Investigation of the response of a microphone / loudspeaker over a range of frequencies
Investigation of the response of a microphone/loudspeaker over a range of frequencies Aim & Hypothesis To become proficient with using a signal generator and a Cathode Ray Oscilloscope (CRO.) Also, to investigate how the amplitude of a signal from a microphone varies as the frequency of a fixed amplitude signal applied to the loudspeaker varies, (between 100Hz and 1000Hz.) Safety RISK ASSESSMENT - LEVEL ONE This experiment does not carry many hazards. Bags and coats will be moved out of the way to ensure that no one will trip over them. The only other potential danger is as a result of using mains operated equipment. I will not be using the equipment near any water, taps etc. I will do a visual check on the equipment before use (not fraying or lose wires, etc.) Variables Independent Variable: Frequency (Hz) Dependent Variable: Amplitude (mV) I will be using the signal generator to alter the frequency being produced - therefore this will be the independent variable. This will alter the amplitude of the wave being shown on the CRO so this is the independent variable. I have used the same equipment throughout the experiment in order to ensure a fair test. Diagram Method The apparatus was set up as shown on the previous page. Firstly I did three 'checks' to ensure that (to check if they are properly calibrated.): * The amplitude of the signal remains constant *
An experiment to investigate the rate of reaction between
An experiment to investigate the rate of reaction between marble chips and hydrochloric acid The aim of this experiment is to find the factors that affect the rate of reaction between calcium carbonate and hydrochloric acid. The equation for this reaction is shown below. Calcium Carbonate + Hydrochloric Acid --> Calcium Chloride + Water + Carbon Dioxide The variables that I believe are most likely to have an effect in my experiment are: . Temperature 2. Concentration (of hydrochloric acid) 3. Surface area (of marble chips) 4. A catalyst However instead of investigating all four variables, I have chosen to investigate how different concentrations of hydrochloric acid affect the rate of reaction between marble chips and hydrochloric acid. My prediction for this experiment is that as the concentration of hydrochloric acid increases, the rate of reaction will also increase in direct proportion. My reasons behind the above prediction are that so a reaction can take place, the particles of the substances reacting have to collide. If they collide with enough energy then they will have enough energy in order for them to react. If the concentration of hydrochloric acid is increased it will, in turn, increase the number of particles in a given volume, in contact with the marble chips. This will lead to more collision, so the rate of reaction will increase also. Doubling the
To determine the concentration of limewater
To determine the concentration of limewater The aim of my experiment is to find the concentration of limewater solution provided. To do this I am provided with the following chemicals. Limewater: 250cm (1g dm ) Hydrochloric acid at concentration of 2 mol dm As you can see the hydrochloric acid is too concentrated for titration (i.e. one drop could change the colour of the solution.) therefore this acid will need to be diluted. Background knowledge: Limewater can be made by dissolved slacked lime in water to get a solution of calcium hydroxide (Ca (OH) 2 ) Quicklime + water --------> slaked lime CaO (s) + H2O (l) --------> CaCl2 (aq) + 2H2O (l) In this reaction it shows the calcium oxide reacts with water to produce calcium hydroxide. After adding more water to calcium hydroxide, it produces the saturated aqueous solution known as limewater. My experiment will be based on this neutralisation reaction between the limewater and hydrochloric acid. Ca(OH) 2 (aq) + HCl (aq) --------> CaCl2 (aq) + 2H2O (l) (back ground knowledge of limewater provided by AS chemistry 1 page...) Diluting hydrochloric acid: My first task for this experiment is to dilute the hydrochloric acid. To do this I first needed to work out how many moles I wanted for hydrochloric acid. For this part of my calculation I choose to use text book Calculations for chemistry to help me.
How does the power dissipated by a light bulb vary with voltage?
How does the power dissipated by a light bulb vary with voltage? Plan Introduction For my experiment, I am going to investigate how the power dissipated by a light bulb varies with voltage. To find this out, I will need to do an experiment to test this out and repeat it another two times. Meaning of terms Current - Current is the flow of electric charge. An ammeter measures current in a circuit. Voltage - Voltage is the potential difference between two points in a circuit is the electrical energy gained or lost by 1 coulomb of charge. A voltmeter measures voltage between two points in a circuit. Resistance - If a component has resistance, it changes some of the electrical energy passing through it into another form of energy. A rheostat can increase or decrease its own resistance so in that way I can control the amount of voltage across the light bulb whilst doing the experiment. Prediction I think that as the voltage across a light bulb increases, the power dissipated by the light bulb also increases but at a greater rate. This is because as the voltage increases, the current also increases. This is because if the current is the amount of electrons flowing through a circuit at any point in a circuit and if the voltage increases then the current must increase as the electrons flowing through that point are flowing faster. Therefore, as the voltage increases, the
Osmosis in Potatoes Lab. At which concentration of sucrose in water (% mass by sucrose) will the potato core be isotonic, meaning that there is no movement of water in or out of the potato core?
Osmosis in Potatoes Date of Experiment: Feb. 4, 2009- Feb. 6, 2009 Research Question: At which concentration of sucrose in water (% mass by sucrose) will the potato core be isotonic, meaning that there is no movement of water in or out of the potato core? Hypothesis: If the percent mass by sucrose of the solution is in between 10 and 30 percent, then the solution would be isotonic, meaning that no osmosis occurs between the potato and the solution. I assume this because the percent change before and during 10 percent indicates water moving into the potato (hypotonic), and the percent change during and after 30 percent mass by sucrose indicates that water is moving out of the potato (hypertonic). Variables: > Independent: o Percent of mass by Sucrose in each solution > Dependent: o Percent change in mass of potato cores > Control: o Length of time each core stayed in solution o Size of each potato core o Amount of solution in each test tube o Temperature of solution and surrounding area o Potato from which the cores come from Materials: o Potato Electronic Scale o Cork Borer 6 Test Tubes o Tweezers Beaker o Water with different amounts of Sucrose (0%-50% by mass) Procedure: . Fill each test tube with __ mL of only one solution of water and sucrose (0%- 50% by mass). 2. Label each test tube with the solution it is holding (% of mass by sucrose in
Biology Revision notes - Human Biology
Blood Pressure * Each time your heart contracts, it pumps blood into out arteries. * The blood needs to be under pressure so that it reaches all the parts of the body. A pulse - this is the recoiling of the arteries. Arteries are elasticised so that when blood is pumped, they expand and then contract. * The fitter you are, the lower your heart rate is because your heart is more efficient. * Pressure is created due to the blood pressing against the arteries and this is known as blood pressure. Blood pressure appears as a fraction and is measures in mmHg: Systolic: the heart contracts and pumps - The highest pressure on the arteries. Diastolic: the heart is relaxes and doesn't pump - The lowest pressure on the arteries. (mmHg - millimetres/mercury) Blood pressure is affected by: * Weight - being overweight increases the risk of high blood pressure * Exercise - strengthens heart muscles and keeps the heart fit * Diet - avoid salty and fatty foods * Temperature * Alcohol * Stress * Smoking - narrows blood vessels * Inheritance * Age - blood pressure increases with age * Underlying diseases High Blood Pressure Can cause: * An artery to burst * A stroke * A heart attack * Death High blood pressure means that the blood is pushing too hard against the artery walls. This damages the artery lining and allows fat and calcium to build up and form a plaque.
n this essay I will analysing what makes us happy and be going into vast depths as to what factors affect happiness and how certain chemicals, neurotransmitters and endorphins in the brain affects this procedure.What makes us happy
What Makes Us Happy By John Smith In this essay I will analysing what makes us happy and be going into vast depths as to what factors affect happiness and how certain chemicals, neurotransmitters and endorphins in the brain affects this procedure. Firstly I will be assessing the key question; what is happiness? We already know happiness has many forms, but what we will be going into, is what defines happiness and how do we find this out? In order to be happy, scientists have put the ideas of many generations of people together and have come with a theory that makes us happy. [1]To begin with we must have a goal, whereby we have a point of destination we consider worthy for our effort, this goal can be really small or really big. Secondly, we also need to live our life with enthusiasm, optimism and honesty. Only after reaching all these areas, can we become happy people. For reaching the superior more advanced forms of happiness, such as achieving satisfaction and contentment, we require taking paths leading to a meaningful life; a life where through having goals, we will find fulfilment. Generally the rule is that; the smaller the goal, the shorter the time of happiness, for example; buying a new car or a new home can give us a quick feeling of enjoyment but at the same time can quickly wear off, compared with these next factors. Health, family and friends,
What affects osmosis
Elena Uteva Investigating the factors that affect osmosis in a model potato cell Introduction In the following investigation, I shall explore and come to a conclusion on the effect of varying the concentration of the surrounding sucrose solution on a model potato cell. Osmosis is defined as the passage of water molecules through a selectively permeable membrane from a region of high water concentration to a region of low water concentration until a state of equilibrium is reached. The selectively permeable membrane is permeable to the solvent and not to the solute and therefore results in a pressure gradient across the membrane. My hypothesis regarding this investigation is that an increase in the concentration of the sucrose solution will decrease the mass of the potato chip. This is because a higher solute concentration will result in lower water concentration, since by increasing the solute concentration there would be more solute molecules in a given volume and hence a lower amount of water molecules. Therefore by placing the model potato cell into a hypertonic solution, the water concentration will be higher in the cell in relation to the solution (www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/ Osmosis.htm) and consequently will result in the water molecules diffusing out of the cell and the cell loosing mass. Conversely, by decreasing the
Graphs illustrating variants of y = sin x.
Part 1 Graph 1 Graph 1 is showing y = sin x. Now lets look at the graphs of y = 2sin x ; y = ? sin x ; y = 5sin x y =2sin x Graph 2 y = 1/3sin x Graph 3 y = 5sin x Graph 4 If we compare graphs 2, 3 and 4 we can see that the number in front of sin (this number is called A) changes the vertical compression of the wave. When A<1 then the graph vertically compresses or amplitude becomes lower (graph 3) and when A>1 then graph expands vertically or amplitude becomes higher (graphs 2 and 4). If the number is 2, then the wave doubles vertically and when the number is 1/2 it compress by half. The comparison is of course made with the graph of sin x. Now let us see what happens when we make the equation negative by putting a minus sign in front of sin. By doing this we are taking A<0. Graph 5 Graph 5 shows us that the wave flips around when A is negative. So we can conclude that when A<0 the wave will always be upside down From investigating graphs of y = Asin x, we can conclude that when the A is less than 1 then the wave compresses vertically and when A is greater than 1 the wave expands vertically. If A is less than 0, then the whole wave flips upside down. To conclude we can say that A will equal to the number on the y-axis because
Plan: The effect of the end product, phosphate, on the enzyme phosphatase
The effect of the end product, phosphate, on the enzyme phosphatase . Plan Phosphatase enzymes release phosphates from a variety of substrates for synthesis of nucleotides, phospholipids, etc. They are found in both plant and animal tissues and can be classified as acid or alkaline depending on their optimum pH. In this experiment an acid phosphatase from potato was used. Hypothesis Since phosphate is a product of phosphatase activity, it may act as an end product inhibitor of the phosphatase enzyme, therefore slowing down the enzyme-catalyzed reaction. Background knowledge Enzymes are biological catalysts which speed up the metabolic reaction inside the cells. Enzymes are proteins and therefore can function because of their specific 3D shape. The active site is part of the molecule which allows the substrate to enter and form enzyme-substrate complex. If the shape of the active site changed, the substrate will not fit in, therefore the enzyme cannot function properly. The activity of enzyme is not only affected by temperature, pH, but also by enzyme inhibitors. These are the substances which can reduce the activity of enzymes. There are two types of enzyme inhibitors which refer to competitive and non-competitive inhibitor. Competitive inhibitor is a molecule which has a similar shape to the substrate, competing with the substrate for the active site of the enzyme and
