What are we doing?
build a gas thermometer, and then explain the physical phenomena of the operation of this instrument.
Materials:
"A large glass jar with lid.
-plastic capillary tube of a ballpoint pen (Bic type). Plastilina
-Fastix or type of sealer.
-blue or black ink or dye.
Procedure:
If the capillary has some ink pen, wash well. You may want to use alcohol.
In the center of the bottle cap to make a hole Like smaller diameter than the capillary.
Pass the tube through the hole and secure it so that they are two or three inches of the inside of the lid. Union with clay seals or sealant.
Fill a bowl with water. Mix some ink or dye to color. Touches the water with either end of the capillary. Due to the capillary column of water will rise through it. Separate tube plate and notes that in its interior has been a drop.
Carefully drop is moving toward the center of the capillary, trying not to be separated into several droplets.
Place the bottle cap. Due to increased internal pressure is likely to drop operation to move above. In this case start over with a new drop, since the objective is that when you put the lid on the jar the drop is about half of the tube (see figure).
already have your gas thermometer. the temperature indicator is the position of the drop in the capillary.
To prove it: Place the thermometer on a hot plate. A few moments you will see that the drop of water moves upward. Take the thermometer out of hot water and place it in cold water. You will see that the drop moves down.
Explanation:
drop behavior in the capillary is explained as follows: when the thermometer immersed in hot water the air inside is heated. When heated, the air pressure inside the container increases slightly with respect to atmospheric pressure and pushes the droplet upward airflow. When the thermometer immersed in cold water cools the air, the pressure decreases inside and then outside pressure pushes the drop down.
This thermometer is not very accurate but has the advantage that it is quite sensitive to temperature changes. If you take the glass bowl with both hands, you will observe that the drop goes and then if you leave it on the table, really coming down to its original position.
Think about the similarities between this thermometer and one mercury.
0 comments:
Post a Comment