The Three Mistakes Costing You Marks on Physics Numericals

When students lose marks on Physics numericals, it's almost never because they didn't understand the concept — it's execution errors that a rushed exam-day mind lets slip through.

The first common mistake is unit inconsistency — mixing CGS and SI values mid-calculation. Build the habit of converting everything to SI units in the first line of your working, before any calculation begins.

The second is sign convention errors, especially in optics and electrostatics, where a flipped sign silently produces a plausible but wrong answer. Always state your sign convention explicitly before substituting values.

The third is rounding too early. Carry full precision through intermediate steps and round only the final answer — early rounding compounds error across multi-step numericals.

Build a habit of a 10-second sanity check on every numerical answer: does the order of magnitude make physical sense? A calculated human walking speed of 400 m/s should immediately signal an error.