Resistivity and Resistance Formula, Conductivity, Temperature Coefficient, Physics Problems

This physics video tutorial explains the concept of resistivity and resistance of electrical conductors like copper and silver as well as semiconductors such as silicon, germanium, and carbon graphite. It provides the formula to calculate the resistance of a metal or wire using resistivity. It discusses the inverse relationship between resistivity and conductivity as well the direct relationship between resistance and temperature. Electrical conductors such as metals have a positive temperature coefficient of resistivity which means that as the temperature of a metal increases, the resistivity will increase and the conductivity will decrease. For metalloids or semiconductors, the opposite is true. These elements have a negative temperature coefficient which means that the resistance will decrease as the temperature increases which correlates to an increase in conductivity. The resistivity depends on the length of the wire as well as the cross sectional area. Long wires have more resistance and short wires conduct electricity better. Thick wires have less resistance than thin wires. This video shows you how to calculate the temperature by simply measuring the current in a metal using a known voltage which has practical applications in digital thermometers.

Electric Current In Circuits:

The Electric Battery:

Ohm's Law Problems:

Resistor Color Code:

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Internal Resistance of a Battery:

Electromotive Force of a Battery:

Drift Velocity and Current Density:

Potential Difference Between Two Points:

Alternating Current Vs Direct Current:

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Schematic Diagrams & Symbols:

Open, Closed, and Short Circuits:

Resistors In Series:

Resistors In Parallel:

Physics PDF Worksheets:

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[dwendzzeldrian]

Air conditioning units are mostly used during summer period. A simple electrical circuit may represent the set-up of the aircon: a rheostat connected in series with the whole cooling mechanism (represented by a single resistor) and these combination is then connected in series with the power switch. The whole circuit is supplied by a 220 V power supply. The following are the values of the components: rheostat (10 ohms to 10, 000 ohms) and the cooling mechanism (100 ohms). By theory, the higher the power consumption of the cooling unit, the higher the current flowing in the cooling mechanism. Given the following scenarios, answer the following:
b) Let us assume that the current value of the rheostat is 1000 ohms. Assuming that the value of the total current represents the current temperature (2 A for 18 degrees and 0.2 A for 25 degrees). Draw the electrical diagram and calculate the temperature at 1000 ohms.

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