Semi Circular Glass Slab

Quick answer: The LabEquip Semi Circular Glass Slab is an optical component used to demonstrate refraction, critical angle and total internal reflection. Its curved and plane faces let students isolate refraction at a single flat surface, making it a clear teaching tool for secondary-school, college and university physics labs.

Product Description

This slab has two different optical boundaries: one curved face and one plane face. When a light ray is directed through the centre of curvature toward the curved surface, it enters or leaves that surface close to the normal, so very little refraction happens there.

This geometry lets students focus on refraction at the flat surface only, and investigate how the emergent ray changes as the angle of incidence increases – including the point where the ray grazes along the flat surface (the critical angle) and where total internal reflection begins. The exact glass composition, radius, thickness and optical surface quality are not confirmed in this listing, so we have not invented these values. Please verify these details with our sales team before combining the slab with other apparatus.

Specifications

Suggested Procedure

• Place the slab flat-side down on paper and trace its outline, marking the centre of the flat face.
• Direct a narrow light ray toward the centre of the flat face through the curved surface.
• Mark the incident and emergent rays, then measure the angle of incidence and angle of refraction at the flat face.
• Gradually increase the angle of incidence and observe the emergent ray weaken and eventually disappear beyond the critical angle.
• Record the critical angle where total internal reflection begins, and repeat at different angles for comparison.

Safety Note

Handle the glass slab carefully; edges may be sharp and it can chip or crack if dropped. Never look directly into the light source used for the experiment.

Care & Maintenance

• Clean both faces with a soft, lint-free cloth; avoid abrasive materials.
• Store the slab flat in a padded case to protect the curved and flat surfaces.
• Inspect for cracks or chips before each use and discontinue use if damaged.

Why Choose LabEquip

LabEquip (The Lab Equipment Pvt Ltd) supplies physics, chemistry, biology and STEM laboratory equipment to schools, colleges and training institutes. Pair this slab with our Rectangular Optical Grade Glass Slab or Ray Optics Kit for a complete refraction study set, or see our Laser Optics Experiment Tank Kit for broader ray-optics work. Visit our homepage to browse the full physics lab equipment range, and ask our sales team to confirm the exact glass grade before you order.

Frequently Asked Questions

What does the Semi Circular Glass Slab demonstrate?

It demonstrates refraction at a flat surface, the critical angle, and total internal reflection, using its curved face to minimise refraction on entry.

Why does the curved face reduce refraction?

When the light ray is aimed through the centre of curvature, it meets the curved surface close to the normal (perpendicular), so it passes through with very little bending, letting students isolate refraction at the flat face.

What is the critical angle for this slab’s glass?

The exact glass composition and refractive index are not stated in this listing, so we have not invented a critical-angle figure. Please confirm with our sales team before a quantitative experiment.

How should I clean and store the slab?

Clean both faces with a soft, lint-free cloth, avoid abrasive materials, and store the slab flat in a padded case to protect the curved and flat surfaces.

Last Updated: September 2026