8 Advanced Mistakes Students Make in Physics Board Exams (With Examples & Solutions)
Physics is considered one of the most rewarding and high-scoring science subjects, yet many students lose marks—not because they lack knowledge, but because they repeat critical mistakes during board exams. These mistakes are often overlooked, but they create major deductions in numerical questions, diagrams, and theory portions. To help students improve performance and avoid unnecessary errors, this guide explains the 8 most advanced mistakes, along with clear examples and step-by-step solutions. Students at Global NextGen Academia, where the best online teachers deliver concept-based learning, follow this pattern to consistently improve their board marks.
1. Using the Wrong Formula for the Wrong Situation
One of the most common issues is selecting a formula without understanding the condition behind it. Many formulas in physics are applicable only when certain terms—such as acceleration, rest, constant motion, or uniform motion—exist.
Example
A car moves with constant speed. Find the distance it covers in 5 seconds.
Student’s mistake
They apply:
s = ut + 1/2 at²
Where is the mistake?
This formula is for accelerated motion. The question clearly says constant speed, which means acceleration = 0.
Correct Solution
Use s = vt.
If v = 20 m/s → s = 100 m.
Explanation
Students often memorise formulas without understanding the conditions. At Global NextGen Academia, teachers emphasise concept-based learning so students know why a formula works, not just how to use it.
2. Ignoring Vector Directions
Physics is not only about numbers. Quantities like force, velocity, acceleration, displacement, and momentum are vectors, meaning they include both magnitude and direction.
Example
Force 1 = 5 N right
Force 2 = 3 N left
Student’s Mistake
5 + 3 = 8 N.
Where is the mistake?
Directions are opposite; vectors in opposite directions must be subtracted.
Correct Solution
5 N – 3 N = 2 N right
Explanation
• Students often lose marks in momentum, force diagrams, and projectile motion because they ignore directions.
• The best online physics mentors at Global NextGen Academia teach vector rules using stepwise diagram interpretations.
3. Wrong Significant Figures
Significant figures maintain precision in scientific measurement. Examiners deduct marks when students round incorrectly or give fewer digits than required.
Example
Measured value = 2.50 m
Student’s Mistake
Writing: 2.5 m
Where is the mistake?
The measurement originally had three significant figures; reducing to two loses precision.
Correct Solution
Final answer = 2.50 m
Explanation
Board exam pressure makes students write quick answers. Training at Global NextGen Academia ensures students learn SF rules through repeated practice worksheets.
4. Not Converting Units Before Calculation
Physics universally uses SI units, and examiners expect all calculations in standard form. A large number of students lose marks by inserting values directly.
Example
Speed = 72 km/h → convert to m/s.
Student’s Mistake
Using 72 directly in equations.
Where is the mistake?
72 km/h is not equal to 72 m/s.
Correct Solution
72 × 5/18 = 20 m/s
Explanation
• Many heat, electricity, and mechanical numericals require unit conversion.
• Online physics teachers at Global NextGen Academia teach students a quick SI-conversion shortcut table for speed, mass, energy, and pressure.
5. Confusing Mass With Weight
A very common conceptual mistake is mixing up mass (kg) and weight (N). Weight changes depending on gravity, while mass stays the same.
Example
Mass = 50 kg
Student’s Mistake
Weight = 50 N
Where is the mistake?
Wrong formula. Weight ≠ mass.
Correct Solution
W = mg = 50 × 9.8 = 490 N
Explanation
A simple method taught at Global NextGen Academia:
Mass stays the same everywhere — Weight changes with gravity.
6. Incorrect Ray Diagram Construction
Ray diagrams are scoring—but only when drawn with correct rules and straight geometry. Students often lose marks because of wrong rays, incorrect focal points, or incomplete labelling.
Example
(Convex Lens) Mistake
The ray through focus is drawn incorrectly.
Where is the mistake?
Students confuse ray rules.
Correct Ray Rules
• A ray through the focus → emerges parallel
• A ray parallel → passes through the focus
• A ray through the centre of the lens → goes straight
Explanation
Examiners give marks for:
• Correct rays
• Proper arrows
• Neat diagram
• Mention of F and 2F
At Global NextGen Academia, teachers train students using digital ray-diagram tools that improve accuracy.
7. Wrong Substitution or Misplacing Values
Sometimes students know the formula but place values incorrectly or flip the numerator/denominator.
Example
P = VI
Given: V = 12 V, I = 2 A
Student’s Mistake
Writes: P = V/I
Where is the mistake?
Incorrect formula substitution.
Correct Solution
P = VI = 24 W
Explanation
Always write the formula first, then substitute.
At Global NextGen Academia, solving steps are emphasised to secure method marks.
8. Writing Only Final Answer Without Steps
Board examiners award marks for each step. Students who write only the final answer lose most of the credit.
Example
Find acceleration using v = u + at.
Given: v = 20, u = 10, t = 5.
Student’s Mistake
Writes only: a = 2
Correct Solution (Full Marks Method)
20 = 10 + 5a
20 – 10 = 5a
a = 2 m/s²
Explanation
Always show formulas, substitution, and solving steps—even if the question looks simple.
Summary
Physics is not difficult; it requires careful reading, concept clarity, correct formulas, vector understanding, unit conversion, precise diagrams, and proper stepwise solutions. Students at Global NextGen Academia avoid these 8 advanced mistakes through systematic practice, real-life examples, and concept-based online learning from highly experienced teachers. By correcting these errors, students can improve their board exam scores by 20–25 marks with confidence.