37 Questions
What is the defining characteristic of an insulator in terms of the number of free electrons in its valence shell?
Five to eight free electrons in its valence shell
Why are rubber and its variants commonly used as insulators around copper wiring?
Because rubber tightly binds the electrons within the material, making them unavailable for conduction
Which of the following materials is NOT a common insulator?
Copper
What is the distinguishing feature of a semiconductor in terms of the number of free electrons in its valence shell?
Two to four free electrons in its valence shell
Which of the following elements is a compound rather than an element, but still classified as a common semiconductor material?
Gallium arsenide (GaAs)
What property of a pure silicon crystal prevents electricity from flowing through it?
Low electron mobility
What effect do the strong covalent bonds in a pure silicon crystal have on its ability to conduct electricity?
They decrease its conductivity
Which process is responsible for changing the behavior of silicon to allow conduction?
Doping
Why do neither silicon nor germanium conduct electricity in their pure form?
Due to the number of valence electrons and strong covalent bonds
What type of material is nearly an insulator and allows very little electricity to flow through it?
Semiconductor
What material is most suitable for a rubbing connection with commutators or slip rings used in generators and alternators?
Carbon
Which non-metal solid is mentioned as having significance as a conductor?
Carbon
What creates ions in some liquids when current is passed through them?
Electrodes of the liquid create current passing through the electrolyte
What are groups of atoms called that are ionized in a liquid?
Molecules
Which type of ions move in opposite directions in a liquid?
Negatively charged ions and Positively charged ions
What is the defining characteristic of an insulator?
It inhibits the flow of electrons
How do insulators differ from conductors in terms of electron flow?
Insulators do not allow the flow of electrons
Why does a positive ion in an insulator try to attract electrons from surrounding atoms?
Because it has more protons than electrons
Which material is most commonly used as an insulator?
None of the above
What happens when a positive force is applied to an insulator?
The atom becomes a positive ion
In which form does carbon act as an electrical insulator?
Diamond
Which element has the most common semiconductor element in the world?
Silicon
Why are metals good conductors of electricity?
Because they have 'free electrons'
Which material conducts electricity but not as well as metals like copper or gold?
Graphite
What atomic structure allows silicon and germanium to have good semiconductor properties?
4 electrons in their valence shell
Which type of compound dissociates completely into charged atoms or molecules when dissolved in water?
Compounds with strong conductivity
Why are compounds with weak conductivity considered poor conductors of electricity?
They dissociate slowly in water
What characterizes the atoms of commonly used conductors such as copper, silver, gold, and aluminium?
They have a single valence electron very loosely bound to the atom
What type of compound is acetic acid in terms of electrical conductivity?
Weak electrolyte and poor conductor
Why do compounds with strong conductivity have greater conductivity when the concentration of ions is higher?
The greater the concentration of ions, the greater the conductivity
What is the common misconception about the conductivity of water?
Pure water is a good conductor of electricity due to its natural composition.
What happens to the conductivity of compounds when they become liquid at high temperatures?
They become conductive as the cations and anions begin to flow.
Why does ethanol behave as an insulator?
As a result of its molecular composition and lack of ions in solution.
What makes potassium chloride (KCl) a good conductor when dissolved in water?
Its dissociation into ions when dissolved in water allows it to conduct electricity.
Why do non-ionic compounds not conduct electricity?
They do not dissociate into ions when dissolved in water.
How can a simple circuit with a light bulb be used to test the conductivity of aqueous compounds?
The light bulb will only turn on if the compound is a good conductor.
What defines an electrolyte?
Any liquid or gel which contains ions and can be decomposed by electrolysis.
Learn about the electrical conductivity of acetic acid, the main component of vinegar, which is a compound of carbon, hydrogen, and oxygen and is a poor conductor of electricity. Understand how molecular structure affects the ability of compounds to conduct current.
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