8. Complete Activity 11.8 (Page 131). Repeat Activity 11.7 now with a convex mirror in place of a concave mirror. Record your observations in a Table similar to Table 11.1
Answer: The activity can be carried out as follows:
Aim: To study the images of a candle formed by a convex mirror by positioning it at varying distances from the mirror.
Materials Required: Convex mirror, stand, white paper sheet, cardboard sheet (about 15 cm × 10 cm), lighted candle.
Procedure:
(i) Fix the convex mirror on a stand (any arrangement to keep the mirror steady would do) and place it on a table.
(ii) Make the screen bypasting the piece of white paper on the 15 cm × 10 cm cardboard sheet.
(iii) Keep the lighted candle on the table at a distance of about 50 cm from the mirror and try to obtain the image of the flame on the screen. If necessary, move the screen till a sharp image of the flame is obtained. The screen should not obstruct the light from the candle falling on the mirror. Observe the type of image that is formed on the screen.
(iv) Now move the candle towards the mirror and place it at distances of 40 cm, 30 cm, 20 cm, 10 cm and 5 cm from it. In each case try to obtain the image on the screen and record the details of each image in Table 11.1.
Observations:
The details of the image of the flame for each distance are recorded in Table 11.2 below:
Table 11.2 Image formed by a convex mirror for object placed at different distances from it
| Distance of the object from the mirror | Smaller/larger than the object | Character of the image | |
| Inverted/Erect | Real/Virtual | ||
| 50 cm | Much smaller than object | Erect | Virtual |
| 40 cm | Smaller than object | Erect | Virtual |
| 30 cm | Smaller than object | Erect | Virtual |
| 20 cm | Smaller than object | Erect | Virtual |
| 10 cm | Smaller than object | Erect | Virtual |
| 5 cm | Smaller than object | Erect | Virtual |
The images formed for all the distances 50 cm, 40 cm, 30 cm, 20 cm, 10 cm and 5 cm are the same. The size of the image increases as the candle is brought closer to the convex mirror, however it is still smaller than the candle itself.
The image formed at a certain distance is shown below as an example:
Conclusions: We conclude that:
- The image formed by a convex mirror is always virtual, erect and diminished and forms behind the mirror.
- The size of the image progressively increases with decreasing distance.
Related Links:
Solution to Extended Learning Problem 1
Solution to Extended Learning Problem 2
Solution to Extended Learning Problem 3
Solution to Extended Learning Problem 4
Solution to Extended Learning Problem 5
Solution to Extended Learning Problem 6
Solution to Activity 11.1
Solution to Activity 11.2
Solution to Activity 11.3
Solution to Activity 11.4
Solution to Activity 11.5
Solution to Activity 11.6
Solution to Activity 11.7
Solution to Activity 11.8
Solution to Activity 11.9
Solution to Activity 11.10
Solution to Activity 11.11
Solution to Activity 11.12
