Submitted BY: ASHUTOSH KUMAR CLASS: XII-A . Examination held in Physics lab at Jai Hind Public School EXAMINER Date :-_________ . Date :-20-01-2015 Submitted for Central Board of Secondary Education. Guided By :Class :XII – A Year :2014.2015 Roll No :School :JAI HIND PUBLIC SCHOOL Certified to be the bonafide work is done by Master Ashutosh Kumar of class XII-A in the Physics Lab during the year 2014-2015. I extend my hearty thanks to Mr. S. which has sustained my efforts at all the stages of this project work… I can’t forgot to offer my sincere thanks to lab assistant and also to my classmates who helped me to carry out this project work successful and for their valuable advice and support ._____________.who guided me to the successful completion of this project.ACKNOWLEDGEMENT I wish to express my deep gratitude and sincere thanks to the Principal. constant encouragement . I take this opportunity to express my deep sense of gratitude for her invaluable guidance. which I received from them time to time…. Sharma. . I sincerely appreciate this magnanimity by taking me into his fold for which I shall remain indebted to him.L. immense motivation . Jai Hind Public School for his encouragement and for all the facilities that he provided for this project work. Mr. Physics teacher. 1-- Introduction 2-.Procedure 6-.Objective 3-- Material required 4-.Theory 5-.Observation 7-- Conclusion 8-- Bibliography…… . the results will resemble an exponential curve.OBJECTIVE THE OBJECTIVE OF THIS EXPERIMENT IS TO DETERMINE THE EFFECT OF TEMPERATURE ON THE STRENGTH OF A MAGNET. Graphically. Our dependent variable is magnetism. with magnetic force decreasing as temperature increases. the stronger the magnetic force. this will be calculated using the amount of paperclips that the magnet is able to collect at each measured temperature . HYPOTHESIS It is believed that the colder the magnet. Our independent variable is temperature. MATERIAL REQUIRED • • • • • • • • • • Safety glasses 3-4 permanent bar magnets Tongs for magnet Ice Water Insulating container Three strong bowls Small pot Burner for heating water or oven Paper clips(1000) . Even the earth itself is a magnet.Magnets are frequently used in daily life. Slower movement leads to more fixed directions in terms of the domains. referred to as permanent. Additionally. The higher the heat. magnets are used in manufacturing. These domains function as all atoms do. heating to high temperature). and as such the movement of the particles. Magnets are filled with magnetic lines of force . hold their magnetism without an external electric current. on the other hand. As the temperature of the magnet approaches this point. In contrast. security. are those that lose their magnetic charge properties over time. thus the temperature affects the movement. paramagnetic objects are those that can become magnetic only when in the presence of an external magnetic field. The motion of negatively charged electrons in the magnet determines not only the polarity. repeatedly jarring the metal. In the 1800’s. the greater the energy. Soft magnets. the alignment of each domain decreases. . the magnetism decreases until the Curie point is reached. entertainment. The north pole is positive. but also the strength of the magnet (Cold magnet). These lines originate at the north pole of the magnet and continue to the south pole. A magnet is any object that produces a magnetic field . at which time the material becomes paramagnetic. The temperature at which this demagnetization occurs is called the “Curie point”.e. Magnetic lines of force do not intersect one another. For example. A magnet of this nature can be created by exposing a piece of metal containing iron to a number of situations (i. A magnetic field is the space surrounding a magnet in which magnetic force is exerted. Pier4re Curie discovered that there exists a temperature at which objects that were previously permanently magnetic lose this characteristic . Magnetism is created by the alignment of small domains within a specific set of metal. As such. and they play a crucial role in the functioning of computers. cold temperature slows the movement (magnetic Field Strength and Low Temperatures). Some magnets. THEORY A magnet is a material or object that produces a magnetic field. "Hard" materials have high coercivity. and magnetically "hard" materials. These include iron. Permanent magnets are made from "hard" ferromagnetic materials such as alnico and ferrite that are subjected to special processing in a powerful magnetic field during manufacture. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials. The overall strength of a magnet is measured by its magnetic moment or. A permanent magnet is an object made from a material that is magnetized and creates its own persistent magnetic field. Although ferromagnetic (and ferrimagnetic) materials are the only ones attracted to a magnet strongly enough to be commonly considered magnetic. some alloys of rare earth metals. and this threshold depends on coercivity of the respective material. the total magnetic flux it produces. and attracts or repels other magnets. which do. nickel. An everyday example is a refrigerator magnet used to hold notes on a refrigerator door. such as iron. which can be magnetized but do not tend to stay magnetized. cobalt. The local strength of magnetism in a material is measured by its magnetization. are called ferromagnetic (or ferrimagnetic). to align their internal microcrystalline structure. all other substances respond weakly to a magnetic field. To demagnetize a saturated magnet. making them very hard to demagnetize. alternatively. and some naturally occurring minerals such as lodestone. by one of several other types of magnetism. . Materials that can be magnetized. a certain magnetic field must be applied. which are also the ones that are strongly attracted to a magnet. Ferromagnetic materials can be divided into magnetically "soft" materials like annealed iron. whereas "soft" materials have low coercivity. 3. Place magnet in bowl filled with paperclips. Set freezer to 5-Celsius degrees higher than previous temperature. Remove magnet and attached paperclips and place on scale. (Note: freezer accuracy is dubious. 9. Record temperature of magnet and grams attracted. Place paperclips in bowl. Remove paperclips and place back in bowl. Subtract the weight of the magnet from the weight of the magnet and the paperclips combined. 12. Use temperature read by freezer thermometer) 13. 11. Record temperature read by freezer thermometer. 2. 4. 8. Weigh magnet and record. 5. Repeat steps 4-12 until freezer and magnet have reached zero degrees Celsius. Place magnet and freezer thermometer in freezer set to lowest temperature possible. 7. Wait approximately 20 minutes for the magnet to reach the temperature of the freezer. . .PROCEDURE Cold Process 1. 10. 6. Situate scale near bowl. 5. 3.Hot Process 1. Wait approximately 20 minutes for the magnet to reach the temperature of the oven. Remove magnet and attached paperclips and place on scale. Place magnet in bowl filled with paperclips. 10. 2. Record temperature of magnet and grams attracted. Repeat steps 6-11 until magnet reaches room temperature. . 8. Remove paperclips and place back in bowl. Situate scale near bowl. Subtract the weight of the magnet from the weight of the magnet and the paperclips combined. Place magnet in oven set to highest temperature possible. 4. Allow magnet to rest for 5 minutes undisturbed. 7. Weigh magnet and record. 6. 11. 9. Place paperclips in the bowl. 12. OBSERVATION MAGNETS UNDER EXTREME HEAT Time after removal from oven (minutes) Weight attracted (in grams) 0 200 5 200 10 240 20 210 25 230 30 220 35 206 40 204 45 200 50 185 . 6 220 -1.7 200 0 225 .MAGNETS UNDER EXTREME COLD Temperature (degree celsius) Weight attracted (in grams) -21.7 260 -6.4 275 -18.7 245 -4.3 275 -19.3 270 -13.1 265 -15. . but the average is about 600 to 800 degrees Celsius. this balance is destabilized. This lack of cohesion weakens the magnetic force and eventually demagnetizes it entirely. Paramagnetism A type of magnetism that occurs only in the presence of an external magnetic field. At this temperature. As the atoms are sped up. the atoms slow down so the magnetic domains are aligned and. magnetic properties are then affected. and the total magnetization is zero. the ferromagnetic material becomes paramagnetic. Ferromagnetism The way in which specific materials form permanent magnets or interact strongly with magnets. . In contrast. too much heat can completely ruin a magnet. when a magnet is exposed to extreme cold. Different magnetic materials have different Curie Temperatures. the percentage of magnetic domains spinning in the same direction decreases. Even if you cool the magnet. While cold strengthens magnets. in turn. but they are not magnetized when the external field is removed. however.conclusion Magnetic materials should maintain a balance between temperature and magnetic domains (the atoms’ inclination to spin in a certain direction). Excessive heat causes atoms to move more rapidly. Curie Temperature Named for the French physicist Pierre Curie. In other words. When exposed to extreme temperatures. once it has become demagnetized. strengthened. it will not become magnetized again. Most everyday magnets are a product of ferromagnetism. the spins aren’t aligned. heat can result in the loss of magnetic properties. the Curie Temperature is the temperature at which no magnetic domain can exist because the atoms are too frantic to maintain aligned spins. Aluminum and oxygen are two examples of materials that are paramagnetic at room temperature. disturbing the magnetic domains. They are attracted to magnetic fields. That's because the atoms spin in random directions. howmagnetswork.technopedia.com www.com NCERT Physics book www.BIBLIOGRAPHY www.com .wikipedia.icbse.com www.sciencebuddies.com www.