# Concave mirror and virtual image

• jnimagine
In summary, the experiment used a concave mirror and a candle to observe a virtual image appearing behind the mirror when the candle was placed between the vertex and focus of the mirror. The measured image distance was approximately 6.0cm (-6.0 when used in the mirror equation) and the object distance was 6.35cm. However, when using the mirror equation to calculate the focus, a negative answer was obtained which was not close to the actual focus of 12.7cm. The discrepancy may be due to human errors in measuring the image distance or other factors. The image distance should be the same as the object distance for a given focal length and object distance, but the parallax method used to locate the image may
jnimagine
we used a concave mirror and a candle for an experiment
when the candle wa placed between the vertex and the focus of the mirror (f=12.7cm) a virtual image appeared behind the mirror.
We measure the image distance approximately by pointing a finger towards where the image might be and got 6.0cm (-6.0 when used in mirror equation) and the object was at 6.35cm. However, when I use the mirror equation to calculate the focus, i get a negative answer that is not even close to the actual focus 12.7cm. Do u think this is just due to human errors of not measuring the image distance accurately or is there some other factors that can account for this? OR is the image distance supposed to be almost the same as the object distance in this case?

For the given focal length (12.7) and object distance (6.35), you should get an image distance of -12.7.

So you must have either put the object in the wrong location, or else measured the image distance incorrectly. It sounds like you used the "parallax method" to locate the image. That is, you moved your finger around until you found a location where it appeared to line up with the image no matter what angle you looked at them from. I find that many students have trouble with this at first.

It is likely that the difference in the measured image distance and the calculated focus is due to human error in measurement. The mirror equation is an idealized mathematical equation and does not take into account factors such as imperfections in the mirror or slight variations in the placement of the candle and finger. Additionally, in this experiment, the object distance is close to the focal length of the mirror, so the image distance should also be close to the object distance. However, it is normal for there to be slight variations in the measured values due to experimental limitations. It is important to repeat the experiment multiple times and take an average of the values to reduce the impact of human error.

## 1. What is a concave mirror?

A concave mirror is a type of curved mirror where the reflective surface is curved inwards, like a bowl. This causes light rays that hit the mirror to converge at a focal point, creating a magnified or inverted image.

## 2. What is a virtual image?

A virtual image is an image that appears to be behind a mirror or lens, and cannot be projected onto a screen. In the case of a concave mirror, the virtual image is created by the convergence of light rays at the focal point.

## 3. How does a concave mirror form a virtual image?

A concave mirror forms a virtual image by reflecting light rays that hit the mirror's surface. These reflected rays converge at a focal point and create an image that appears behind the mirror.

## 4. Can a concave mirror create a real image?

Yes, a concave mirror can create a real image under certain conditions. If the object is placed beyond the focal point, the reflected light rays will converge and create a real image in front of the mirror. However, the image will be inverted.

## 5. What are some practical applications of concave mirrors and virtual images?

Concave mirrors and virtual images have many practical applications, including use in telescopes, reflector headlights, and makeup mirrors. They are also used in medical imaging devices such as endoscopes and dental mirrors.

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