# Experimenting with a Concave Mirror and a Candle

• jnimagine
In summary, an experiment was conducted using a concave mirror and a candle. When the candle was placed between the vertex and the focus of the mirror, a virtual image appeared behind the mirror. The image distance was measured approximately by pointing a finger and was found to be 6.0cm. However, when using the mirror equation to calculate the focus, a negative answer was obtained. This could be due to human errors in measuring the image distance accurately. Additionally, the image distance should be almost the same as the object distance in this case.
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?

Yes, the virtual image did form at -12.7 cm according to the formula (which do work by the way!).

Locating a virtual image by parallax (or by finger as you say) can be tricky. Especially if you do not know what you are actually doing and did not had a bit of practice.

So I would think that you did not succeed too well at pointing at the correct position behind the mirror, that is you had to hold your finger two times futher backwards.

I would say that there are a few factors that could potentially account for the discrepancy between the measured and calculated focus in this experiment.

Firstly, it is possible that there were some human errors in measuring the image distance accurately. It is important to be precise and careful when conducting experiments, as even small errors can have a significant impact on the results.

Secondly, the mirror equation assumes certain ideal conditions, such as a perfectly spherical mirror and a point source of light. In reality, these conditions may not be met, which could also contribute to the discrepancy between the measured and calculated focus.

Lastly, it is important to consider the concept of parallax when measuring the image distance. Parallax refers to the apparent shift in position of an object when viewed from different angles. In this experiment, pointing a finger towards where the image might be could introduce some parallax error, leading to an inaccurate measurement of the image distance.

To address these potential factors, it would be beneficial to repeat the experiment multiple times and take multiple measurements to ensure accuracy. Additionally, using more precise tools such as a ruler or measuring tape could also improve the accuracy of the measurements. Overall, it is important to carefully consider and control all variables in an experiment to obtain reliable and accurate results.

## 1. How does a concave mirror affect the light from a candle?

A concave mirror reflects light inwards towards a central focal point. When a candle is placed in front of a concave mirror, the light from the candle is reflected and focused at this focal point, creating a larger and brighter image of the candle.

## 2. What is the purpose of using a candle in this experiment?

The candle serves as a source of light to be reflected by the concave mirror. Its small size and ability to produce consistent light make it ideal for this experiment.

## 3. How does the distance between the candle and the concave mirror affect the image produced?

The closer the candle is to the concave mirror, the larger and brighter the image will be. As the distance increases, the image will become smaller and dimmer.

## 4. Can a concave mirror be used to create different types of images with the candle?

Yes, by adjusting the distance between the candle and the concave mirror, different types of images can be created. For example, moving the candle closer to the mirror will produce a larger and brighter image, while moving it further away will create a smaller and dimmer image.

## 5. Is it necessary to use a specific type of concave mirror for this experiment?

Not necessarily, any type of concave mirror can be used as long as it has a smooth surface and a reflective coating. However, for more accurate results, it is recommended to use a concave mirror with a smaller curvature radius.

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