PURPOSE
To determine the characteristics of the images in both converging and diverging mirrors
Hypothesis
Use your understanding of the properties of light to write a hypothesis predicting the characteristics of images in converging and diverging mirrors.
One would hypothesize that concave mirrors will always produce a real image that is inverted and beyond the focus except when the object is located on the focal point, which then it will produce no image, or located in front of the focal point, which then it will produce an upright, virtual image behind the mirror.
MATERIALS
Converging mirror diverging mirror mirror support metre stick with two supports
Candle with holder paper screen chalk
PROCEDURE
1. / Place the two sticks supports under the ends of the metres stick
2. / Place the converging mirror in the mirror support and place this at the 10cm mark.
3. / Find the focus (F) of the mirror. Use a cell phone with the flash light option. Stand far back so that the light will be hitting the mirror “parallel” and then should converge at the focus. To determine this point, hold the white screen partially infront of the mirror and move it back and forth along the metre stick until a clear image forms on the paper (the side facing the mirror). Adjust so that you get a sharp image. Mark “F” on the metre stick using the chalk.
4. / Find the centre of curvature (C). This is located twice the distance from the mirror as the focus. So if the focus is 20cm from the mirror, the centre of curvature is 40cm. Mark a “C” on the metre stick
5. / Place a lit candle beyond C and move the paper screen back and forth to locate a focused real image. Record the characteristics in your chart. Use C and F as reference points when describing image location.
6. / Repeat step 5 with the candle at the other locations indicated in the chart. Record your observation
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10. / CAREFULLY replace the concave mirror with the convex mirror.
Attempt to find an image on the paper screen, record your observations.
9Lolook into the convex mirror and locate the image of the candle, observe and record the image characteristics
Move the candle back and forth. Observe and record any changes in the image.
OBSERVATIONS
Record your observations.
ConcaveObject Location / Size of Image / Attitude of Image / Location of Image / Type of Image
Beyond C / Smaller / inverted / b/w F and C / real
At C / Same size / inverted / At C / Real
Between C and F / larger / inverted / Beyond C / real
At F / No image / N/A / N/A / N/A
Inside F / larger / upright / Behind the mirror / Virtual
Convex
In front of mirror / smaller / upright / Behind mirror / Virtual
ANALYSIS
1What type of image(s) does a converging mirror produce?
It produces both real and virtual images. It produces real images if the object is placed anywhere behind F, no image if at F and virtual if placed in front of F.
2Where must an object be located for a converging mirror to produce a real image?
For a converging mirror to produce a real image, the object must be place beyond the focal point (not on it or in front of it)
3What happens to the size of the image as the object is moved forward towards F?
As the object moves forward towards the focal point, the image gets larger.
4Where must the object be placed for a converging mirror to create a virtual image?
To create a virtual image in a converging mirror, the object must be placed in front of F.
5When using the diverging mirror, why did you not have to follow the same procedure as the converging mirror?
When using a diverging mirror, you do not have to follow the same procedure as the converging mirror because there is only one scenario that is produced and that is: no matter the location of the object in front of the mirror, the image is always upright, virtual, smaller and located behind the mirror. This is because the reflected rays will never intersect in front of the mirror so the reflected rays need to be extended behind the mirror where they will intersect. It is the concave mirror has different scenarios that arise depending on where the object is located.
6A converging mirror has a focus 12cm from the mirror. Predict the characteristics of the image produced if a candle is placed:
-30 cm from the mirror(object is beyond C: Smaller, inverted, b/w F and C, real)
-18 cm from the mirror(object is b/w C and F: larger, inverted, beyond C, real)
-9 cm from the mirror(object is in front of F: larger, upright, behind mirror, virtual)
CONCLUSION
What are the characteristics (SALT) of the images in the converging and diverging mirrors. Were your predictions correct?
Concave:
object is beyond C: Smaller, inverted, b/w F and C, real
object is at C: same size, inverted, at C, real
object is b/w C and F: larger, inverted, beyond C, real
object is at F: no image
object is in front of F: larger, upright, behind mirror, virtual
Convex: Object is in front of the mirror: image is larger, upright, behind mirror, virtual
Indeed our hypothesis is correct and followed the theoretical patterns of images reflected in curved mirrors.