Electricity

What do electricity and magnetism have in common?

Both involve forces caused by charged particles and are closely related through electromagnetism.

What is the major difference between electricity and magnetism?

Only certain materials can be magnetized, while electric charge exists in all matter.

What causes magnetic fields?

Moving electric charges.

What causes electric fields?

Electric charges.

Would lightning affect a compass?

Yes, lightning produces a strong magnetic field that could temporarily disturb the compass needle.

Why does lightning create a magnetic effect?

Lightning is a massive flow of electric current, and electric currents create magnetic fields.

What is an electromagnet?

A magnet created by electric current flowing through a wire.

How can you create a magnetic field with wire and a battery?

Wrap wire into a coil and connect it to a voltage source so current flows through it.

How does increasing current affect an electromagnet?

It increases the strength of the magnetic field.

How does adding more wire loops affect an electromagnet?

It strengthens the magnetic field.

What is magnetic induction?

The process of generating electricity using a changing magnetic field.

How does magnetic induction work?

A moving magnetic field pushes electrons through a conductor to create current.

What is electromagnetic induction?

The generation of electric current from a changing magnetic field.

How does an electric motor work?

Electric current creates magnetic fields that cause motion.

What converts electrical energy into mechanical energy?

An electric motor.

What converts mechanical energy into electrical energy?

An electric generator.

How does an electric generator work?

A magnet moves near coils of wire, inducing electric current.

What is the main principle behind generators?

Magnetic induction.

Why is a generator described as a motor in reverse?

A motor uses electricity to create motion, while a generator uses motion to create electricity.

What was Edison’s main problem with the Pearl Street Power Station?

Direct current lost too much power over long distances.

Why does electricity lose energy during transmission?

Resistance in wires converts electrical energy into heat.

What are the three factors that determine wire resistance?

Length, thickness, and material.

How does wire length affect resistance?

Longer wires have greater resistance.

How does wire thickness affect resistance?

Thicker wires have lower resistance.

How does wire material affect resistance?

Some materials conduct electricity better and therefore have lower resistance.

What material is commonly used in power lines because of low resistance?

Copper.

What formula calculates electrical power?

Power = Voltage × Current.

What is Ohm’s Law?

Voltage = Current × Resistance.

What formula describes power loss in transmission lines?

Power loss = I²R.

How is the power loss formula derived?

Using P = IV and V = IR gives P = I(IR) = I²R.

Why does high current increase power loss?

Power loss depends on the square of the current.

How do power companies reduce power loss?

By increasing voltage and reducing current.

What is a transformer?

A device that changes voltage using magnetic induction.

How does a transformer work?

Current in one coil creates a magnetic field that induces current in another coil.

What are the two main parts of a transformer?

The primary coil and the secondary coil.

What is a step-up transformer?

A transformer that increases voltage.

What is a step-down transformer?

A transformer that decreases voltage.

How does a step-up transformer work?

The secondary coil has more loops than the primary coil.

How does a step-down transformer work?

The secondary coil has fewer loops than the primary coil.

Why does voltage increase with more coil loops?

More loops experience greater magnetic induction.

A transformer has 5 loops on the primary coil and 20 loops on the secondary coil. What type is it?

A step-up transformer.

Why do power plants step up voltage?

To reduce current and minimize power loss during long-distance transmission.

Why is voltage stepped down before electricity enters homes?

High voltages are dangerous and unsuitable for household appliances.

What voltage is typically generated at a power plant?

About 20,000 volts.

What voltage is commonly used in long-distance transmission lines?

Hundreds of thousands of volts, often around 345,000 volts.

What voltage usually reaches homes in the United States?

120 volts and 240 volts.

Why did Edison electrocute an elephant and promote the electric chair?

To scare the public about alternating current and discredit Tesla and Westinghouse.

What type of current did Edison support?

Direct current (DC).

What type of current did Tesla support?

Alternating current (AC).

Why is AC better for long-distance transmission?

AC voltage can be easily changed with transformers.

Why can’t power lines use a billion volts?

Extremely high voltages would ionize air, create arcing, and become unsafe and impractical.

What is electrical arcing?

Electricity jumping through air between conductors.

What happens at the power plant generator stage?

Mechanical energy spins a generator to produce electricity.

What happens at the power station stage?

Voltage is stepped up for efficient long-distance transmission.

What happens at the area substation stage?

Voltage is stepped down closer to regional distribution levels.

What happens at the distribution substation stage?

Voltage is reduced further for local neighborhoods.

What happens at the residential transformer stage?

Voltage is stepped down to safe household levels.

What type of energy usually spins a generator turbine?

Mechanical energy from steam, water, wind, or other moving sources.

What is alternating current (AC)?

Electric current that regularly reverses direction.

What is direct current (DC)?

Electric current flowing in one direction only.

Why are transformers ineffective with DC?

Transformers require changing magnetic fields, which DC does not provide continuously.

What is the electrical grid?

A network of power plants, transmission lines, and substations delivering electricity.

What are the three major electrical grids in the United States?

The Eastern Interconnection, Western Interconnection, and Texas Interconnection.

What is one problem with the U.S. electrical grid system?

Aging infrastructure.

What is another problem with the U.S. electrical grid system?

Limited connections between the three major grids.

Why can grid failures spread easily?

The grids are highly interconnected.

What is a blackout?

A large-scale loss of electrical power.

What causes heat in electrical wires?

Resistance to electron flow.

Why are high-voltage transmission lines efficient?

They reduce current and therefore reduce heat loss.

What is electrical resistance?

Opposition to the flow of electric current.

What is electric current?

The flow of electric charges through a conductor.

What is voltage?

The electrical potential difference that pushes charges through a circuit.

What unit measures current?

Amperes (amps).

What unit measures voltage?

Volts.

What unit measures resistance?

Ohms.

What unit measures power?

Watts.

How are electricity and magnetism connected?

A changing electric field creates a magnetic field, and a changing magnetic field creates an electric field.

What is the role of turbines in power generation?

They provide the mechanical motion needed to spin generators.

Why are generators essential in power plants?

They convert mechanical energy into electrical energy.

What type of current is produced by most large generators?

Alternating current.

What happens when a conductor moves through a magnetic field?

An electric current is induced in the conductor.

What scientist discovered electromagnetic induction?

Michael Faraday.

Why is copper commonly used in electrical systems?

It has low resistance and conducts electricity efficiently.

What is the relationship between current and power loss?

Higher current produces much greater power loss.

What is the relationship between voltage and current for a fixed power level?

Higher voltage allows lower current.

Why are substations important?

They safely control and distribute electrical voltage levels.

What is the purpose of insulators on power lines?

To prevent electricity from escaping into surrounding materials.

What materials are commonly used as insulators?

Rubber, glass, and ceramics.

What is the danger of overloaded electrical systems?

Excess heat can cause fires and equipment damage.

Why is AC current safer for grid transmission?

It works efficiently with transformers and long-distance transmission systems.

What is electromagnetic force?

The force produced by electric and magnetic fields.

What happens inside a transformer core?

A changing magnetic field transfers energy between coils.

Why are transmission towers spaced apart?

To safely support high-voltage power lines over long distances.

What is one advantage of underground power lines?

They are protected from weather damage.

What is one disadvantage of underground power lines?

They are expensive to install and repair.

What is the purpose of the residential transformer on utility poles?

To reduce voltage to safe levels for homes.

What is energy conservation in electrical systems?

Reducing waste and improving efficiency during electricity production and transmission.