V-IR Equation & I-V Graphs

Question 1

Most important equation in electricity topic

Answer 1

V = IR

Question 2

What are the relations between the symbols shown in V = IR

Answer 2

Hypothetically, if R were to stay constant, when we increase V, I would increase proportionatally

Question 3

How does the line on a V-I graph look if I is increasing but resistance stays the same. How can this line vary? Why might we not get results that look like this in practice?

Answer 3

Straight line in upwards direction as V is directly proportional to I if R were to stay constant.

The line’s steepness can vary depending on the size of the resistance

In practice, we might not get results like this because the wires can heat up if they have been left on for a while and when temperature increases, so does resistance. In theory, we are just assuming temperature stays constant.

Question 4

How does the line of a filament lamp look like on a V-I graph?

Answer 4

As current flows through the tiny filament, the line curves up to the origin, but as the filament heats up, the resistance goes up and therefore the line gets less steep