type: glossary | topic: all-experiments-terms
| Term | Definition |
|---|---|
| Least Count (LC) | Smallest value measurable by an instrument. Vernier: 1 MSD − 1 VSD. Screw gauge: pitch/divisions. |
| Main Scale Reading (MSR) | Reading on the main scale just before (or at) the Vernier/thimble zero. |
| Zero Error | Error when instrument reads non-zero for zero measurement. Positive: Vernier zero right of main scale zero. Negative: left. |
| Backlash Error | Error in screw gauge from reversing rotation direction. Caused by slack in screw thread. |
| End Correction (e) | Distance above tube rim where antinode forms in resonance tube. e = (l_{2}−3l_{1})/2. |
| Terminal Velocity (v_t) | Constant velocity when net force = 0: weight = buoyancy + Stokes drag. |
| Wheatstone Bridge | Electrical circuit for precise resistance measurement using null condition. |
| Balance Length (l) | Length from end A where galvanometer reads zero in a metre bridge. |
| Figure of Merit (k) | k = I/θ (A/div). Current per scale division for a galvanometer. Smaller k = more sensitive. |
| Threshold Voltage (V_th) | Minimum forward voltage for significant current flow in a diode. Si: 0.7V; Ge: 0.3V. |
| Breakdown Voltage (V_Z) | Reverse voltage at which Zener diode starts conducting in reverse. Used for regulation. |
| Minimum Deviation (δ_min) | Minimum angle of deviation for a prism; occurs when i = e. Used to find μ. |
| Apparent Depth | Depth at which an object submerged in a denser medium appears to be. Apparent depth = real depth/μ. |
| Effective Length (l_eff) | For a pendulum: string length + bob radius. The distance from pivot to centre of mass of bob. |
| Stress | Force per unit area: σ = F/A. SI unit: Pa (N/). [ML^{-1}$$T^{-2}]. |
| Strain | Fractional change in length: ε = /L. Dimensionless. |
| Young's Modulus (Y) | Ratio of stress to strain in the elastic (linear) region. Y = FL/(A). SI unit: Pa. |
| Surface Tension (S) | Force per unit length (or energy per unit area) at a liquid surface. S = hrρg/(2cosθ). SI unit: N/m. |
| Viscosity (η) | Resistance of a fluid to flow. η = [2(ρ−σ)g/(9v_t)]. SI unit: Pa·s. |
| Contact Angle (θ) | Angle between the liquid surface and the solid surface at the contact line. θ=0° for water-glass; θ=140° for mercury-glass. |
| Water Equivalent (W) | Equivalent mass of water with the same heat capacity as the calorimeter. W = m_cal × c_cal / c_water. |
| Depletion Layer | Region at p-n junction depleted of mobile charge carriers. Widens in reverse bias; narrows in forward bias. |
| Saturation Current | Small constant reverse current in a p-n junction due to minority carriers. Increases with temperature. |