Science Experiments

Archive for January, 2009

How to find the humidity using a hygrometer

To find the percentage of humidity, follow the nearest curved dotted lines to the right of the chart. If the dry bulb temperature were 70 degrees F, for example, and the web bulb temperature were 62 degrees F, you would find the relative humidity would be 60% which is well within the comfort zone.

Meteorology and the sling hygrometer

What is Meteorology?

Meteorology is the science of weather prediction. Meteorology involves many techniques. However, the accuracy of weather prediction can still be greatly improved with better technology.

Humidity is the amount of water vapor in the air. Humidity makes all the difference in determining whether a warm day is pleasant or muggy and a cool day refreshing or clammy. Meteorologists find the figure for relative humidity by comparing the amount of moisture in the air with the amount it could hold if it were saturated at the same temperature. This is the idea behind a hygrometer.

How to make a Hygrometer

Have you ever wondered how to make a hygrometer? Learning how to make a hygrometer is not difficult. However the how to make a Hygrometer science experiment is more for a Middle School Science Labs project, rather than a Fun Kid Experiment at home.

Once you have learned how to make a hygrometer, your knowledge will come in handy.

All you need to learn how to make a hygrometer is the following:

What you need to make a hygrometer

Learn how to make a hygrometer by doing the following science experiment.

• 2 identical thermometers with rigid backings
• 1/2 x 6 inch (1.25 x 15 cm) dowel, cut down as needed
• 1.5 inch wood screw
• washer
• carpenter’s glue
• cotton
• drill

About the sling hygrometer

The sling hygrometer will give two simultaneous temperature readings. With the aid of the hygrometer chart, you can determine relative humidity with reasonable accuracy. In this Middle School Science Labs experiment, we divide the how to make a hygrometer experiment into two parts.

How to make a hygrometer Part I

• Attach two thermometers back to back with carpenter’s glue. If the thermometers have plastic backings, use epoxy glue instead of carpenter’s glue.
• Allow glue to dry.
• Drill a hole through the two thermometers at the top of the mountings.
• Drill a hole at the wooden dowel’s top.
• Attach the thermometers to the dowel with a 1.5 inch (3.75 cm) wood screw, placing the washer between screw and dowel. Do not tighten the screw all the way. The thermometers should swing freely around.

How to make a hygrometer Part 2

• Stuff cotton under the top thermometer’s bulb, fastening it with two thumbtacks if necessary.
• Moisten the cotton with water.
• Holding the dowel, whirl the hygrometer around for 30 seconds before recording the temperature on both thermometers. The wet bulb should now read a lower temperature than the dry bulb since heat is required to evaporate the water.
• Using the hygrometer chart, locate the dry bulb temperature at the bottom.
• Locate the wet bulb temperature at the top, where indicated by the diagonal lines.
• Trace these two lines until they intersect.

Question: How to do my science fair EXPERiMENT ?

Ok . Well im doing my science fair project on The effect of salt Water On Alfalfa Plants . Today my teacher gave me alfalfa seeds to take home and now im on my own . I have no idea what to do now . IM SO NERVOUS ! How often do i water my plants ? How much salt should i mix with the water ? How much soil should i use ? I’ll admit i am kind of slow ; LOL ; but i need step by step directions ! PLEEEEEEASEEE & QUICK !!!

Answer: Hi Faith,

Take a deep breath and relax. I am a research scientist who does plant experiments everyday for my job.

What you need:

9 small plant pots about 4 inches in diameter.
Some seed raising potting mix.
Your alfalfa seeds
A measuring cup
Water
Salt
Labels for the pots
Scales for weighing small amounts.

Method

1. Put potting mix into your 9 pots. Try and make sure they are all fairly equal.
2. Label 3 pots “control” Label another three “low dose” and the final three “high dose”
3. Weigh out 9 equal amounts of alfalfa seed and sprinkle onto the soil surface in each pot.
4. Very gently water each pot with 100ml of water.
5. Place your pots in a warm, light position (not in full sunlight)
6. Each day, water with 100ml of water. Remember, the water is going to drain through the pots and come out the bottom so you might want to do this over a sink.
7. After a week or so, you should have a nice crop of alfalfa in each pot so its time to start your treatments.
8. Control pots – Each day, water each pot with 100ml of plain water.
Low dose – Each day, water each of these three pots with 100ml of water with 1/2 a teaspoon of salt dissolved in it. So that is 100ml + 1/2 teaspoon for each pot.
High dose – each day, water each pot with 100ml of water with 2 teaspoons of salt dissolved in it.
9. Starting the 2nd day after you begin applying your treatments, you need to start recording some data. This means you need to make a note of your observations for each pot. You might like to record a percentage of how many seedlings have died. This is just a visual estimation based on area. You might like to record observations of leaf shapes or any odd growth patterns. You need to do this every day just prior to applying that day’s treatments. If you do this for a week, you should get some pretty dramatic results.
10. Present your data in an interesting way. Maybe some graphs. Definetely take photos.

11. Finally, you need to discuss what it is you are observing. You might want to google words like “turgor” “osmosis” “plasmolysis” and see how you go.

Hope I’ve been some help.

Science Video 3 – Soil Erosion – French Version