The problem presented asks about the behavior of a light beam reflecting off a flat mirror. Specifically:

• A light beam initially falls on a mirror at an angle of $60^\circ$.
• The mirror is rotated by an angle of $18^\circ$ in the clockwise direction, while the incident beam remains in the same direction.
• The question is to determine the angle that the reflected beam makes with the mirror after this rotation.

Key Concept: Law of Reflection

The law of reflection states that the angle of incidence is equal to the angle of reflection. When the mirror rotates, the angle between the incident light and the surface changes, and the reflected angle adjusts accordingly.

Impact of Mirror Rotation:

When the mirror is rotated by an angle $\theta$, the angle of the reflected beam changes by twice that angle, i.e., $2\theta$. This means if the mirror is rotated by $18^\circ$, the reflected beam will rotate by $2 \times 18^\circ = 36^\circ$.

Solving:

• Initial angle of incidence: $60^\circ$.
• After rotation, the total change in the angle of the reflected beam will be $36^\circ$.

Thus, the new angle of the reflected beam will differ by $36^\circ$ from its original direction.

The correct answer, based on the law of reflection, is 48° as the beam will change direction by 36° from its previous 60°.

Would you like more detailed information, or do you have any further questions?

Related Questions:

1. How is the law of reflection applied to a curved mirror?
2. What happens if the incident angle is changed while the mirror remains fixed?
3. How does the material of the mirror affect the reflection?
4. How does the rotation of the mirror affect the reflected beam if the rotation direction is reversed?
5. What would happen to the reflected beam if the incident beam is also rotated?

Tip:

Remember, any rotation of the mirror causes the reflected ray to move by double the angle of rotation!