If rod is initially compressed by `Deltal` length then what is the strain on the rod when the temperature
(a) is increased by `Delta theta` (b) is decreased by `Delta theta`

Explanation

To solve the problem, we need to determine the strain on a rod that is initially compressed by a length \( \Delta l \) when the temperature is changed. We will analyze two cases: when the temperature is increased by \( \Delta \theta \) and when it is decreased by \( \Delta \theta \).

### Step-by-Step Solution

1. **Understanding Strain**:
Strain (\( \epsilon \)) is defined as the change in length (\( \Delta L \)) divided by the original length (\( L \)):
\[
\epsilon = \frac{\Delta L}{L}
...