In the context of science, what is the standard definition of energy?
Energy is defined as the ability to do work.
Which specific device is designed to convert electrical energy into thermal energy for household use?
Heating elements (such as those in a toaster or stove).
A _____ is a component that resists the flow of electrons, converting electrical energy into heat.
resistor
What is the relationship between the resistance of a wire and the amount of heat it produces?
The more resistance a wire has, the more heat it typically produces.
Term: Thermocouple
Definition: A loop of two wires made of different metals that converts heat directly into electricity.
The phenomenon where a small electric current is produced by heating the junction of two different metals is known as the _____.
Seebeck Effect
In a thermocouple, what happens to the electric current if the temperature difference between the junctions increases?
The electric current increases.
What is the primary advantage of using a thermocouple instead of a liquid thermometer for temperature measurement?
They are rugged and can measure extremely high temperatures where liquid thermometers would fail.
Term: Thermopile
Definition: A device consisting of several thermocouples connected in series.
A _____ is a device based on a thermopile that converts heat directly into electricity without any moving parts.
thermo-electric generator
Why are thermo-electric generators particularly useful in remote locations or space probes?
They are extremely reliable, low-maintenance, and do not require moving parts like turbines.
Term: Piezoelectric Effect
Definition: The relationship between mechanical pressure and electricity in certain crystals.
What happens to a piezoelectric crystal, such as quartz, when it is connected to a potential difference?
The crystal expands, contracts, or vibrates.
What occurs when a piezoelectric crystal is physically compressed or pulled?
A potential difference builds up on opposite sides of the crystal, acting as an energy source.
Which common household item uses a hammer slamming against a piezoelectric crystal to generate a high-voltage spark?
A barbecue spark lighter.
In a crystal microphone, how is sound converted into an electrical signal?
Sound pressure vibrates a piezoelectric crystal, which changes the voltage in the circuit.
What type of light bulb uses a high-resistance metal filament that glows when current passes through it?
Incandescent light bulb.
In a fluorescent bulb, what causes the phosphor coating to create visible light?
Electric current energizes a gas, emitting ultraviolet light that strikes the coating.
Term: Light-Emitting Diode (LED)
Definition: A solid-state electronic component that glows when electricity flows through it in one specific direction.
What are two advantages of LEDs compared to traditional incandescent bulbs?
They use a fraction of the power and have a much longer working lifespan.
Term: Photovoltaic (PV) Cell
Definition: A device made of semiconducting materials that converts light energy directly into electrical energy.
What happens at the atomic level when light strikes a photovoltaic cell?
The semiconductor material absorbs the light, breaking electrons loose so they can flow freely as current.
Which material is most commonly used as the semiconductor in photovoltaic cells?
Silicon
The South American fresh water eel generates electricity using specialized muscle cells called _____.
electrocytes
