Introduction: (Initial Observation)
Living things are constantly being exposed to radiation. This exposure comes from natural sources as well as man-made sources. Radiation exposure can have both beneficial and harmful effects on living things. This project attempts to discover the effects of X ray radiation on the growth and development of radish seeds. We suggest to use X rays because they are a very common form of man-made radiation. However if you don’t have access to X-Ray radiation source, you can experiment on Ultra Violet, gamma rays or other types of radiations.
Note: This project can be done in many different ways. You have a lot of different choices for plant or seed as well as many choices for radiation. In our example we have used X-Ray and exposure has has happened only on the seed. Usually you don’t expect X-Ray and gamma rays in a farm or in a green house, so there is no need to test the exposure of actual plant to these type of radiation. However if you select UV as your radiation, you will expose the plant itself to UV by lighting up a UV light above your plants.
Information Gathering:
Find out about X-Ray and other types of radiations. Read books, magazines or ask professionals who might know in order to learn about the effect of different radiations on human and plant life. Keep track of where you got your information from.
X-rays are like light in that they are electromagnetic waves, but they are more energetic so they can penetrate many materials to varying degrees. When the X-rays hit the film, they expose it just as light would. Since bone, fat, muscle, tumors and other masses all absorb X-rays at different levels, the image on the film lets you see different (distinct) structures inside the body because of the different levels of exposure on the film.
Roentgen (R)
The roentgen (R) is a unit of radiation exposure in air. It is defined as the amount of x-ray or gamma radiation that will generate 2.58E-4 coulombs per kilogram of air at standard temperature and pressure.
rad
RAD stands for Radiation Absorbed Dose. The rad is the amount of radiation that will deposit 0.01 Joules of energy in a kilogram of material.
A roentgen in air can be approximated by 0.87 rad in air, 0.93 rad in tissue, and 0.97 rad in bone.
The Systeme Internationale (SI) unit of absorbed dose is the gray (Gy), which has the units of Joules per kilogram. A gray is equal to 100 rad.
rem
REM stands for Roentgen Equivalent Man. The REM is a unit of absorbed dose and is equal to the rad multiplied by a weighting factor which varies according to the type of radiation. The weighting factor for x-rays is equal to 1. Therefore, for x-rays, one rem is equal to one rad.
The Systeme Internationale (SI) unit used in place of the rem is the sievert (Sv). A sievert is equal to 100 rem.
The unit used to measure the incident dose is joules per kilogram, and is known as “Gray” where 1 Gray (Gy) = 1 J/kg. The former unit used to measure the incident dose was the “Rad,” and using this unit, 1 Rad (rd) = 0.01 Gy, or 1 Gy = 100 rd.
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Many X-Ray machines have 3 controls (voltage, current and time)
KVP – KVP should be adjusted according to the thickness (density) of the body part. The thicker the body part, the more KVP needed.
The thinner the body part, the less KVP needed. {Quality}
MA – should be chosen from the technique chart {Quantity}
Time – should be chosen from the technique chart {Quantity}
Question/ Purpose:
What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.
What are the effects of X-Ray radiation on the germination, growth rate and overall development of radish seeds?
You can perform your experiment with any other types of seeds as well. The reason that we selected radish seeds, is that radish seeds germinate and grow very fast in a suitable growth environment.
Identify Variables:
When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.
Radiation dosage is an independent variable. The germination and growth rate are dependent variables.
Hypothesis:
Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis.
I believe X ray radiation will in some way affect the germination, growth rate and overall development of radishes.
Experiment Design:
Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”
Sample Abstract:
Living things are constantly being exposed to radiation. This exposure comes from natural sources as well as man-made sources. Radiation exposure can have both beneficial and harmful effects on living things. This project attempts to discover the effects of X ray radiation on the growth and development of radish seeds. I decided to use X rays because they are a very common form of man-made radiation. My project consisted of X-raying a total of 84 radish seeds at 7 different radiation dosage exposures. I also had a control group which received no X ray radiation. My overall results showed that there was virtually no difference in the germination rate between the experimental and control groups. However, the results also showed that the experimental group outperformed the control group in overall weight, length, and width of the averaged final plants. My background research on this topic explains the history, applications, and both healthy and harmful effects of X rays. My research also included a look at the history, care and growing of radishes.
Sample Procedure:
- 1. Take 84 radish seeds to an X-Ray facility and have them X rayed as follows:
- 12 seeds at 20 mrem (It takes 1000 mrem to equal one rem)
- 12 seeds at 125 mrem
- 12 seeds at 250 mrem
- 12 seeds at 500 mrem
- 12 seeds at .5 Rems
- 12 seeds at 40 Rems
- 12 seeds at 100 Rems
- 12 seeds no radiation (control)
mrs or mrems = millirems
If you have access to an X-Ray machine with kVp, mAs and time controls, you may set the kVp to 60, set the mAs to 10 and only change the exposure time. Suggested time settings are:
12 seeds No radiation (control)
12 seeds for 1/20 seconds
12 seeds for 1/10 seconds
12 seeds for 1/5 seconds
12 seeds for 1 seconds
12 seeds for 2 seconds
12 seeds for 4 seconds
12 seeds for 6 seconds
2. Gather materials needed for experiment (See material and equipment section)
3. Place soil in growing trays
4. Plant 84 experimental group seeds and label each group of seeds with their exposure
5. Plant 12 control group seeds and label the tray as control group.
6. Water each seed compartment .012 liters
7. Place experimental group and control group in sun
8. Check seeds each day
9. Water plants as needed (all plants must receive the same amount of water each time)
Depending on the type of seeds you select it will take about 3 to 5 weeks for your seeds to germinate and become young plants. (Warm, humid and sufficient light can reduce this time). That’s when you can make your final observation and recording.
10. Record observations in your log book
11. Record measurements of data in your log book
12. Take photographs of your results
13. Perform calculations (Average of length, width, weight in each group)
14. Evaluate results
15. Make conclusions
Materials and Equipment:
Two growing trays (Buy from a local nursery)
Log book
Sterilized packaged potting soil
Centimeter ruler
X-ray radiation lab
Camera
Radish seeds (156)
Computer
Label sticks
Calculator
Water and water container
Scale (Use a digital scale if available)
Notes: For X-Ray radiation you may use the services of X-Ray research labs, hospitals, dentists and X-Ray security systems.
If you decide to use Ultra Violet, UV lamps also known as black light are available at many hardware stores. They are available in the form of incandescent and fluorescent. For UV radiation consider using fluorescent UV lamps like the one shown in the right.
With UV radiation you can substitute the dosage by the exposure time and try exposure times of 3 hours, 6 hours, 12 hours, 24 hours and 48 hours.
Results of Experiment (Observation):
Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.
Following are some sample results:
CONTROL GROUP: 70 plants
| No x-Ray Exposure | Length (cm) | Width (cm) | Weight (grams) |
| Average Figure: | 1.543 | 1.287 | 2.550 |
EXPERIMENTAL GROUPS
Group #1: 12 plants
| Exposure 20 mrs | Length (cm) | Width (cm) | Weight (grams) |
| Average Figures: | 1.575 | 1.325 | 2.958 |
Group #2: 12 plants
| Exposure 125 mrs | Length (cm) | Width (cm) | Weight (grams) |
| Average Figures: | 1.755 | 1.573 | 3.818 |
Group #3: 12 plants
| Exposure 250 mrs | Length( cm) | Width (cm) | Weight (grams) |
| Average Figures: | 1.500 | 1.3666 | 3.0 |
Group #4: 12 plants
| Exposure 500 mrs | Length (cm) | Width (cm) | Weight (grams) |
| Average Figures: | 1.692 | 1.475 | 3.5 |
Group #5: 12 plants
| Exposure .5 Rems | Length (cm) | Width (cm) | Weight (grams) |
| Average Figures: | 1.733 | 1.375 | 3.5 |
Group #6: 12 plants
| Exposure 40 Rems | Length (cm) | Width (cm) | Weight (grams) |
| Average Figures: | 1.566 | 1.250 | 2.917 |
Group #7: 12 plants
| Exposure 100 Rems | Length (cm) | Width (cm) | Weight (grams) |
| Average Figures: | 1.875 | 1.540 | 4.417 |
Calculations:
For the seeds in each group, you will need to make measurements and finally calculate the average for each property (length, width, weight) in each group.
Summary of Results:
Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.
It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.
Conclusion:
Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.
Sample Conclusion:
My conclusions are that my hypothesis was partially correct. X rays did have an effect on the growth rate and overall development of radish seeds. However, X ray radiation had very little effect on the germination of the experimental and control group seeds. There was a 98% germination rate for both the experimental and control group seeds. My experiment showed that all the groups that were X rayed, performed better than the control group. The X rayed seeds produced plants that were on the average a little bit longer, wider and weighed more than the control group average. My exposure dosages ranged from 20 millirems to a high of 100 rem. Overall it appears that the higher the radiation exposure the better the overall development of the radish. The differences in length, width and weight of the plants is sometimes very, very subtle; however, my results seem to show that the increase in radiation dosage seems to be producing radishes which are overall longer, wider and weigh more than non radiated radish seeds. In evaluating my experimental process I tried to eliminate the possibility of mistakes being made. All my seeds came from the same package. I carefully separated the seeds which were to receive X ray radiation and labeled all packages as to their dosage. All seeds were planted in the same type of potting soil on the same day, and received the same amount of water, and were put out in the yard to receive the same amount of sun. All plants received the same amount of on going water and care throughout their growing period. All recorded data was entered into my log book on the same day for both the control and experimental group plants. I tried very hard to make sure all plants were treated in the same way all the time. If I were to do this experiment once again I would increase the dosage exposures and increase the sample sizes. My current sample sizes were 84 seeds for my experimental group and 72 seeds for my control group. I think that because the differences in the resulting plants is so subtle that a much larger sampling would produce more conclusive data. A variation of my project would not only be to increase dosages, but to also try other types of seeds such as carrots, lettuce, tomato and beans.
Related Questions & Answers:
What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.
Possible Errors:
If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.
If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.
Q. While I am experimenting this project with various rays (Xray, UV rays, Microwave, and Visible light) and trying to find out which electromagnetic waves is most harmful to plants growth? Now I need to have uniform exposure of the seeds to these waves so that results can be compared. What intensity is comparable between these waves?
How much of UV exposure to seeds is comparable to X ray, Visible light, and Microwave exposure in this experiment?
A. For the best results, the amount of energy per square feet must be the same for every types of radiation that you test; however, that requires enough data about the radiation sources and equipment to measure such radiation.
A simpler method is measuring the consumption of electricity or electrical energy and keep that a constant.
For example a 100-watt visible light bulb in one hour consumes 100 watt-hour energy. The same light bulb in 2 hours consumes 200 watt-hour energy or 0.2kwh.
A 50-watt UV light must work 4 hours to consume 200 watt-hour energy.
In this method we assume that the light sources are 100% efficient and no energy will be wasted in the form of heat. This method works well because in most light sources about 15% to 35% of energy will be wasted in the form of heat.
Q. Let us say if I am using an x-ray machine that has been set to kVp to 60, set the mAs to 10 and the exposure time is 1 second. How much watt hour it will consume so that I can set same amount of watt hour for visible and UV light.
A. This is how you calculate:
60 kVp is actually 60000 Volts.
10 mAs is actually 0.010 Amperes.
Power (watts) = Voltage (volts) x Current (amperes).
Power= 60000 x 0.010 = 600 watts
Energy (joules) = Voltage (volts) x Current (amperes) x Time (seconds).
Energy = 60000 volts x 0.010 Amperes x 1 seconds = 600 Joules
If you need the energy in kilowatt hours, you need to know that One joule is equivalent to 1 watt second. So 600 Joules = 600 x 3600 /1000 = 2160 kwh.
