To solve this problem, we need to analyze the path of the light ray and the angles of incidence and reflection as it bounces off the walls.

1. Initial incidence on $v$:

   • The light ray initially hits $v$ at an angle of incidence of 50 degrees.
   • By the law of reflection, the angle of reflection is also 50 degrees.

2. Incidence on $h$:

   • After reflecting off $v$, the ray will travel downwards to hit wall $h$.
   • Since $v$ is perpendicular to $h$, the ray hitting $h$ has traveled a straight path, so the angle it makes with $h$ will be the same as the angle it made with $v$ after reflection, which is 50 degrees.

3. Incidence on $s$:

   • The ray reflects off $h$ at an angle of 50 degrees, making its path travel towards wall $s$.
   • Now, let's calculate the angle of incidence on $s$:
     • Given that the angle at $B$ is 75 degrees, the angle between $h$ and $s$ is 105 degrees (since the total angle around point $B$ is 180 degrees).
     • The ray hits $s$ at an angle of 50 degrees (angle of incidence on $s$ is $105^\circ - 50^\circ$).

4. Incidence on $v$ the second time:

   • After reflecting off $s$, the ray hits $v$ again.
   • The angle of reflection off $s$ is the same as the angle of incidence, which is $105^\circ - 50^\circ = 55^\circ$.
   • As the ray travels towards $v$ again, it will hit $v$ with an angle of $55^\circ$.

So, the angle of incidence with wall $v$ the second time is 55 degrees.

Would you like more details or have any questions? Here are some questions for you to ask:

1. How does the law of reflection work in different scenarios?
2. Can you explain how to calculate angles when multiple reflections are involved?
3. What are the key principles behind geometric optics?
4. How do perpendicular lines influence angles of incidence and reflection?
5. Could you provide more examples of light reflection and refraction?

Tip: Always remember the law of reflection: the angle of incidence is equal to the angle of reflection. This principle is crucial for solving problems involving multiple reflections.