KCET 2025 Physics Paper

When light passes into a non-reflecting, non-absorbing medium, no energy is lost at the boundary. In particular:
Energy flux is given by the (time-averaged) Poynting vector

→

S

=

→

E

×

→

H

For no reflection and no absorption, the tangential components of both fields are continuous across the interface:
E1=E2,‌‌H1=H2.
Hence the incident and transmitted fluxes are equal:
S1=E1H1=E2H2=S2
Since all the energy that arrives is carried forward, the total energy carried by the wave remains the same.
Answer: Option A (remains same).