Answer

1. What is Strain Gauge?

Resistive sensor measuring strain $\epsilon = \Delta L/L$ via resistance change. Bonded to structure, deforms with it.

2. How It Works

Resistance $R=\rho L/A$. Strained → $L$ ↑, $A$ ↓ → $R$ changes: $\Delta R/R = G_F \cdot \epsilon$, $G_F$ gauge factor (~2). Wheatstone bridge measures $\Delta R$: $V_o = V_s \cdot (\Delta R/4R)$ for quarter bridge.

3. Advantages

• High sensitivity for force/pressure/weight.
• Small, cheap, static + dynamic.
• Easy bridge interfacing.

4. Disadvantages

• Temperature drift (needs compensation).
• Small signal (mV) needs amplification.
• Bonding sensitive, hysteresis.
• Nonlinear for large strain.

5. Applications

• Load cells, weighing scales.
• Robot force sensing, torque measurement.
• Structural health monitoring.
• Pressure diaphragms.

Final Answer

Strain gauge = $\Delta R/R=G_F\epsilon$ via Wheatstone bridge; advantages high sensitivity for force, used in load cells/robot force, disadvantages temperature drift and small signal.