Science Energy and Electricity Lecture Flashcards

Comprehensive practice questions covering energy types, efficiency, renewable and non-renewable sources, electric circuit laws (Ohm's Law), series and parallel circuits, and vehicle energy technologies.

How is energy defined in the lecture notes?

A measure of the ability to do work.

What does the Law of Conservation of Energy state?

Energy cannot be created or destroyed; it can only change form or be transferred, meaning the total energy before and after any process remains the same.

What is the difference between energy transformation and energy transfer?

Energy transformation is when energy changes from one form to another, while energy transfer is when energy moves from one object to another without changing its type.

What is the definition of chemical energy?

Energy stored in chemical bonds, such as in batteries, food, and chemical reactions.

What is elastic potential energy?

Energy stored in an object that has been compressed or stretched, such as a rubber band.

According to section 1.1 of the notes, what is the energy efficiency formula?

$$\frac{\text{useful energy input}}{\text{energy output}} \times 100$$

How is gravitational potential energy defined?

Energy stored in an object that has been raised to a higher point.

How is heat energy measured?

As the change in temperature of an object, occurring in the form of vibrating particles in solids, liquids, and gases.

What occurs every time energy changes form?

Some energy is lost as waste energy.

Why is energy efficiency always less than 100%?

Because no device or process can completely eliminate energy loss.

How does lubrication help reduce energy loss?

It reduces friction between moving parts.

What is the function of insulation in homes and devices?

It prevents heat loss.

What are the characteristics of renewable energy sources?

They are naturally made, environmentally-friendly, and infinite.

What causes electrons to move in solar panels to produce electrical energy?

Photons in the sunlight.

How is electricity generated from wind energy?

The movement of air particles spins a turbine, which is connected to an alternator.

From where does geothermal energy originate?

Heat inside the Earth's crust, which produces steam to spin a turbine.

What is biomass energy?

Energy from organic matter that stores chemical energy released when the material is burned.

What is the fourth step in the process of a coal-fired power station?

Steam moves under pressure and spins a turbine.

What happens to steam in a coal-fired power station after it spins the turbine?

It cools and condenses back into water so it can be reused.

What environmental impact is caused by sulfur oxide and nitrogen dissolving in rainwater?

The formation of acid rain.

What are the three fossil fuels mentioned in the notes?

Crude oil, natural gas, and coal.

How do gases like $CO_2$ contribute to the greenhouse effect?

They trap heat in the atmosphere.

What are the three types of consideration in energy production?

Economic (cost), Technological (efficiency and waste reduction), and Environmental (impact on people and environment).

What three components must be included in an electric circuit?

An energy source (battery or generator), components that use electrical energy, and wires to connect everything in a continuous loop.

What happens in an open circuit?

Electricity cannot flow because there is a gap or an open switch.

Into what forms can a load convert electrical energy?

Light energy (bulb), kinetic energy (motor), or heat energy (heater).

What is voltage?

The electrical potential energy difference between two points in a circuit, with the unit volt ($V$).

What can happen if there is too much voltage in a circuit?

It can cause components to overheat or blow off.

How is current defined and what is its symbol in formulas?

A measure of the flow of charged particles (electrons), represented by the symbol $I$.

What is resistance?

The opposition to the flow of current occurring because wires and components slow down the movement of electrons.

Why are power cords coated in plastic?

Plastic is an insulator that does not allow the flow of charged particles, preventing electric shocks.

What does Ohm's law demonstrate?

The current through a conductor between two points is directly proportional to the voltage across the two points.

What is the formula for Voltage ($V$) according to Ohm's law?

$$V = I \times R$$

What is the formula for Resistance ($R$) according to Ohm's law?

$$R = \frac{V}{I}$$

How must an ammeter be connected in a circuit?

In a series circuit, with the red terminal to positive ($+\text{}$) and black to negative ($-\text{}$).

How is a voltmeter connected in a circuit?

In a parallel circuit across a single component at a time.

What defines a parallel circuit?

A circuit in which all components are connected between the same points in branches, allowing current to divide into more than one path.

What is the disadvantage of a series circuit regarding component failure?

If one component fails, the entire circuit stops working.

How does voltage behave across components in a series circuit?

The voltage across components adds up to the total voltage supplied by the battery.

How does current behave in a parallel circuit?

The current in each component adds up to the total current in the main branch containing the battery.

How is total resistance calculated in a parallel circuit?

The total resistance is the reciprocal of the sum of the reciprocals of resistance: $\text{Total resistance} = \frac{1}{\frac{1}{R_1} + \frac{1}{R_2} + ...}$

What formula is used to calculate the annual running cost of an appliance?

$$\text{Annual running cost} = \text{energy consumption (kWh)} \times \text{energy tariff (dollars/kWh)}$$

What is the purpose of energy rating labels on appliances?

They display estimated annual energy consumption and star ratings to encourage consumers to buy energy-efficient products.

How is the effectiveness of insulation measured?

Using the R-value; a higher R-value indicates better insulation.

What is temperature inversion?

A phenomenon where warm air traps cool air below, preventing pollutants from escaping and causing smog.

Why do passenger cars in Australia use more fuel than those in Europe or the US?

Larger cars, heavier vehicles, and fewer fuel-efficient or diesel options.

What are Battery Electric Vehicles (BEVs)?

Vehicles that run entirely on batteries powering electric motors, producing no tailpipe emissions while driving.

What is the chemical equation for a hydrogen fuel-cell?

$$\text{Hydrogen} + \text{Oxygen} \rightarrow \text{Water} + \text{Energy}$$

What are the two ways to produce hydrogen for fuel-cell vehicles?

Electrolysis (splitting water using electricity) and Steam reforming (using methane, which produces $CO_2$).

What are the main causes of energy loss in electric vehicles (EVs)?

Charging losses, motor inefficiency, and electrical accessories.