In total internal reflection (TIR), all incident light energy is reflected back into the original medium, resulting in no energy loss, unlike in refraction where some energy is transmitted and some is reflected. This phenomenon occurs because Snell's Law dictates that the sine of the angle cannot exceed 1, preventing refraction at steep angles. When light transitions between different media, it changes direction, and at acute angles, it reflects entirely instead of refracting. This principle explains visual effects like the twinkling of water and the sparkling of bubbles, which occur during TIR. Overall, TIR demonstrates that energy is conserved as it reflects rather than refracts.