Rahul DubeyDropperSample· 3d ago
Fridge door open makes the room hotter, COP of 9 seems odd, and fridge cooling lowers entropy. Does it break the second law?
A third-attempt student asking a first-principles question late at night.
⚛️ NEET Physics
Doubts and answers on every NEET Physics chapter, by students.
Browse chapters in NEET Physics
- #emi 3
- #gravitation 3
- #kinematics 3
- #kinetic-theory 3
- #ray-optics 3
- #semiconductors 3
- #waves 3
- #atoms 2
- #circular-motion 2
- #current-electricity 2
- #de-broglie 2
- #em-waves 2
- #newtons-laws 2
- #nuclei 2
- #oscillations 2
- #photoelectric-effect 2
- #rotational-motion 2
- #thermodynamics 2
- #ac-generator 1
- #alpha-scattering 1
- #alternating-current 1
- #banking 1
- #bar-magnet 1
- #basics 1
- #beams 1
- #capacitors 1
- #capillarity 1
- #centre-of-mass 1
- #choke-coil 1
- #collisions 1
- #conductors 1
- #davisson-germer 1
- #derivations 1
- #dipole 1
- #displacement-current 1
- #doppler-effect 1
- #drift-velocity 1
- #elastic-behaviour 1
- #elasticity 1
- #electric-charge 1
- #electric-potential 1
- #em-spectrum 1
- #energy-bands 1
- #energy-loss 1
- #entropy 1
- #error-analysis 1
- #faraday-law 1
- #fission-fusion 1
- #fluids 1
- #frame-of-reference 1
- #friction 1
- #galvanometer 1
- #gauss-law 1
- #helical-path 1
- #huygens-principle 1
- #hysteresis 1
- #ideal-gas 1
- #inertia 1
- #internal-resistance 1
- #keplers-laws 1
- #kirchhoff 1
- #lenz-law 1
- #logic-gates 1
- #lorentz-force 1
- #magnetic-dipole 1
- #magnetic-materials 1
- #malus-law 1
- #mean-free-path 1
- #mirror-formula 1
- #modern-physics 1
- #moment-of-inertia 1
- #momentum 1
- #newton-cooling 1
- #nuclear-density 1
- #parallax 1
- #parallax-lab 1
- #pascals-law 1
- #polarisation 1
- #potentiometer 1
- #practical 1
- Commons CommunityTeam· 3d ago
My maths is weak. What is the minimum maths I actually need to survive NEET Physics?
Physics feels impossible when algebra and trigonometry feel shaky. Here is a realistic list of what you need, what you can skip, and how to build it alongside the chapters.
- Yash Tiwari11thSample· 5d ago
In an inelastic collision kinetic energy is lost, so how can momentum still be conserved?
Aaj phir ek basic doubt aaya hai bhai. Work Energy and Power, collisions part. NCERT says in all collisions the total linear momentum is conserved, but kinetic energy is conserved only in elastic collisions. Mujhe ye sam
- Yash Tiwari11thSample· 6d ago
Geostationary satellite height fixed kyun hai, only over equator, and are astronauts really at zero gravity?
bhai Gravitation ka last part, satellites. NCERT says a geostationary satellite stays about 36,000 km above the Earth's surface, period 24 hours, orbit in the equatorial plane, and moves west to east. Mujhe 3 cheezein sa
- Siddharth RaoDropperSample· 8d ago
Rolling down an incline: why does friction not reduce the energy, and which shape reaches first?
I'm repeating, and rotational motion is the chapter I have always handled with formulas, not understanding. This time I want the concept. Pure rolling means v=\omega R for the centre. Total KE =\tfrac12mv^2+\tfrac12I\ome
- Riya Singh12thSample· 9d ago
Magnetic force does no work, yet the velocity direction changes. And what's the pitch of the helical path?
Chapter: Moving Charges and Magnetism. I'm trying to see the story in the equations, but a few lines feel like they contradict each other. The force on a charge is \vec F = q \vec v\times\vec B . It's always perpendicula
- Commons CommunityTeam· 9d ago
How much time is Semiconductors and Logic Gates actually worth? Can I just skim it?
The last Physics unit is mostly facts, circuits and truth tables. How much time does it deserve, and when in the year should you do it?
- Diya Menon11thSample· 10d ago
Reading a progressive wave equation: how do I find direction, speed, wavelength, and what is particle speed?
ahh my teacher gave this equation and I just stared at it
- Tanvi Deshmukh12thSample· 10d ago
Flux = BA cosθ, but which angle is θ? And why is emf zero when flux is maximum?
ok so I made a really neat table in my notes for Faraday's law but the very first line is breaking my brain. NCERT defines flux as \Phi B = \mathbf{B}\cdot\mathbf{A} = BA\cos\theta . In the example I solved, a coil is pl
- Sara Fernandes11thSample· 10d ago
Two trains crossing each other: when do I add speeds and when do I subtract? And the v_AB sign thing
Football practice got cancelled so I decided to be productive and do relative velocity. It did not go well. Here's the problem. Train A is 100 m long, train B is 150 m long, on parallel tracks. a They move in opposite di
- Harsh Gupta12thSample· 12d ago
Photoelectric effect: why does stopping potential ignore intensity while saturation current doesn't? My brain says brighter = faster electrons
Photoelectric effect, and my brain says: brighter light = more energy = faster electrons. But NCERT says the stopping potential depends on the frequency, not on intensity, while the photocurrent depends on intensity. Why
- Aarav Kulkarni11thSample· 12d ago
Mean free path: where does the √2 come from, and how does it change with temperature?
I made a small list of cases but I think two of them are wrong.
