Educational worksheet on refraction and convex lenses, featuring diagrams of light rays passing through glass and a convex lens, with instructions to complete and label the diagrams.

Problem Analysis and Solution

The provided worksheet focuses on refraction and convex lenses. Let's break it down into sections and solve each part step by step.

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#### Section 1: Refraction Diagrams
The task is to identify which diagrams correctly depict the refraction of light as it passes through a medium (e.g., glass block).

##### Diagrams Provided:
- A: Light entering a glass block at an angle.
- B: Light traveling straight through a glass block.
- C: Light entering a glass block at an angle.
- D: Light entering a glass block at an angle.
- E: Light exiting a glass block.

##### Key Principles of Refraction:
1. When light travels from a less dense medium (e.g., air) to a more dense medium (e.g., glass), it bends toward the normal.
2. When light travels from a more dense medium to a less dense medium, it bends away from the normal.
3. The angle of incidence and the angle of refraction are related by Snell's Law: \( n_1 \sin \theta_1 = n_2 \sin \theta_2 \).

##### Analysis of Each Diagram:
- A: Correct. Light bends toward the normal when entering the glass block.
- B: Incorrect. Light should bend when entering or exiting the glass block unless it is perpendicular to the surface.
- C: Correct. Light bends toward the normal when entering the glass block.
- D: Correct. Light bends toward the normal when entering the glass block.
- E: Correct. Light bends away from the normal when exiting the glass block.

##### Correct Diagrams:
- A, C, D, and E are correct.

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#### Section 2: Completing Refraction Diagrams
The task is to complete the diagrams by drawing the refracted rays as light passes through a glass block. Use a ruler to ensure accuracy.

##### Guidelines for Drawing Refracted Rays:
1. Draw the incident ray approaching the glass block.
2. At the boundary, draw the normal (a dashed line perpendicular to the surface).
3. Apply the principle of refraction:
- If light enters the glass block, it bends toward the normal.
- If light exits the glass block, it bends away from the normal.
4. Ensure the angles are consistent with the principles of refraction.

##### Steps to Complete Each Diagram:
1. Diagram 1: Light entering the glass block at an angle.
- Draw the incident ray.
- Draw the normal at the point of incidence.
- Bend the ray toward the normal inside the glass block.
2. Diagram 2: Light exiting the glass block.
- Draw the incident ray inside the glass block.
- Draw the normal at the point of emergence.
- Bend the ray away from the normal as it exits the glass block.
3. Diagram 3: Light entering the glass block at an angle.
- Follow the same steps as in Diagram 1.
4. Diagram 4: Light exiting the glass block.
- Follow the same steps as in Diagram 2.

##### Solution:
- Use a ruler to draw straight lines for the rays.
- Ensure the angles are consistent with the principles of refraction.

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#### Section 3: Ray Diagram for Light Exiting the Block
The task is to complete the ray diagram showing what happens when light exits the glass block and label the angles.

##### Given Information:
- Incident angle in air: \( 30^\circ \)
- Refracted angle in glass: \( 25^\circ \)

##### Steps to Complete the Diagram:
1. Draw the Incident Ray: Extend the incident ray from the ray box into the glass block.
2. Draw the Refracted Ray Inside the Glass Block: Use the given angle of \( 25^\circ \) relative to the normal.
3. Draw the Emergent Ray: As light exits the glass block, it bends away from the normal. Use Snell's Law or the principle of reversibility to determine the angle.
- The angle of incidence in glass is equal to the angle of refraction in air when the light re-enters the air.
4. Label the Angles: Label the angles between the rays and the normal both inside and outside the glass block.

##### Solution:
- The emergent ray will bend away from the normal.
- The angle of refraction in air will be \( 30^\circ \) (same as the incident angle in air due to reversibility).

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#### Section 4: Convex Lens
The task involves completing a diagram of a convex lens, labeling it, and answering questions about its behavior.

##### Part 1: Completing the Diagram
The diagram shows parallel rays converging after passing through a convex lens. Complete the diagram by extending the rays to show where they meet.

##### Part 2: Labeling the Diagram
Label the following:
- Focus/Focal Point: The point where the rays converge.
- Focal Length: The distance from the center of the lens to the focal point.

##### Part 3: Completing Sentences
1. When light rays pass through a lens, they are...
- Refracted (bent as they pass through the lens).
2. A... lens is fat in the middle. It brings the rays of light closer together – we can say that they...
- Convex lens; converge (the rays come closer together).
3. The rays meet at a point called the...
- Focal point (the point where the rays converge).

##### Solution:
- Completed Diagram: Extend the rays to show convergence at the focal point.
- Labels: Mark the focal point and focal length.
- Sentences:
1. Refracted
2. Convex; converge
3. Focal point

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Final Answer:

\[
\boxed{A, C, D, E}
\]
(For the other sections, follow the detailed steps above to complete the diagrams and answer the questions.)