Educational worksheet demonstrating the concept of refraction with a hands-on experiment.

Problem Description:

The task involves understanding the phenomenon of refraction using a simple experiment with a pencil or straw in a cup of water. The goal is to observe how light bends when it passes from air into water, causing the pencil or straw to appear bent.

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Solution and Explanation:

#### Step 1: Understanding Refraction
Refraction is the bending of light as it passes from one medium (e.g., air) into another medium (e.g., water). This bending occurs because light travels at different speeds in different media. Specifically:
- Light travels faster in air than in water.
- When light enters a denser medium (like water), it slows down and changes direction.

The degree of bending depends on the index of refraction of the two media involved. Water has a higher index of refraction than air, so light bends toward the normal (an imaginary line perpendicular to the surface) when entering water.

#### Step 2: Observing the Experiment
In the experiment:
1. Place a pencil or straw in a cup of water.
2. Look at the pencil or straw through the water.
3. Notice that the pencil or straw appears to be bent where it enters the water.

This apparent bending is due to refraction. Here's why:
- Light rays from the part of the pencil above the water travel straight through the air.
- Light rays from the part of the pencil below the water enter the water and slow down, causing them to bend toward the normal.
- Your eyes interpret the bent light rays as if they traveled in a straight line, leading to the illusion that the pencil is bent.

#### Step 3: Positioning the Pencil at Different Angles
When you position the pencil or straw at different angles:
- If the pencil is vertical (perpendicular to the surface of the water), the bending effect might be less noticeable because the angle of incidence is small.
- If the pencil is tilted at an angle, the bending effect becomes more pronounced because the angle of incidence is larger.

#### Step 4: Observing the Distortion
As you change the angle of the pencil:
- At certain angles, the distortion (bending) may appear more significant.
- At other angles, the distortion may seem lessened, especially when the pencil is nearly vertical.

This variation in distortion is directly related to the angle at which light enters the water. The greater the angle of incidence, the more the light bends, and thus the more pronounced the distortion.

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Final Answer:

When positioning the pencil or straw at different angles:
- There is no single "point" where the distortion is completely eliminated unless the pencil is perfectly vertical (perpendicular to the water surface).
- However, the distortion is lessened when the pencil is closer to being vertical because the angle of incidence is smaller, resulting in less bending of light.

Thus, the key observation is that the distortion is minimized when the pencil is vertical.

$$
\boxed{\text{The distortion is lessened when the pencil is positioned vertically.}}
$$