Name two commonly used polarisers used to polarises light.

Explanation

To answer the question about commonly used polarizers, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Polarizers**: Polarizers are materials that convert unpolarized light into polarized light. Unpolarized light consists of waves vibrating in multiple planes, while polarized light has waves vibrating in a single plane.

2. **Identifying Common Polarizers**: There are several materials that are commonly used as polarizers. Two of the most well-known and widely used polarizers are:
- **Calcite**: A naturally occurring mineral that can polarize light due to its birefringent properties.
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