# How to determine the position of the hearth?

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### How to determine the position of the hearth?

the **foyer** is a point on the principal axis where the incident rays parallel to the principal axis converge, or the place from which these rays appear to originate (in the case of a diverging lens).

### How to find the position of the lens?

If is positive, then the image is straight (i.e. in the same direction as the object). If is negative, then the image is inverted with respect to the object. A real inverted image can be obtained after the **lens** if the object is placed before the focus object of the **lens** convergent.

### Where is the focal point of a converging thin lens located?

The focal length of a **thin converging lens** the **foyer** picture of the **lens** to **situates** after its optical center in the direction of light propagation. Therefore, the algebraic distance \overline{OF’} **is** positive. The focal length of a **convergent lens is** positive.

### What is the focus of the lens?

the **foyer** object is the point from which the light rays that emerge from the **lens** parallel to the optical axis. the **foyer** object is the mirror image of point F’ with respect to the optical center.

### How to determine the meaning of an image?

**the sense of the’image relative to the object also depends on the value of the magnification:**

- If γ>0 the
**image**is therefore in the same**sense**that the object; - If γ

### What is the focal point of a lens?

**Focus of a lens** : The **hearth is** a fixed point through which pass all the light rays coming from infinity.