Page 109 - Biology - XII

Results

1. The white cards turn black or remain white depending upon the density of the smoke.
2. Some cards are white and some are blackened to various percentages.
3. When the accelerator of the vehicle is raised, the deposits or blackness of the card is more.

Observation Table
Smoke density by Ringelmann scale

S. No. Source of smoke % of blackness Ringelmann scale no. Inference

1. Scooter

2. Car

3. Scooterette

4. Motorcycle

Card

Smoke

Fig. 7.2: Measuring the smoke density of a scooter when its engine is on.

Conclusion
1. The smoke emitted by ________ has maximum smoke density. It is Ringelmann Scale No. ________ .
2. The smoke emitted by ________ has the least/minimum smoke density. It is Ringelmann Scale
No. ________ .
Measurement of smoke density on the Ringelmann scale

1. White smoke/transparent smoke — No. 0
2. Intermediate blackness smoke — No. 1–4
3. Totally black opaque smoke — No. 5

Precautions
1. Place the card sheets fairly close to the source of smoke.
2. Keep your fi ngers/card away from direct fi re.

108