Sometimes, a crackling sound is heard while taking off a sweater during winters. Explain.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Context**: During winter, when we wear sweaters, the material of the sweater can come into contact with our skin. This contact is often accompanied by movement, such as pulling the sweater off.

2. **Friction Between Surfaces**: When you take off the sweater, there is friction between the fabric of the sweater and your skin. Friction is a force that occurs when two surfaces rub against each other.

3. **Charge Generation**: As the sweater is pulled away from your body, electrons can be transferred from one surface to the other due to this friction. This process is known as triboelectric charging. Depending on the materials involved, one surface may lose electrons and become positively charged, while the other gains electrons and becomes negatively charged.

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