Electricity

Question 0

Effects of Resistance in Circuits

Answer 0

Length: longer wire, greater resistance

Temperature: Hotter wire, greater resistance

Thickness/Diameter: Thicker wire, lower resistance

Type of material

Question 1

Potential Difference - Water Analogy

Answer 1

Energy of falling water used to push waterwheels because water above wheel has greater gravitational potential energy than it does below wheel. Steady supply of water is needed to keep wheel spinning. As water’s pumped to its original position, its gravitational potential energy also increase to original amount.

Similarly, there’s potential difference between 2 terminals of an electric cell. Electrons leave negative terminal w/ electric potential energy to operate a motor. Electrons return to positive terminal w/ less electric potential energy since some energy was used to run the motor. Once inside cell, chemical reactions ‘re-energize’ electrons & send them out megative terminal again.

Electric cell acts like the water pump.

Question 2

Current

Answer 2

Rate of charge flow

Question 3

Potential Difference

Answer 3

Difference of potential energy when measure of work per unit charge between 2 points in a circuit.

Question 4

Loads in Series

Answer 4

More bulbs, dimmer bulbs.

Same amount of energy has to be distributed throughout even more loads, each with less energy.

Same voltage applied over greater resistance, decreasing the current / brightness.

Question 5

Loads in Parallel

Answer 5

More bulbs, same brightness.

Different branches for electrons to flow through to get to each load with each load having the same amount of voltage so it wouldn’t make a difference.

Question 6

What remains all the same in Series

Answer 6

Current (I)

Question 7

What remains the same in Parallel?

Answer 7

Voltage (V)

Question 8

Law of Electric Charge

Answer 8

Like charges repel, unlike charges attract, charged objects attract neutral objects.

Question 9

Objects that hold a charge

Answer 9

Combs, rulers, clothing, airplanes, clouds

Question 10

Objects that DO NOT Hold a Charge

Answer 10

Hair, rubber balloon

Question 11

Static Electricity

Answer 11

An imbalance of electric charge on the surface of an object.

Question 12

Current Electricity

Answer 12

The controlled flow of electrons through a conductor.

Question 13

Conductors

Answer 13

Material that allow electrons to flow through it

Ex: metals (silver, gold, aluminium, copper, iron)

Question 14

Semiconductors

Answer 14

Materials somewhere in between insulators & conductors

Ex: graphite-carbon, human body, damp skin, salt water, silicon, earth

Question 15

Insulator

Answer 15

Material that DOES NOT allow electrons to flow through

Ex: non-metals (oil, fur, wool, silk, rubber, glass, plastic, pure water, ebonite, wax, paper, wood)

Question 16

Pros: Hydro-Electric

Answer 16

Doesn’t produce pollution

Uses vast amount of concrete, steel, specialized machinery, fossil fuel resources

Long-lasting, electricity produced at a constant rate

Question 17

Pros: Tidal

Answer 17

Renewable, emission-free, high efficiency

Question 18

Pros: Thermal

Answer 18

Loads of employment opportunities

Question 19

Pros: Wind

Answer 19

Significantly cheaper compared to other methods

Short transmission lines, minimizing electricity loss

Question 20

Pros: Sunlight

Answer 20

Long-lasting, maintenance- free

Can be operated independently of the power grid or not

Question 21

Cons: Hydro-Electric

Answer 21

Uses dams, changing the way water flows

Disrupts migration of fish and flood large areas of land

Very expensive

Limited suitable locations available

Question 22

Cons: Tidal

Answer 22

Built near coastlines that experience significant changes in tide

Question 23

Cons: Thermal

Answer 23

Burning of fossil fuels contribute to climate change

Increase Earth’s temperature due to radiation of carbon dioxide

Produces air pollution and destroys natural habitats

Question 24

Cons: Wind

Answer 24

Noisy, dangerous to birds Difficult to generate steady electricity supply at particular locations

Question 25

Cons: Sunlight

Answer 25

30% efficient at converting Sunlight Expensive Time-consuming to produce elctricity

Question 26

Electric Cell

Answer 26

Produces small quantity of electrical energy, useful for portable electrical devices Has 2 electrodes (conductors) called an electrolyte 1 electrode can be positive and the other, negative When ends are joined to conducting wires of a circuit, electrons begin to flow through from one electrode to the other Electrons in electrolyte are repelled by negative electrode and attracted to the positive electrode Electrons pass from negative to positive terminal All electric cells contain chemicals that are toxic to the environment, could damage naturals surroundings - should be properly recycled

Question 27

Fuel Cell

Answer 27

Special kind of electric cell that requires a continuous supply of fuel (i.e., hydrogen, oxygen) to provide electrical energy Any waste products are removed during the process Can operate longer than conventional/typical electric cell Hydrogen used in most fuel cells must be removed from compounds rich in hydrogen i.e.m fossil fuels. This process uses lost of energy creating pollution & contributes to climate change

Question 28

Uses of Static Electricity: Electrostatic Applications Paint Sprayers

Answer 28

Reduce amount of wasted paint, efficiently paint objects especially curved shaped Paint given a charge as it leaves nozzle of sprayer and object to be painted is given opposite charge. Charged paint particles attract to object, minimizing amount of wasted paint & ensuring object receives an even coat of paint

Question 29

Uses of Static Electricity: Electrostatic Applications Precipiators

Answer 29

Remove particles from air, filter particles from smokestack emissions When smoke passes through negatively charged plates, particles in smoke become negatively charged by conduction. Particles then pass between positively charged plates, which they stick to, due to attraction of opposite charges. Particles fall onto collection plate, safely removing them.

Question 30

Uses of Static Electricity: Electrostatic Applications Lifting Apparatus

Answer 30

Make copies of footprints (for investigation) Special film/foil placed over footprint, black side placed over footprint. Film is then electrostatically charged, dust & dirt particles from footprint are attracted to black side Dust particles jump off floor onto black film, revealing details of footprint

Question 31

Uses of Static Electricity: Electrostatic Applications Speakers

Answer 31

Constructed of 3 thin layers, outer 2 called stators are fixed in place Inner layer is flexible film called, diaphragm which vibrates to produce sound Accomplished using principles of induction and law of electric charges Inner surface given permanent electrical charge Audio transformed used to induce opposite charges in 2 outer plates. Causes diaphragm to move as it's attracted to 1 outer plate and repelled by the other. Audio transformer then rapidly induces static charges in outer plates to reverse themselves. This causes diaphragm to move toward opposite outer plate. Reversing of charges on outer plates happens repeatedly and at variable frequencies causing diaphragm to rapidly vibrate back and forth between plates, producing sound waves in air

Question 32

Electric Discharge

Answer 32

Rapid transfer of electrons from one object to another When 2 objects that have a charge imbalance are brought close together or some in contact, electrons are transferred from one object to another. Electrons always move from object w/ more negative charge to object w/ less negative charge.

Question 33

Lightning

Answer 33

When water droplets in clouds move past one another, they become charged. Electrons are transferred from rising water molecules to falling water droplets. Negatively charged water molecules collect at bottom of cloud. Excess negative charge at bottom of cloud repels electrons at Earth's surface. Electrons move away from area on Earth's surface near cloud, causing it to become positively charged. Results in a charge imbalance.

Question 34

Alternating Current AC

Answer 34

Flow of electrons that alternates in direction in an electric circuit, produced by electric cells

Question 35

Direct Current DC

Answer 35

Flow of electrons in one direction through an electric circuit, produced in generating plants

Question 36

Basic Components of an Electric Circuit

Answer 36

Load - converts electrical energy into other forms of energy Switch - controls flow of electrons by opening/closing circuit Electric Cell/Battery - Energy source

Question 37

3 ways to reduce electricity consumption at home

Answer 37

Turn off appliances & lights whenever you leave home Unplug chargers when not charging Cutting heating needs, insulate walls and ceilings instead Switching to solar energy