Duduli

During a phase change, the heat supplied to a substance is used to overcome intermolecular forces and change its molecular arrangement, rather than increasing its temperature. This energy is called latent heat. For example, while ice melts at 0°C, its temperature remains 0°C until all the ice has melted.  So, even though temperature remains constant, internal energy changes.

Entropy(S) is a thermodynamic state function that measures the degree of energy dispersal or randomness/disorder of a system. Unit:- J K-¹ For Specific entropy  Unit :- J Kg K-¹   ●                         dS=dQ/T For reversible process ds=0 For irreversible process ds>0 Examples :- ●Ice melting → entropy increases. ●Water evaporating → entropy increases. ●Gas expanding freely → entropy increases. ●Heat naturally flowing from hot to cold → total entropy increases.

Electromagnetic induction is the phenomenon of production of an induced emf (electromotive force) in a closed circuit whenever the magnetic flux linked with the circuit changes. The induced emf is given by e=-dΦ/dt For a coil of N-turns e=-NdΦ/dt where magnetic flux is Φ=BAcosθ Lenz's law:- The induced current always flows in such a direction that it opposes the change in magnetic flux that produces it.

Resonance is the phenomenon in which a system oscillates with maximum amplitude when the frequency of the external periodic force equals its natural frequency.

A wave function (ψ) is a mathematical function that describes the quantum state of a particle. Its squared magnitude gives the probability density of finding the particle at a particular position. |ψ|² = Probability density In short : The wave function tells us what we can know about a quantum particle and where it is likely to be found.

Quantum tunneling is a phenomenon where a quantum particle can pass through a potential barrier even when its energy is less than the barrier height. In classical physics: ❌ Impossible In quantum physics: ✅ Possible Example : It is responsible for α-decay and is used in scanning tunneling microscopes (STM).

The Doppler effect is the apparent change in frequency of a wave when there is relative motion between the source and the observer. ●Source approaching → frequency increases → higher pitch ●Source moving away → frequency decreases → lower pitch Example :-The pitch of an ambulance siren sounds higher as it approaches you and lower as it moves away.

Chemical potential is the change in the Gibbs free energy of a system when one mole of a substance is added at constant temperature and pressure.                     μ=(∂G/∂n)ₜ,ₚ where G is Gibbs free energy and n is the number of moles. ● Chemical potential represents the driving.     force for the movement of particles. ☆  Particles naturally move from higher.             chemical potential to lower  chemical potential. ☆  At equilibrium, the chemical potential is.       the  same throughout the system.

Even though billions of stars emit light, space appears dark because most of the universe is empty.Light travels in straight lines and doesn’t illuminate empty space unless it interacts with matter. So, between stars and galaxies, there is very little material to scatter the light toward our eyes.