52 Questions
What does the voltage between two bodies measure?
The difference in potential between the two bodies
In a circuit with steady EMF, what effect does doubling the resistance have on the current?
Halves the current
How does resistance change with the length of a conductor?
Directly proportional to the length
What is the unit of electrical resistance?
Ohm
What factors control the resistance of an object?
Material, length, cross-sectional area, and temperature
According to Ohm's law, what is the relationship between voltage, current, and resistance?
$V = IR$
What is the unit for the measurement of a material's ability to conduct current?
Siemens
What does G = 3 S mean?
Conductance of 3 siemens
What did Edison discover when he connected the filament battery and allowed the filament to heat?
The ammeter in the filament-plate circuit deflected and remained deflected.
What happens to the electrons boiled from the heated filament?
They are attracted to the positively charged plate.
Why did Edison do little with the discovery of electron flow across the gap between the filament and plate?
Because it did not solve the soot problem caused by the incandescent light bulb.
What does the application of basic law 'unlike charges attract' refer to in the context of Edison's circuit?
The attraction between the electrons and the positively charged plate.
In the context of electrolytes, which type of solution exhibits the strongest conductivity?
Soluble salt solution (NaCl)
What type of substances are able to conduct ionically and are known as electrolytes?
Ionic compounds
When positive and negative electrodes are placed in an electrolyte, what naturally occurs?
The ions are repelled by the electrodes and move freely in the electrolyte
What type of substances are most commonly known as electrolytes?
Acid, alkali, or salt solutions
In the context of conducting electricity through an ionic solution, what allows the ions to carry the electric current?
Their ability to move freely in the solution
In which order do these materials, in terms of conductivity, appear from best to worst?
Silver, gold, aluminium, copper
What is the material most commonly used as a conductor?
Copper
What is the speed at which electricity reaches the other end of a conductor?
At the speed of light
In which way does electricity conduct through solids?
Movement of electrons
What initiates a domino effect with electrons jumping from atom to atom in a solid conductor?
Application of EMF
Which of the following compounds is a weak electrolyte and a poor conductor of electricity?
Acetic acid
What type of compounds dissociate completely into ions when dissolved in water, and thus have strong conductivity?
Table salt
Which material is characterized by atoms with a single valence electron very loosely bound to the atom, making it a commonly used conductor?
Copper
Compounds that dissociate only partially in water are weak electrolytes and poor conductors of an electric current. Which of the following falls into this category?
Vinegar
Which compound dissociates into positively charged sodium and negatively charged chlorine ions in water, demonstrating strong conductivity?
Sodium chloride
What happens when ions reach the electrodes in a galvanic cell?
They give or receive electrons, contributing to the electron transfer of charge through the solid conducting circuit external to the electrolyte
What happens when a gas is ionized?
Its resistance is markedly decreased
What did Thomas Edison discover as he looked for ways to keep soot from clouding his incandescent light bulb?
The principle of thermionic emission
What occurs across the gap of spark plugs in piston engines?
Ionization
In a galvanic cell, where do ions either give or receive electrons, contributing to the electron transfer of charge?
At the electrodes
Which materials in the triboelectric series are likely to produce the highest voltage when rubbed together?
Walking across carpet and chair padded with polyurethane foam
What is the relationship between materials' position on the triboelectric series and their charge?
Materials higher in the series become positively charged, and those lower become negatively charged
How does the relative humidity affect electrostatic voltages based on the information provided?
Higher humidity leads to lower electrostatic voltages
According to the information provided, what is the main factor that determines the voltage levels generated when two materials are rubbed together?
The materials' position on the triboelectric series
Who first discovered the relationship between attracting or repelling charged bodies, as mentioned in the text?
Charles A. Coulomb
What is the significance of carbon as a conductor compared to copper?
Carbon has a higher resistance than copper
What creates ions when current is passed through some liquids?
Atoms of liquid or gas gaining or losing an electron
In a liquid, what is ionized when current is passed through?
Molecules
In a galvanic cell, which direction do negatively charged ions move?
In the direction of the positively charged electrode
What type of battery is commonly manufactured from lead and lead dioxide?
Lead-acid battery
According to the electron theory, in which direction does the current flow?
From the negative terminal to the positive terminal
What is the unit of current?
Ampere
If 1 C flows through a circuit each second, what is the current?
1 ampere
What is the symbol for amperes?
I
According to the conventional current flow theory, in which direction does the current flow?
From the positive terminal to the negative terminal
What does 'I = 3 A' represent?
$3$ amperes of current
What is the abbreviation for ampere?
$A$
What does the symbol 'I' represent in electrical circuits?
Current
In which direction does a current flow when connected between the terminals of a power source according to the electron theory?
From negative terminal to positive terminal
'Electric current flow conventions' are based on which theory that describes how current flows?
'Conventional current flow theory'
Study Notes
Electrical Properties and Conduction
- Voltage between two bodies measures the potential difference between them.
- Doubling the resistance in a circuit with steady EMF halves the current.
- Resistance increases with the length of a conductor.
- The unit of electrical resistance is the ohm (Ω).
- Factors controlling resistance include the object's material, length, and cross-sectional area.
Ohm's Law and Conductivity
- Ohm's law states that voltage, current, and resistance are related by the equation V = IR.
- The unit of a material's ability to conduct current is the siemens (S).
- G = 3 S means that the material's conductivity is 3 siemens.
Edison's Discovery and Electrolytes
- Edison discovered electron flow across the gap between the filament and plate when he connected the filament to a battery.
- The electrons boiled from the heated filament move towards the plate.
- Electrolytes are substances that can conduct ionically and include solutions like acid and bases.
- In an electrolyte, positive and negative electrodes naturally attract ions.
- Solutions exhibiting the strongest conductivity are typically acids and strong bases.
Conductivity and Ionization
- Ions carry electric current in an ionic solution.
- Substances like copper are commonly used as conductors due to their loose valence electrons.
- Electricity conducts through solids by a domino effect of electrons jumping from atom to atom.
- Compounds that dissociate completely into ions, like sodium chloride, have strong conductivity.
- Weak electrolytes, like sugar, dissociate only partially in water and are poor conductors.
Galvanic Cells and Electrostatics
- In a galvanic cell, ions give or receive electrons at the electrodes, contributing to the electron transfer of charge.
- When ions reach the electrodes, they either give or receive electrons.
- Ionization occurs when a gas is ionized.
- The triboelectric series determines the relative voltage generated when two materials are rubbed together.
- The main factor determining voltage levels is the relative humidity.
History and Theories
- Thomas Edison discovered the phenomenon of thermionic emission.
- The relationship between attracting or repelling charged bodies was first discovered by Charles Coulomb.
- According to the electron theory, current flows from negative to positive.
- The conventional current flow theory describes current flowing from positive to negative.
- Electric current flow conventions are based on the conventional current flow theory.
Test your knowledge about Thomas Edison's discovery of electrical current flowing across a gap between a filament and a plate. Explore the details about how Edison reasoned the presence of electrical current in the circuit.
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