Final answer:
Total internal reflection in a right-angled isosceles glass prism can occur when light enters perpendicular to one leg and reflects off the hypotenuse, or when light enters through the hypotenuse and reflects off one of the legs, as long as the incident angle is greater than the critical angle.
Step-by-step explanation:
Two situations of total internal reflection in a right-angled isosceles glass prism involve light entering the prism from one of the legs and reflecting off the hypotenuse at an angle greater than the prism's critical angle. First, consider a light ray entering perpendicular to one leg of the prism and reflecting off the hypotenuse inside the prism. Since the angle of incidence at the hypotenuse is 45°, and the critical angle for glass-air boundary is typically less than this, total internal reflection will occur.
Another situation is when light enters through the hypotenuse at an angle and encounters one of the legs at an angle greater than the critical angle. This will also result in total internal reflection because light tries to exit the prism but the incident angle exceeds the critical angle, thus reflecting back into the prism.
In both cases, no light escapes through the hypotenuse, and all of it is reflected back into the glass, demonstrating the principle of total internal reflection.