Physics: Mechanics, Electricity, Optics and Modern Physics
The BVP CET physics section tests Class XI–XII level concepts across mechanics (projectile motion, Newton's laws, work–energy, rotational dynamics), properties of matter, thermodynamics and kinetic theory, simple harmonic motion and waves, electrostatics and capacitors, current electricity, magnetic effects, ray optics, and modern physics (photoelectric effect, Bohr model, radioactivity). Marks go to candidates who move fluently between a physical situation, its governing equation and a numerical answer.
Formula discipline
Kinematics equations hold only at constant acceleration. Work–energy is a scalar route that bypasses time; momentum conservation is a vector route that bypasses force. In rotation, translate every linear quantity: F→τ, m→I, p→L.
Worked example
A ball is thrown at 20 m/s at 30° above the horizontal from level ground. Take g = 10 m/s². Vertical component u_y = 20 sin30° = 10 m/s; horizontal u_x = 20 cos30° = 17.32 m/s. Maximum height H = u_y²/(2g) = 100/20 = 5 m. Time of flight T = 2u_y/g = 2 s. Range R = u_x·T = 17.32 × 2 = 34.6 m, matching u²sin2θ/g = 400 × 0.866/10. Keep one value of g throughout; mixing 9.8 and 10 corrupts the third significant figure.
Traps
- Applying v² = u² + 2as across a reversal of acceleration direction.
- Forgetting that in an isolated capacitor the charge, not the voltage, is fixed.
- Sign of work in thermodynamics: work done by a gas is positive in ΔU = Q − W.
- Choosing a sign convention in optics and then abandoning it mid-problem.
- Treating rms and peak values of AC as interchangeable.