Concave Mirror- Image
Concave Mirror – magnification and Characteristics
| Type of mirror | Magnification (m) | Characteristics |
| Concave mirror | m =-v/u | Images can be real or virtual, depending on object’s position
Real Images are inverted and virtual images are upright Magnification varies. Greater than 1, image is magnified Less than 1, image is diminished. |
Questions related to Concave Mirror
- Describe how a concave mirror is applied in a shaving mirror?
- Describe the application of reflection in the working of a microscope.
- In what way does the application of reflection pay a role in solar cookers?
- Explain the use of concave mirrors in solar furnaces.
- The image formed by a concave mirror is real, inverted and larger than the object. Where is the object placed?
Answers related to Concave mirror:
- Concave mirror in a shaving mirror produces a magnified, virtual and erect image, facilitating a closer view for shaving.
- A microscope uses concave mirrors to focus light on the slide or specimen, enhancing visibility.
Microscope - A solar cooker uses a concave mirror to focus sunlight onto a cooking vessel, increasing the intensity of heat for cooking.
- Solar furnaces use concave mirrors to concentrate sunlight onto a focal point creating high temperatures for various industrial applications.
- Between F and C.
Concave Mirror – Numerical
NUMERICAL- 1
An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed, so that a sharp focussed image can be obtained? Find the size and the nature of the image.
| object distance (u) | image distance(v) | ho | hi | focal length(f) | nature |
| -27 cm | ? | +7 cm | ? | -18 cm | ? |
| ➡ ⬅
Against (Negative) |
? | ⬆
(positive) |
? | Negative | ? |
Solution:
| u | v | h0 | hi | f | nature |
| Incident light direction is opposite to the measurement from the pole (p) | Incident light direction is opposite to the measurement from the pole | Upwards
above the principal axis |
Downwards
below the principal axis |
Negative
f 0 |
Real
inverted on the same side. |
| ➡ ⬅p
negative |
➡ ⬅p
negative |
⬆
positive |
⬇
Negative |
Negative |
CALCULATING THE IMAGE DISTANCE:
Mirror formula 1/v+1/u=1/f
1/v=1/f-1/u =1/(-18)+1/(27)
=(-3+2)/54 v=-54 cm
Magnification m=-v/u =hi/ho
m=-v/u =(-54)/(-27)=-2
m=hi/ho =hi/7
hi=-14 cm
Real,Inverted,Beyond C,Enlarged
On the same side of the mirror.
Image formation by a concave mirror
When the object is placed between C and F
Concave mirror -Virtual Image Formation
CONCLUSION:
The concave mirror sign convention is a useful tool for understanding and assessing the optics of concave mirrors because it can properly anticipate and interpret the behaviour of light rays reflected by concave mirrors by assigning suitable sign values to pertinent parameters.
We open the door to a deeper understanding of mirror optics and pave the road for further study and invention in this fascinating area by mastering the sign convention.
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