Resistance

Question 1

recall

• Recall the formula for Ohm’s law.

Answer 1

Using the symbols V for voltage, R for resistance and I for current the formula for Ohm’s Law is: V = R × I.

Question 2

calculate

• Calculate voltage, current or resistance using Ohm’s law.

your car battery is 12v Dc source. typically you would use a fuse that can handle a 5A surge. what is the resistance

Answer 2

R = v/I
R = 12/5
R = 2.4 ohms

Question 3

explain

• Explain what causes resistance.

Answer 3

Resistance occurs because moving electrons in current bump into atoms of matter. Resistance reduces the amount of electrical energy that is transferred through matter.

Question 4

describe

• Describe factors that affect resistance.

Answer 4

Factors Affecting Resistance include material, length, cross-sectional area, and temperature. The type of material determines its resistivity, while longer conductors cause more resistance.

Question 5

sketch

• Sketch graphs for ohmic and non-ohmic components.

Answer 5

A resistor is ‘Ohmic’ if as voltage across the resistor is increased, a graph of voltage versus current shows a straight line (indicating a constant resistance). The slope of the line is the value of the resistance. A resistor is ‘non-Ohmic’ if the graph of voltage versus current is not a straight line.