# Kirchhoff's loop rule problem

## Homework Statement

$$-L\frac{dI}{dt}+IR = 0$$

or

$$L\frac{dI}{dt}+IR = 0$$

## The Attempt at a Solution

#### Attachments

• griffiths2point29.jpg
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Well what they do in the second link is use the given fact that the current is increasing to decide what the sign must be. But the same equation should hold whether the current is increasing or decreasing. How do you decide which of my equations to use without knowing whether the current is increasing or decreasing through the inductor?

BTW, the do we know the current is decreasing here? Why?

I don't mean to be rude, but can you help me with this specific example?

Last edited:
malawi_glenn
Homework Helper

say we go clockwise around the smaller loop starting from S and record the voltage changes as we go around. How do we get the sign of the first voltage change?

Astronuc
Staff Emeritus