S13Phys2BaLec26A

# For most metals as you increase the temperature the

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For most metals, as you increase the temperature the resistivity of the metal increases. The following equation takes temperature into account for resistivity: where ρ is the resistivity at some temperature T. ρ o is the resistivity at some reference temperature T o . α is the temperature coefficient of resistivity. T o is usually taken to be 20 o C.

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Ohm’s Law Ohm’s Law is not really a law in the technical sense. It merely defines the resistance for certain materials. Certain materials obey Ohm’s Law, these are called ohmic materials. There is a linear relationship between current and electric potential. Certain materials do not obey Ohm’s Law, these are called nonohmic materials.
Clicker Question 26A-1 Which one of the following statements concerning conventional current is true? A) The conventional direction of current is the hypothetical direction of movement of positive charges through the wires of an electric circuit. B) The conventional direction of current is the direction of movement of electrons through the wires of an electric circuit. C) The conventional current is the one that moves in a dc circuit and an unconventional current is one that moves in an ac circuit. D) The conventional direction of current is always a clockwise movement around a circuit.

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Clicker Question 26A-2 Which pair of terms correctly fills the blanks in the following sentence? ________ is a property of an object while ________ is a property of a type of material. A) resistivity, conductivity. B) current, resistance. C) resistance, current. D) resistance, resistivity.
For Next Time (FNT) Finish reading Chapter 26 Keep working on the homework for Chapter 25
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