4A5 Electrical Potential Flashcards
Explain the sources and processes required to generate electrical potential and electromotive force. (58 cards)
Define:
Electrical potential
It is the potential energy per unit charge at a point in an electric field.
Electrical potential is measured in volts (V).
Fill in the blank:
A ______ converts chemical energy into electrical energy.
battery
Batteries store chemical energy for direct current (DC) applications.
Define:
Electrode
Conductor that allows electrical current to enter or leave a device or medium, such as a battery or electrochemical cell.
It can be either an anode or a cathode.
What is the purpose of a battery electrolyte?
It allows the flow of ions between electrodes to sustain chemical reactions.
Common electrolytes include sulfuric acid in lead-acid batteries.
What is a redox process?
It involves two simultaneous reactions: oxidation, where a substance loses electrons, and reduction, where a substance gains electrons.
This process is crucial for chemical reactions, energy storage in batteries, and electrochemical applications.
Fill in the blank:
In a battery, the anode electrode is where _______ occurs.
oxidation
The anode releases electrons during oxidation.
What is the role of the cathode in a battery?
It is the electrode where reduction occurs, and electrons flow toward it during discharge.
In rechargeable batteries, the cathode and anode switch roles during charging.
Fill in the blank:
In a zinc-carbon battery, zinc serves as the _______, undergoing oxidation by releasing electrons.
anode
The zinc atoms lose electrons, forming zinc ions (Zn²⁺) and providing current flow.
What is a lead-acid battery?
A rechargeable battery that uses lead and lead dioxide plates submerged in sulfuric acid.
Common in cars.
Define:
Dry cell
Type of battery with a paste electrolyte instead of liquid.
Alkaline batteries are common examples.
Why are alkaline batteries preferred for portable electronics?
- Lightweight
- Stable voltage
- Long shelf life
They are more environmentally friendly than older battery types.
What happens when you connect two batteries in parallel?
The total voltage remains the same, but the current capacity increases.
Parallel connections are ideal for extending battery life.
How would you connect batteries to increase electrical potential in a circuit?
Connect them in series.
In series, the voltages of the batteries are summed.
How does temperature impact battery performance?
High temperatures shorten battery life, while low temperatures reduce performance and efficiency.
Lithium-ion batteries are sensitive to temperature changes.
Describe how a flashlight battery provides electrical potential.
By converting chemical energy into electrical energy to power the bulb.
Flashlights often use dry cell batteries.
What is the purpose of a salt bridge in a battery?
It maintains electrical neutrality by allowing the flow of ions between the two half-cells.
It prevents the accumulation of charge that would stop the reaction.
Fill in the blank:
In a rechargeable battery, energy is supplied to _______ the chemical reactions, restoring the battery’s capacity.
reverse
This reversal restores the original chemical composition, allowing the battery to store and release energy again.
What happens when a battery’s chemical reactants are fully consumed?
The battery stops generating electrical energy, as no further redox reactions can occur.
This is why disposable batteries eventually lose their charge and must be replaced.
True or false:
Photocells generate electrical potential by converting heat into electricity.
False
Photocells convert light, not heat, into electricity.
What are the main components of a photocell?
- Semiconductor layer
- Electrodes
- Encapsulation layer
- Anti-reflective coating
Photocells are also known as photovoltaic cells.
Semiconductor layer: Absorbs light and generates electron-hole pairs.
Electrodes: Collect the generated current.
Encapsulation layer: Protects the cell from environmental damage.
Anti-reflective coating: Increases light absorption efficiency.
Why can’t a solar panel generate electricity in the dark?
Photocells require light to release electrons and produce current.
Solar panels are ineffective without light sources.
Describe a situation where a photocell could be more effective than a battery.
In outdoor applications with abundant sunlight, such as solar garden lights.
Photocells are renewable but weather-dependent.
How does increasing the surface area of a photocell affect its efficiency?
It allows more light to be captured, generating higher electrical potential.
Surface design is critical for solar panel efficiency.
Define:
Electric generator
A device that converts mechanical energy into electrical energy through electromagnetic induction.
Generators are essential for producing electricity in both large power grids and portable applications.