key term - Principal Axis

Definition

The principal axis of a mirror is the central line or axis of symmetry that passes through the center of curvature of the mirror. It is the primary axis along which the mirror's optical properties are defined and image formation occurs.

5 Must Know Facts For Your Next Test

1. The principal axis is the reference line used to describe the location and properties of images formed by a mirror.
2. The distance between the mirror's surface and its center of curvature is equal to the mirror's radius of curvature.
3. For a concave mirror, the principal axis passes through the center of curvature and the focal point, which is located in front of the mirror.
4. For a convex mirror, the principal axis passes through the center of curvature and the focal point, which is located behind the mirror.
5. The principal axis is used to determine the position, size, and orientation of the image formed by a mirror relative to the object.

Review Questions

• Explain the relationship between the principal axis, center of curvature, and radius of curvature of a spherical mirror.
  • The principal axis of a spherical mirror is the central line of symmetry that passes through the center of curvature of the mirror. The center of curvature is the point at which the radius of curvature, which is the distance from the mirror's surface to its center of curvature, intersects the principal axis. The radius of curvature determines the mirror's focal length and the degree of convergence or divergence of light rays reflected from the mirror's surface.
• Describe how the principal axis is used to determine the properties of the image formed by a concave and a convex mirror.
  • For a concave mirror, the principal axis passes through the center of curvature and the focal point, which is located in front of the mirror. The position, size, and orientation of the image formed by a concave mirror relative to the object can be determined using the principal axis. For a convex mirror, the principal axis passes through the center of curvature and the focal point, which is located behind the mirror. The principal axis is used to analyze the virtual, upright, and smaller image formed by a convex mirror.
• Analyze how the location of the object relative to the principal axis affects the characteristics of the image formed by a spherical mirror.
  • The location of the object relative to the principal axis of a spherical mirror is a crucial factor in determining the properties of the resulting image. If the object is placed at a distance greater than the mirror's focal length and on the principal axis, a real, inverted, and diminished image will be formed on the opposite side of the principal axis. If the object is placed between the mirror and its focal point, a virtual, upright, and magnified image will be formed on the same side as the object. The principal axis serves as the reference line for analyzing these image characteristics and their relationship to the object's position.

Related terms

Center of Curvature:

The center of curvature is the point at which the radius of curvature of a spherical mirror intersects the principal axis. It is the point around which the mirror's surface is curved.

Radius of Curvature:

The radius of curvature is the distance from the mirror's surface to its center of curvature, which determines the mirror's focal length and the degree of convergence or divergence of light rays.

Focal Point:

The focal point of a mirror is the point on the principal axis where parallel rays of light converge or appear to diverge after reflection from the mirror's surface.