The strips of iron and zinc are riveted together to from a bimetallic strip which bends when heated . The iron is on the inside of the bend because

Options

A. it has a higher coefficient of linear expansion .
B. it has a lower coefficient of linear expansion .
C. it has a higher specific heat .
D. it has a lower specific heat .

Answer

To solve the question regarding why the iron is on the inside of the bend in a bimetallic strip made of iron and zinc, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Bimetallic Strips**: A bimetallic strip consists of two different metals (in this case, iron and zinc) that are joined together. When heated, these metals expand at different rates due to their distinct coefficients of linear expansion.

2. **Behavior of Metals upon Heating**: When the bimetallic strip is heated, both metals will expand, but they will not expand equally. The metal with a higher coefficient of linear expansion will expand more than the metal with a lower coefficient.

3. **Identifying Coefficients of Linear Expansion**: The coefficient of linear expansion (α) is a measure of how much a material expands per degree of temperature change. For this problem, we need to compare the coefficients of iron and zinc.

4. **Comparison of Iron and Zinc**: It is known that zinc has a higher coefficient of linear expansion than iron. This means that when both metals are heated, zinc will expand more than iron.

5. **Bending of the Strip**: When the bimetallic strip is heated, the zinc (which expands more) will try to elongate more than the iron. Since the iron is on the inside of the bend, it will not be able to elongate as much as the zinc on the outside, causing the strip to bend with iron on the inside and zinc on the outside.

6. **Conclusion**: Therefore, the reason why iron is on the inside of the bend in the bimetallic strip is that iron has a lower coefficient of linear expansion compared to zinc. This difference in expansion rates causes the strip to bend, with the less expanding metal (iron) on the inside of the bend.

### Final Answer:
Iron is on the inside of the bend because it has a lower coefficient of linear expansion than zinc, which causes it to expand less when heated, resulting in the bending of the strip.