11.3.A—Describe the resistance of an object using physical properties of that object

Describe the resistance of an object using physical properties of that object.

• Resistance is a measure of the degree to which an object opposes the movement of electric charge.
• The resistance of a resistor with uniform geometry is proportional to its resistivity and length and is inversely proportional to its cross-sectional area. Relevant equation:
  • i. Resistivity is a fundamental property of a material that depends on its atomic and molecular structure and quantifies how strongly the material opposes the motion of electric charge.
  • ii. The resistivity of a conductor typically increases with temperature.
  • iii. The total resistance of a resistor with uniform geometry, but that is made of a material whose resistivity varies along the length of the resistor, is given by