## Arranging Lenses in Increasing Magnitude

This question requires us to understand the relationship between different units of length and how they relate to the size of a lens.

**Understanding the Units:**

**Kilometer (km):**The largest unit, representing 1000 meters.**Meter (m):**A standard unit of length.**Centimeter (cm):**A smaller unit, representing 1/100th of a meter.**Millimeter (mm):**The smallest unit, representing 1/1000th of a meter.

**Arranging the Lenses:**

Based on the above information, we can arrange the lenses in increasing order of magnitude:

**1 mm**(smallest)**1 cm****1 m****1 km**(largest)

**Explanation:**

The size of a lens is directly related to its focal length. A shorter focal length means a smaller lens, while a longer focal length means a larger lens. Therefore, the lens with a 1 mm focal length is the smallest, followed by 1 cm, 1 m, and finally 1 km.

**Important Note:**

While it is technically possible to have lenses with focal lengths in kilometers, they are incredibly large and not commonly used in practical applications.