QQuestionPhysics
QuestionPhysics
Choose suitable examples of materials and their uses in order to provide an illustrated explanation of the properties of the following: conductivity, resistivity, insulators and conductors, ohmic and non-ohmic conductors, capacitors acting as filters in AC circuits and semi-conductors.
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Step 1:: Introduction to Conductivity and Resistivity
\rho = \frac{1}{\sigma}
Conductivity and resistivity are properties that describe how easily electric current can flow through a material. Conductivity (denoted by σ) is a measure of a material's ability to conduct electric current, while resistivity (denoted by ρ) is a measure of a material's opposition to the flow of electric current. The relationship between conductivity and resistivity is given by:
Step 2:: Conductors and Insulators
Conductors are materials with high conductivity, meaning they allow electric current to flow easily. Examples of conductors include metals like copper, aluminum, and gold. Insulators, on the other hand, are materials with low conductivity, meaning they oppose the flow of electric current. Examples of insulators include materials like rubber, plastic, and glass.
Step 3:: Ohmic and Non-Ohmic Conductors
V = IR
Ohmic conductors follow Ohm's law, which states that the current through a conductor between two points is directly proportional to the voltage across the two points. This can be written as: where V is the voltage, I is the current, and R is the resistance. Non-ohmic conductors do not follow Ohm's law, meaning the current through the material is not directly proportional to the voltage. An example of a non-ohmic conductor is a diode.
Step 4:: Capacitors Acting as Filters in AC Circuits
Z = \frac{1}{2 \pi f C}
Capacitors are components in circuits that store electrical energy in an electric field. In AC circuits, capacitors can act as filters, allowing certain frequencies to pass through while blocking others. This is due to the fact that capacitors have an impedance, which is a frequency-dependent resistance. The impedance of a capacitor is given by: where Z is the impedance, f is the frequency, and C is the capacitance.
Step 5:: Semi-Conductors
Semi-conductors are materials that have properties between those of conductors and insulators. They have a low conductivity, but this conductivity can be increased by adding impurities, a process known as doping. Semi-conductors are used in a variety of applications, including transistors, solar cells, and LEDs.
Final Answer
Conductivity and resistivity are properties that describe how easily electric current can flow through a material. Conductors, such as copper and aluminum, have high conductivity and allow electric current to flow easily. Insulators, such as rubber and plastic, have low conductivity and oppose the flow of electric current. Ohmic conductors follow Ohm's law, while non-ohmic conductors do not. Capacitors can act as filters in AC circuits, allowing certain frequencies to pass through while blocking others. Semi-conductors have properties between those of conductors and insulators and are used in a variety of applications, including transistors, solar cells, and LEDs.
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