Matching Physical Devices with Operational Principles and Processes

Step-by-step Matching:

1. Bimetallic strip (A):

• Consists of two different metal strips with different linear thermal expansion coefficients $\alpha_1 \neq \alpha_2$ riveted together. Upon temperature change, unequal expansion causes bending. Hence, it directly utilizes thermal expansion of solids ($s$) and involves energy conversion of heat into mechanical deformation ($q$).
• Matching: $(\text{A}) \rightarrow (\text{q}, \text{s})$ [or ($s$) alone].

1. Steam engine (B):

• Operates as a thermodynamic heat engine converting thermal energy of steam into mechanical work. Hence, it functions on energy conversion ($q$).
• Matching: $(\text{B}) \rightarrow (\text{q})$.

1. Incandescent lamp (C):

• Electrical current heats the tungsten filament to incandescent temperatures (~$2500\text{ K}$), emitting visible light via thermal radiation from a hot body ($p$). It also converts electrical energy into heat and light (energy conversion, $q$).
• Matching: $(\text{C}) \rightarrow (\text{p}, \text{q})$ [or ($p$) alone].

1. Electric fuse (D):

• High fault current causes excessive Joule heating ($I^2 R t$), which leads to the melting ($r$) of the low melting-point alloy wire, thereby opening the circuit. It also represents energy conversion ($q$) of electrical energy to thermal energy.
• Matching: $(\text{D}) \rightarrow (\text{q}, \text{r})$ [or ($r$) alone].

Matching:
$(\text{A}) \rightarrow (\text{q}, \text{s}),\; (\text{B}) \rightarrow (\text{q}),\; (\text{C}) \rightarrow (\text{p}, \text{q}),\; (\text{D}) \rightarrow (\text{q}, \text{r})$

Correct Answer: A