NEET doubts
700 doubts found
What does “No isolated magnetic poles” actually mean in Magnetism & Matter, and why does it matter for NEET?
Cutting a bar magnet produces smaller north-south dipoles, not separate monopoles. Therefore net magnetic flux through any closed surface is zero.
What does “Bohr's quantised orbits” actually mean in Atoms, and why does it matter for NEET?
Bohr allowed only orbits with angular momentum n h/(2pi). An electron in a stationary orbit does not radiate; light is emitted or absorbed only during a transition.
What does “Mass defect and binding energy” actually mean in Nuclei, and why does it matter for NEET?
A bound nucleus has less mass than its separated nucleons. The missing mass corresponds to the energy released during binding: B = Delta m c^2.
What does “Accuracy, precision and uncertainty” actually mean in Experimental Skills, and why does it matter for NEET?
Accuracy means closeness to the accepted value; precision means repeatability. Repeated measurements can reduce random uncertainty but cannot remove a systematic calibration error.
I keep getting “Superposition” questions wrong in Waves & Sound. What's the trap?
adding intensities directly before considering phase.
I keep getting “Circular and helical motion” questions wrong in Moving Charges & Magnetism. What's the trap?
using the total speed to find the circular radius when motion is helical.
I keep getting “Hooke's law and elastic limit” questions wrong in Mechanical Properties of Solids. What's the trap?
using Hooke's law up to fracture.
I keep getting “Transverse nature” questions wrong in Electromagnetic Waves. What's the trap?
drawing E or B along the direction of travel.
What does “Errors in measurement” actually mean in Units, Dimensions & Measurement, and why does it matter for NEET?
absolute error = |measured − true|, relative error = absolute/true, percentage error = relative × 100.
What does “Equations of motion” actually mean in Kinematics, and why does it matter for NEET?
the v=u+at family that connects u, v, a, s and t — valid only for constant acceleration.
What does “Newton's third law” actually mean in Laws of Motion, and why does it matter for NEET?
every action has an equal and opposite reaction, and the two forces act on different bodies.
What does “Conservation of mechanical energy” actually mean in Work, Energy & Power, and why does it matter for NEET?
when only conservative forces act, KE + PE stays constant.
What does “Moment of inertia” actually mean in Rotational Motion, and why does it matter for NEET?
the rotational analogue of mass; it depends on both the mass and how it is distributed about the axis.
What does “Gravitational potential energy” actually mean in Gravitation, and why does it matter for NEET?
for large distances PE = −GMm/r (negative, zero at infinity), not mgh.
What does “Second law of thermodynamics” actually mean in Thermodynamics & Kinetic Theory, and why does it matter for NEET?
heat flows spontaneously from hot to cold, and no engine can be 100% efficient.
What does “Wave motion” actually mean in Oscillations & Waves, and why does it matter for NEET?
a wave transfers energy and momentum through a medium without transporting the medium itself.
What does “Electric potential” actually mean in Electrostatics, and why does it matter for NEET?
the work done per unit charge to bring a charge from infinity to a point, V = kQ/r.
What does “Series and parallel resistors” actually mean in Current Electricity, and why does it matter for NEET?
in series the current is the same and resistances add; in parallel the voltage is the same and 1/R values add.
What does “Lenz's law” actually mean in Magnetism & Electromagnetic Induction, and why does it matter for NEET?
the induced current always opposes the change that produced it, ensuring energy conservation.
What does “Bohr model” actually mean in Modern Physics, and why does it matter for NEET?
electrons occupy quantised orbits; for hydrogen E_n = −13.6/n² eV.
Why does a raindrop or a skydiver stop speeding up and fall at a steady 'terminal' velocity?
As the drop speeds up, the upward viscous drag of the air (which grows with speed) and buoyancy increase until they exactly balance gravity.
Which spectacle lens fixes short-sightedness, and which fixes long-sightedness?
A short-sighted (myopic) eye focuses images in front of the retina, so it needs a concave (diverging) lens to spread the rays out before they enter the eye.
How do Polaroid sunglasses cut the glare off water and roads?
Light reflected off horizontal surfaces (water, wet roads, car bonnets) is mostly polarised horizontally.
Our mains is '230 V', but I read the peak is about 325 V — which is right?
Both.