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## Class 10 Physics (India)

### Course: Class 10 Physics (India)>Unit 3

Lesson 3: Circuits, Ohm's law & resistance

# Ohm's law graph (verifying Ohm's law)

Let's learn how to graphically verify Ohm's law in practice. We will also learn about Ohmic and non-Ohmic devices. Created by Mahesh Shenoy.

## Want to join the conversation?

• Ideally voltage should be determining the current, so in the graph voltage should be plotted along the x-axis while the current should be on the y-axis. Why it is plotted the other way round?
• It's done so because to find resistance according to Ohm's law, we are dividing the voltage by current. So when we find the slope, which is
``(Δy/Δx)``
of the straight-line graph (i.e., resistance), we need the voltage to be on the Y-axis (numerator of the fraction) and current on the X-axis (denominator). Hence, the other way round.
• how can a substance just 'not obey Ohm's Law'?
• When the resistance changes and the relationship between current and voltage is not directly proportional. Resistance will be still the rate V/I for every pair I-V but it does not stay the same
(1 vote)
• Why does the current have to be the same in a series current to find the relationship between the voltage and resistance
• why do semiconductors like LED bulbs not obey ohm's law?
• isn't voltage the independent variable? shouldn't it be on the x axis?
(1 vote)
• Strictly speaking, one should really put the voltage on the x-axis as it is the independent variable, but the calculation is simpler if the voltage is on the y-axis.
• For the second example where you say it doesn't obey ohm's law, could you say it does to an extent since it does pass through the origin at the beginning?
(1 vote)
• is I can equal to V any how
(1 vote)
• why exactly the line should be straight in the graph?
(1 vote)
• The line formed in the graph is diagonal(straight) because:
the line represents the potential difference(p.d) and the current(I) at each time period.As p.d is directly proportional to I.Thus the line in the graph is a diagonal(straight).
(1 vote)