Lesson: Resistance and Resistivity of Conductors High School Physics

Physics

In this lesson, we will learn how to relate the dimensions of and the motion of free electrons through an object to its resistance.

Video

13:10

Sample Question Videos

02:14
02:15

Worksheet

Q1:

A wire made of an unknown substance has a resistance of 125 mΩ. The wire has a length of 1.8 m and a cross-sectional area of m². What is the resistivity of the substance from which the wire is made?

Q2:

A copper wire with a resistance of 12.8 mΩ has a cross-sectional area of m. Find the length of the wire. Use Ω⋅m for the resistivity of copper.

Q3:

The diagram shows two identical circuits. Each circuit’s conducting wire has had a section of it greatly magnified to show the ions that the conducting wire is comprised of and the free electrons that move between these ions. The conducting wires are both made of the same substance.

Which of the following statements correctly states how the resistivities of the sections of conducting wire in diagram (a) and diagram (b) compare to each other?

Which of the following statements correctly states how the cross-sectional areas of the conducting wires compare to each other?

Which of the following statements correctly states how the average time taken for a free electron to cross from one side of the section to the other side in diagram (a) compares to the average time taken for a free electron to cross from one side of the section to the other side in diagram (b)?

Which of the following statements correctly states how the resistance of the section of conducting wire in diagram (a) compares to the resistance of the section of conducting wire in diagram (b)?

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