Friday, 27 June 2014

Build Your First Robot - Resistors in series and parallel

In the last post, we learnt the way of calculating resistance required in a circuit. In today's post, we will discuss about the different combinations in which resistors can be placed to obtain any non-standard resistor values.

Resistors in Series

As the name suggests, here the resistors are placed in series. In this type of configuration the potential differences across each resistor would be different and would be directly proportional to the value of the resistor. More the resistance, more would be the potential difference. The current through the circuit would be constant. Hence, from this observation:

Vt = V1+V2+V3+.....+Vn

Therefore, IRT = IR1+IR2+IR3+......+IRn

Hence, RT = R1+R2+R3+......+Rn

Resistors in parallel

In this type of configuration, the ends of two more resistors meet. Here the current across the ends of resistors varies depending on the value of resistance. More the resistance, less would be the current. The potential difference across the resistors is the same. Hence :
V/RT = V/R1+V/R2+V/R3+......+V/Rn
By factoring out the potential difference we get:
1/RT = 1/R1+1/R2+1/R3+......+1/Rn

By the end of this post, now we will be able to use resistors without any hesitations in our projects.
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