Physics Spring Coursework
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Varying the current in an electrical circuit affects the strength of an electromagnet.
As the current is increased in a wire, the strength of the magnetic field becomes greater and therefore more effective. An A.C current would demagnetise the core while a D.C. current would magnetise a core. This is because the D.C. current is direct and therefore all the electrons are arranged in the same order creating a magnetic field. When the current is A.C, the electrons are free to move where they want so there is no magnetic field. When an electromagnet has a current induced in it, it becomes magnetised and the greater the current induced the greater the strength. This is because the microscopic domains within the nail receive a greater current and so the strength and actions of these domains are increased. In addition, if the solenoid receives greater current then the field it generates will be stronger. . On the power pack, which I will be, using there is an option to change the voltage, which could be altered to change current with the aid of an ammeter. The main implication of the domains is that there is already a high degree of magnetization in ferromagnetic materials within individual domains, but that in the absence of external magnetic fields those domains are randomly oriented. A modest applied magnetic field can cause a larger degree of alignment of the magnetic moments with the external field, giving a large multiplication of the applied field. Aim The
Centripetal Force Experiment. Measure the centripetal force and compare it with the theorectical value Fc=mrω2
AL Physics TAS 1 Centripetal Force (2008/11/12) . Objective To measure the centripetal force and compare it with the theorectical value Fc=mr?2 2. Theory Consider an rubber bung moving with constant angular speed in a circular path, where ? is angle between string and vertical, T is tension in the string, m is mass of rubber bung, g is acceleration due to gravity, L is length of string, r is the radius of circular path, and ? is the angular speed of bung. Theorectically, Mg=T= m?2L, where M is mass of weights used. 3. Method Refer to the figure in the worksheet. 3.1 Electronic balance was used to measure the mass of bung, metal weights and hanger. 3.2 Meter ruler was used to measure the length of string. 3.3 Stop watch was used to record the time for 20 revolutions. 3.4 It was not easy to keep L unchanged when whirling the bung, so we had to practise for a while before taking the data. 4. Data Analysis Mass of rubber bung (m) is 0.0192 ± 5×10-5 kg. L / m (±5×10-4) M / kg (±5×10-5) Mg / N Time for 20 revolutions (t)/ s (±0.005) ? / rad s-1 m?2L / N st Trial 2nd Trial Mean 0.750 0.1000 0.981 6.05 6.25 6.15 7.78 0.872 0.800 0.1200 .18 3.17 3.22 3.20 9.52 .39 0.800 0.1400 .37 2.03 2.66 2.35 0.1 .59 0.750 0.1600 .57 2.92 3.06 2.99 9.67 .35 0.750 0.1800 .77 1.75 1.72 1.74 0.7 .65 Table 1 5. Errors and
A careful quantitative study of the relationship between the velocity of a trolley down a slope and the angle of the slope.
A careful quantitative study of the relationship between the velocity of a trolley down a slope and the angle of the slope. The velocity of trolley as it rolls down a slope will vary depending on the size of the angle of the slope relative to the ground. This theory comes from the general formula for gravitational potential energy: Where GPE is gravitational potential energy, m is the mass of the object, g is the acceleration due to gravity, and h is the height at which the object is from the ground. The gravitational potential energy increases as the height of the object increases and is proportional to the increase in velocity. The gravitational potential energy lost is equal to the kinetic energy gained. This means that, as the trolley's displacement from the ground decreases, i.e. it moves down the slope, h becomes less significant and the GPE decreases, thus increasing the KE. This increase in KE means that the trolley is moving at an increased speed, thus the velocity increases as it travels down the slope. The GPE decreases constantly as the body moves down the slope; the velocity is also increasing constantly, which means that it is accelerating. The acceleration for each of the different heights will be greater as the gradient increases, as the rate of increase of velocity is proportional to the gradient of the slope. Experiment Equipment: * one pair of light
Electromagnet Investigation
What is a electromagnet Planning An electromagnet consists of an iron core with a wire wrapped round it and current flowing through the wire A conductor carrying a current (I) induces a magnetic field. This due to the fact that moving charges induces magnetism and the current consists of moving (e ) What are they used for? Electromagnets are widely used in technology and are the essential components of relays and circuit breakers. Electromagnets are also used in electromagnetic clutches and brakes. In some streetcars, electromagnetic brakes grip directly onto the rails. Very large electromagnets having cores several meters in diameter are used in cyclotrons, and high-power electromagnets are used to lift iron parts or scrap. This was Found From Encarta This has helped me so now I see a point in the experiment. Also people who use the high-powered electromagnet would need to know how to get it high powered. Keeping in mind current costs money so they may choose to use another way with a lower current. About Electromagnets (Core) The iron core in an electromagnet is full of magnetic domains, which are randomly pointing anywhere therefore cancelling them out. When an electric current is passed through the coil; this induces a strong magnetic field. The iron core is then placed in this field; causing the domains to point in one direction (The direction of the
Investigation on Transformers.
Investigation on Transformers Background Information on Transformers "Every transformer has three parts: (Physics, David Sang Chapter 21 pg 342) * Primary Coil - incoming voltage V1 is connected across the coil * Secondary Coil - this provides the voltage V2 to the external circuit * Iron core- this links the two coils" The turns ratio tells us the factor by which the voltage changes: * A step-up transformers increases the voltage - there are more turns on the secondary than on the primary * A step-down transformer reduces the voltage - there are fewer turns on the secondary than on the primary. There is a "transformer equation", relating Vp and Vs to the number of turns on each coil, Np and Ns can be derived. The equation is Vp/Vs = Np/Ns. This tells us that since the magnetic field in each coil is the same, it follows that the e.m.f in each coil is proportional to the number of turns in the coil. (Physics, David Sang Chapter 21 pg 342) How do they work? "Transformers only work with alternating current (a.c.). The alternating current in the primary coil produces a varying magnetic field in the core. The core transports this alternating field around to the secondary coil. This induces a varying current in the secondary coil." (Physics, David Sang Chapter 21 pg 342) Variables * Input Voltage- This is the only variable being changed in this experiment. The
EMF Investigation - electricity and magnetic fields.
EMF Investigation Planning Aim and hypotheses According to Fleming's Rule, electricity is generated when movement occurs in the magnetic field. Alternatively, switching direction of the magnetic field also works. Alternating current is a good way of alternating the field direction. The electricity generated, of in the other words, the electromotive force, is measured in volts. By varying different parts of the apparatus, the EMF output could also vary. The aim of this investigation is to establish a connection between the factors and the output. Possible factors that could be altered in a general apparatus are: * Frequency of field alternation * No of coil of wire in the magnetic field * Strength of magnetic field, varied by * - size of electromagnet * - current used to establish and maintain the magnetism of the electromagnet * - no of coil used to magnetize the electromagnet * Moving the wire in the magnetic field A preliminary experiment, with the same apparatus used, is done earlier on and some useful information was acquired from it. As it was mentioned that alter the direction of the field generates electricity, and it was found out in the preliminary experiment that the more frequent that the field is altered, the quicker would electricity be generated, so by looking at different frequency, perhaps a pattern indicating the relation. In an experiment
I am going to investigate what affects the strength of an electromagnet.
Electromagnetic Coursework Area P I am going to investigate what affects the strength of an electromagnet. Things that I believe are likely to affect the strength are the strength of the current; the number of coils; the presence of a soft iron core; the type of wire; the resistance of the wire and the temperature. I will investigate how the number of coils affects the strength. In the experiment the only changing variable will be the number of coils. Everything else will stay the same-everything else being the temperature; the wire length; the wire thickness; the resistance; the type of wire and the presence of a soft iron core. To control the temperature I will need to keep switching the current on and off, so to do this I will add a variable resistor to the circuit that will do this for me. The resistance will be controlled if the temperature is controlled, since the two are connected and inversely proportional. I will measure the electromagnet's strength by setting up the circuit shown above. The nail will point vertically upwards, to avoid getting interference from gravity. I will slowly bring a spring balance into contact with the nail. Since the tip of the spring balance is iron, a magnetic metal, it will be attracted to one end of the electromagnet and therefore allow me to measure the number of Newtons in force before the spring balance
Sliding & Friction Lab Report
Kimberly Cuthbert-Holmes March 16, 2008 St. Thomas Aquinas Mrs. Guzas Science - Lab Report I. Introduction In this lab, Shannon and I were investigating the affect of different materials on the force of friction. Our question was how do different sliding surfaces affect the friction of objects. The physical property of different surfaces affects the amount of friction that results when they encounter each other. The greater the friction force between the two surfaces, the greater the force needed to cause motion. With this being said, I think the smoother the surface, the less friction the surfaces will have when they are in contact, causing the object to move quicker. This experiment can be applied to a real-life situation. The friction between the tires of your automobile and the road determines your speed. Depending on the weather conditions or the material the road is made of, can affect your speed. When it is raining, your car tends to go faster because you have a layer of water lubricant under your tires. Your car can move faster because less force is needed for the car to move. On the hand, when you are driving on a gravel road, you need greater force to cause motion because the surface is not smooth as asphalt paved road, which is flat. There are three different types of variables in this experiment. The independent variables in this
Determining the force constant
A6: Determining the force constant Objective To find out the force constant of a given spring using Hooke's Law. Result hanger and slotted mass (m)/g 20 periods / s one period (T) /s T2 / s2 t1 t2 mean time 39.96 2.07 2.20 2.14 0.61 0.37 50.09 3.82 3.76 3.79 0.69 0.48 60.23 5.30 5.25 5.28 0.76 0.58 70.33 6.52 6.50 6.51 0.83 0.68 80.24 7.60 7.51 7.56 0.88 0.77 90.17 8.30 8.50 8.40 0.92 0.85 00.23 9.57 9.69 9.63 0.98 0.96 Calculation Slope of the best-fit-line: = 9.65 The spring constant (k): K = = 4.089 Discussion Assumptions for the experiment In this experiment, we assume that the spring is weight-less. Also, we assumed that the effect of air resistance acting on the mass and the spring is negligible . Difficulties encountered When conducting the experiment, we initially used a spring which cannot be extended significantly. As a result, we cannot conduct the experiment efficiently as we couldn't see the tiny change in period. Later, we replaced it with another spring with greater extension so we could conduct the experiment more smoothly. We encountered difficulties in counting the number of oscillation because initially the mass was moving up-and-down very fast. Luckily, we came to a solution to count the number of oscillations accurately by counting the number out loud. If the mass of the hanger and slotted