If the incident ray strikes at a point A making an angle of 45 degrees with the first mirror, at what height on the second mirror placed perpendicularly the light undergo a second reflection?

To answer this question, we need more information such as the distance between the two mirrors and the height at which the light strikes the first mirror. However, I can explain how to solve this problem in general terms.

1. First, we need to understand that when light strikes a mirror, the angle of incidence is equal to the angle of reflection. This means that if the light strikes the first mirror at a 45-degree angle, it will also reflect off at a 45-degree angle.

2. Next, we need to consider the geometry of the situation. If the mirrors are placed perpendicularly, then they form a right angle. When the light reflects off the first mirror at a 45-degree angle, it will travel in a direction that forms a 45-degree angle with both mirrors.

3. Now, we can use trigonometry to find the height on the second mirror where the light will strike. If we know the distance between the two mirrors (let's call this d), then the height (h) on the second mirror where the light will strike is given by h = d * tan(45 degrees).

4. Since the tangent of 45 degrees is 1, this simplifies to h = d. So, the light will strike the second mirror at a height equal to the distance between the two mirrors.

Remember, this solution assumes that the light strikes the first mirror at a point that is level with the bottom of the second mirror. If the light strikes the first mirror at a different height, then we would need to adjust our calculation accordingly.