How Do Concave Mirrors Form Real or Virtual Images?

[mmg0789]

how can you tell when the image will become real or virtual in a concave mirror, the distance?..i'm not sure

thanks in advance

*edit*
oh i think i know..is it the magnification, if the magnification is more than 1 then that means its virtual since it would be upright and a bigger image

is that right?

 

[Hootenanny]

This is correct;

how can you tell when the image will become real or virtual in a concave mirror, the distance?

Using the standar equation for a mirror;

$$\frac{1}{d_{O}} + \frac{1}{d_{i}} = \frac{1}{f}$$

When $d_{i}$ is positive, the image is real; if it is negative the image is virtual. $d_{i}$ is the horizontal displacement of the image from the centre of the mirror. $d_{O}$ is the horizontal displacement of the object from the centre of the mirror and $f$ is the focal length of the mirror (which is positive for a concave mirror).

It is possible it have a real image that is larger than the object. What is the definition of a real and virtual image?

More information is available here;
http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/mirray.html#c3

 

[arunbg]

Actually if the magnification is +ve , the image is virtual.
-ve->real
(As per new Cartesian sign convention)

 

[Hootenanny]

Actually if the magnification is +ve , the image is virtual.
-ve->real
(As per new Cartesian sign convention)

I agree, that's why I said above

t is possible it have a real image that is larger than the object.

I did forget to mention however, that the image would be inverted.

~H