Heating Effect and Resistance

<aside> ❗ Electricity prefers the path of least resistance.

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Data booklet:

$$ \text{Kirchoff's Circuit Laws:}\\ \Sigma V = 0\space(loop)\\\Sigma I= \space0 (junction) $$

Ohm’s Law:

$$ V\propto I\\ V=IR $$

Conservation of Energy:

$$ Work\space{}Done = qV $$

Potential Difference:

Potential difference is the difference in the amount of energy that charge carriers have between two points in a circuit.

Electric Resistance

The electric resistance R of a conductor is defined as the potential difference V across it ends divided by the current I passing through it:

Resistors:

Ohmic Materials

Materials that obey Ohm’s law have a constant resistance at constant temperature. Such materials are qualified as ohmic material.

Gradient is constant, material is Ohmic

Gradient is not constant, material is non-Ohmic

$$ \text{To find resistance (R), take 2 points on the gradient (preferably 0,0 and maximum)}\\R = \frac{1}{gradient} \\R = \frac{1}{-1.6*10^{-3}/-1.2} $$

• How to explain that a lamp filament is non ohmic?

<aside> ⚠️ Three factors affect the resistance at constant temperature: - The nature of the material : resistivity

• The length of the wire : L (m)
• The cross-sectional area of the wire, A (m^2)

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Thus, we have: