Physics · Class 11
7 free physics experiments and lesson notes for Units & Measurements, with model limits, worked examples and Tamil explanations.
A physical quantity combines a number and a unit. SI has seven base units: metre, kilogram, second, ampere, kelvin, mole and candela. Derived units combine them: a newton is kg m s⁻². A named derived unit is not an eighth base unit. A unit system chooses its standards: SI mechanics uses metre, kilogram and second; CGS uses centimetre, gram and second. Measurement lets us compare a quantity with a shared standard.
Run this experiment →Changing a unit changes the numerical value, not the physical quantity. Convert through the common base unit. Area scales with the square of a length factor; volume scales with its cube. This laboratory includes exact prefix and time conversion factors, not temperature offsets.
Run this experiment →A ruler can only distinguish its marked divisions. Its least count is the smallest interval it can read. A finer scale reduces rounding uncertainty, but does not automatically remove calibration or reading errors.
Run this experiment →Leading zeros locate the decimal point; they are not significant. Zeros between significant digits count, as do trailing zeros explicitly written after a decimal point. An integer such as 1200 is ambiguous without a precision statement; scientific notation removes that ambiguity.
Run this experiment →Separate the best estimate from its uncertainty. For sums and differences, absolute worst-case bounds add. Products, quotients and powers often use first-order relative error rules when errors are small. This lab also calculates exact intervals so the approximation is visible.
Run this experiment →Every physical equation must have matching dimensions on both sides. Force has dimensions M L T⁻². Multiplying mass by acceleration produces the same dimensions; multiplying mass by velocity does not. Dimensions describe the quantity type and do not depend on the selected unit.
Run this experiment →Assume a pendulum period depends only on length l and gravity g through T = C lᵃ gᵇ. Matching time dimensions gives a = 1/2 and b = −1/2. It cannot determine C. The ideal small-angle pendulum has C = 2π; that result comes from its dynamics.
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