltage source keeps

pushing in the same direction

the charge carriers will continue to

move in the same direction in the

circuit

this single direction flow of current is

called a direct current

or dc

with water we would measure the volume

of the water flowing through the hose

over a certain period of time with

electricity

we measure the amount of charge flowing

through the circuit

over a period of time current is

measured in amperes

usually just referred to as amps

an ampere is defined as 6.241

times 10 to the 18th power electrons

or one column per second passing through

a point in a circuit

amps are represented in equations by the

letter i

the unit ampere represented by a capital

letter a

is named after andre marie ampere

a french physicist who made important

contributions

to the theory of electricity and

magnetism

let's say for instance that we have two

tanks

each with a hose coming from the bottom

each

tank has the exact same amount of water

but the hose on one tank is narrower

than the hose on the other tank

we measure the same amount of pressure

at the end of either hose

but when the water begins to flow the

flow rate in the tank with the narrower

hose

becomes lesser than the one with the

wider hose

in electrical terms the current through

the narrower hose

is less than the current through the

wider hose

if we want the flow to be the same

through both hoses

we have to increase the amount of water

which is the charge

in the tank with a narrower hose this

increases the pressure

or the voltage at the end of the

narrower hose

pushing more water through the tank this

is analogous to an

increase in voltage that causes an

increase in

current

now we're starting to see the

relationship between voltage and current

but there is a third factor to be

considered here

the width of the hose in this analogy

the width of the hose is the resistance

this means we need to add another term

to our model

water equals charge measured in columns

pressure equals voltage measured in

volts

flow equals current measured in amperes

or amps for short

and hose width equals resistance

now let's proceed to resistance

[Music]

consider again our two water tanks

one with a narrow hose and one with a

wide hose

it stands to reason that we can't fit as

much

volume through a narrow hose than a

wider one

the same pressure

this is resistance the narrow hose

resists the flow of water through it

even though the water is at the same

pressure as the tank with the wider hose

[Music]

in electrical terms this is represented

by

two circuits with equal voltages and

different resistances

the circuit with a higher resistance

will allow

less charge to flow meaning the circuit

with higher resistance has less current

flowing through it

this brings us back to georgeon om

defines the unit of resistance of one

ohm

as the resistance between two points in

a conductor

where the application of 1 volt will

push 1

ampere recall that an ampere

is equal to 6.241

times 10 raised to the 18th power

electrons

this value is usually represented in

schematics

with the greek letter omega and

pronounced om

different materials have different

amounts of resistance

conductors have very little resistance

and therefore allow more charges to pass

through

insulators are materials that have very

high resistance

and therefore the flow of charges would

be difficult

the length and thickness of the

conducting wire are factors that affect

resistance encountered by current the

longer the wire

the greater will be its resistance the

greater the cross sectional area

which is a measure of the thickness of

the wire the lower will be its

resistance

the resistance of an object also changes

when the object becomes wet

dry human skin for instance has a

resistance of 100

000 ohms but when it gets wet

its resistance is reduced to 1000 ohms

that is why it is important to use dry

hands

when plugging an electrical appliance to

reduce

any chances of getting a lot of current

if an accident occurs

electric charges can be made to move

through a conducting material

the electric charges are the electrons

of the conducting material

materials such as copper steel

and aluminum have a lot of loosely held

electrons which makes them good

conductors of electricity

current is a measure of the number of

charges passing through a cross section

of a conductor on a given time

what is the direction of current a

battery has

terminal marks positive or plus and

negative

or minus the plus sign indicates

surplus or excessive charge

and the minus sign means deficiency

the movement of charges from the

positive side of the battery

to the negative side is called

conventional current

or simply current however

this is not the actual motion of

electrons in a circuit

the direction of the flow of electrons

is from the negative terminal

to the positive terminal this is called

electron current the direction of

current

does not affect what the current does

because electric current is composed of

individual

charge carriers flowing in unison

through a conductor by moving along and

pushing on the charge carrier's head

the amount of flow throughout a single

circuit

will be the same at any point if we were

to monitor

a cross section of the wire in a single

circuit

counting the charge carriers flowing by

we would notice

the exact same quantity per unit of time

as in any other part of the circuit

regardless of conductor length

or conductor diameter if we break the

circuit's continuity at any point

the electric current will cease in the

entire loop

and the full voltage produced by the

battery

will be manifested across the brake

between the wire ends that used to be

connected

an ammeter measures electric current

because the device measures how much

charge flows in a certain cross-section

at the given time

it has to be connected in series take

note how the positive and negative signs

of the ammeter

and the terminals of the battery are

oriented

[Music]

energy is needed to make the charges

move

in the previous module we learned that

when work is done on an

object energy is transferred

the voltage of a battery does the work

on charges to make them move

batteries are energy sources the

chemical

energy in the battery is transformed to

electrical energy

this electrical energy moves the charges

in a circuit

the work done on the charges as it

passes through a load

is measured as the voltage across the

load

a voltmeter measures voltage the

voltmeter

must be connected parallel or across the

load

the positive terminal of a voltmeter is

connected to the positive terminal

of the bulb while the negative terminal

is connected to the negative terminal of

the bulb

now how are these three related let's

start first with the relationship

between

voltage and current

voltage and current are two fundamental

quantities in electricity

voltage is the cause and current is the

effect

the higher the voltage the higher the

current

thus they are directly proportional

on the other hand the relationship of

resistance and current

is inversely proportional the lower the

resistance

the higher the current

now let's wrap things up electricity

is the movement of electrons electric

charges are the electrons of the

conducting materials

voltage is the difference in charge

between

two points current is the rate at which

charge is flowing and resistance

is the tendency of materials to resist

the flow of charge

or current that's all for now

stay tuned for our next video where we

will be discussing

how current voltage and resistance

affect each other through the ohm's law

see you on our next video and don't

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