Question

While doing experiment with candle to find focal length of a concave mirror, the candle is placed between
A. Beyond focus
B. Pole and focus
C. At focus
D. At infinity ​

Answer 1

Answer:

The answer is option D. At infinity

Answer 2

To find focal length of a concave mirror, the candle is placed at (d) infinty.

• A concave mirror forms a real inverted image of the object.
• An object kept at infinity (distance much greater than focal length of mirror) will have its image formed at the focus.
• To determine the focal length of the mirror:

1. Hold a candle very far from the mirror.
2. Take a screen (white paper) and move it back and forth close to the mirror.
3. Obtain a sharp inverted image of the candle on the screen.
4. Measure this distance of screen from the pole of mirror.
5. The reading is the focal length of the mirror.