# Converging & Diverging Lenses(Edexcel A Level Physics)

Author

Ashika

Expertise

## Converging & Diverging Lenses

• A lens is a piece of equipment that forms an image by refracting light
• There are two types of lens:
• Convex
• Concave

#### Convex Lenses

• In a convex lens, parallel rays of light are brought to a focus by refraction
• This point is called the principal focus

• This lens is sometimes referred to as a converging lens
• The distance from the lens to the principal focus is called the focal length
• This depends on how curved the lens is
• The more curved the lens, the shorter the focal length

The focal length is the distance from the lens to the principal focus

#### Concave Lenses

• In a concave lens, parallel rays of light are made to diverge (spread out) from a point
• This lens is sometimes referred to as a diverging lens

• The principal focus is now the point from which the rays appear to diverge from

Parallel rays from a concave lens appear to come from the principal focus

#### Exam Tip

To remember which lens is converging or diverging, think of the following: Convex lens = Converging

To remember which lens is which, a concave lens goes in at the middle, like a cave. Okay, not a very exciting cave, but all the same...

### Get unlimited access

to absolutely everything:

• Unlimited Revision Notes
• Topic Questions
• Past Papers