The resistance of an object acting as a resistor is directly proportional to its:resistivity.cross-sectional area.length.

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11ecba2d_1307_4250_a3bf_65b4c9686de0_MD0008_00 In electronics, resistance (R) refers to the capacity of an object acting as a resistor to oppose the movement of charge (ie, current). Resistance is expressed by Ohm's law as the ratio of the voltage (V) applied across the resistor relative to the current (I) flowing through it. The resistance of a given object (eg, a wire within a circuit) quantifies the relative difficulty by which charge moves from one end of the object to the other. As a result, resistance increases in direct proportion to length (L) because increased length forces charge to travel through a greater distance of resistant material (Number III): 11ecba2d_1307_4251_a3bf_27e0afd7152f_MD0008_00 Conversely, resistance decreases as the cross-sectional area (A) increases because additional cross-sectional area provides more parallel channels through which electrical charge can flow. As a result, resistance is inversely proportional to cross-sectional area (Number II): 11ecba2d_1307_6962_a3bf_e9719fbe5e41_MD0008_00 As another variable that influences resistance, resistivity (ρ) can be used to quantify the differential resistance of materials. Most often reported in ohm-meters (Ω-m), resistivity is the inherent resistance per unit length for a uniform cross-section of the object and is expressed mathematically as: 11ecba2d_1307_6963_a3bf_d9b2ea4469b4_MD0008_00 The resistance of two objects with equal physical dimensions can differ based on the material that constitutes the resistors. Accordingly, the resistance of an object made from a high-resistivity material will be greater than the resistance of an object made from a low-resistivity material of equal physical dimensions. Therefore, resistivity is directly proportional to resistance (Number I). Consequently, the equation for resistivity can be rearranged to yield an overall expression for resistance: 11ecba2d_1307_6964_a3bf_23a1dd5e2a28_MD0008_00 Educational objective: The resistance of an object is directly proportional to its resistivity and length but inversely proportional to its cross-sectional area. Resistivity assesses the intrinsic resistance within a defined volume of a material.

The Resistance of an Object Acting as a Resistor Is