# Measuring the Depth of Water Using Sound Waves

Aim The aim of my investigation was to create a sensor which could measure the depth of water in a tank. Plan The way I proposed to measure the depth of water was using sound waves which would be emitted and fired into the tank of water. The sound wave should then be reflected of the bottom of the tank and picked up by a microphone. The microphone would be linked to an oscilloscope and the sound emitter would be linked to the oscilloscope. I would then measure the phase difference between the waves. Then by changing the depth of water in the tank, I would see what relationship would be produced between the phase difference and water depth and test how well the sensor worked. Below is a circuit diagram which shows how I wanted to lay out my investigation and the components involved: The safety conditions I took into consideration when I did my investigation were where:

# Investigating Osmosis

Introduction Knowing that osmosis (a diffusion of water) will occur across a semi-permeable membrane whenever there is a difference between the water concentrations on the two sides of the membrane, and knowing that when this happens to cells they will either become turgid if water flows into them, or plasmolysed if water flows out of them, and thus change their volume, we want to test the hypothesis that: If the concentration of a solution into which a cylinder of potato is placed is greater than a certain level the cylinder will contract, and if the concentration is less than that level it will expand. We have studied turgidity and plasmolysis in a textbook (Key Science-Biology, pages 143-144) and in a preliminary experiment, where we first added 2% sucrose solution to rhubarb epidermal cells, and saw them become plasmolysed, and then added water, and saw them become turgid. However, we did not use different solution concentrations, and did not measure the amount of contraction or expansion that took place. From our results in the main experiment, we should be able to work out not only the amount of contraction or expansion caused by each strength of solution, but also the concentration of the sap inside the cells. Apparatus ? For the experiment we will require: ? Either cylinders of potato with a diameter of 6.5mm and a height of 5mm, or a potato, a borer with a diameter of 6.5mm and a scalpel. (To allow us to make our own). ? Solutions of varying strengths (of sucrose and NaCl), or a solution of a known strength and distilled water. (To allow us to make our own). ? Pins (To ensure that cylinders remain separate while in the solutions.) ? Test-tubes ? Callipers (To measure cylinder height and diameter.) Diagram Method We take a cylinder of potato, with a diameter of 6.5mm, from the potato, and cut it into separate cylinders each with a height of 5mm. We then thread at least three of the cylinders, to make the experiment fair (in case one of the cylinders is abnormal or damaged), on to a pin, keeping them apart from each other. We then make up solutions of either sucrose or sodium chloride, either by % strength or by molarity, and place 4 millilitres of each strength into a separate test-tube. We used a range of % sucrose solutions, going from distilled water (0%) to 2% (which we knew from earlier experiments would plasmolyse the cells), and a range of sodium chloride solutions from distilled water (0) to 0.4 molar (which would again be enough to plasmolyse the cells)

# Osmosis in a Potato

Aim The aim of this experiment is to find out what concentration solution of sucrose a piece of potato can be placed in, so that no water is lost or gained by the potato cells. Prediction The solution can not be 100% sucrose concentration, because the potato will become plasmolysed or flaccid due to the lack of water. The solution can not be 100% concentration water because this will cause the potato to become turgid. I predict that the concentration will be close to 50%, more specifically, in between a concentration of 60% sucrose and 40% sucrose. In the preliminary experiments that were carried out, the potato, which was placed in the 50% concentration sucrose solution, gained water. Scientific Knowledge Osmosis is the movement of water molecules from a weaker solution, to a stronger solution, down the concentration gradient. This occurs through a partially permeable membrane. This continues until dynamic equilibrium is reached. Equilibrium is the state of both of the solutions having an equal concentration. After equilibrium is reached, water particles keep moving, however, they move very quickly, so there is no net movement.

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# The Mosque and Its Importance to Muslims

Introduction A mosque is symbolically very important to Muslims, and is a humble way for man to recreate pure divine presence on earth. Mosques are not built according to divine patterns ? they are divinely guided. Nor are there very clear rules to what a mosque should look like, except on some few points. Mandatory elements are a structure that clearly indicates the direction of Mecca (this direction is called Qibla). The indication is in most mosques a mihrab, a niche in the wall. A mosque must have a roofed area in front of the mihrab. There can be no doors in the wall where the mihrab is placed ? for the other walls, there can be as many doors as the builders want.

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# The Effect of Intensity of Light on the Rate of Photosynthesis

The aim of my experiment was to determine whether or not the intensity of light would affect the rate of photosynthesis in a plant. To do this, I placed a piece of Canadian pondweed in varying light intensities, and observed the amount of oxygen being given off. I used Canadian pondweed because of its unusual quality of giving off bubbles of gas from a cut end, when placed in water. Introduction Photosynthesis occurs only in the presence of light, and takes place in the chloroplasts of green plant cells. Photosynthesis can be defined as the production of simple sugars from carbon dioxide and water causing the release of sugar and oxygen. The chemical equation for photosynthesis can be expressed as: (light) 6CO2 + 6H2O À C6H12O6 + 6O2 (in the presence of chlorophyll) The fact that all plants need light in order to photosynthesise has been proven many times in experiments, and so it is possible to say that without light, the plant would die.

# Investigating How Light Intensity Affects the Rate of Photosynthesis

The aim of this activity is to observe and justify how the amount of light intensity exposed to a plant affects the amount of photosynthesis the plant performs. I am trying to investigate the affect of light intensity on photosynthesis on a plant. My hypothesis is that as the light intensity on the plant increases, the photosynthesis the plant performs will also rise proportionally. However I also hypothesize that when a certain level of light intensity is reached, the rate of increase will itself decrease. At this point temperature may become a limiting factor, which there is no control of. I think this will happen because my scientific research shows that the formula for photosynthesis is:- 6CO2 + 6H2O +light = C6H12O6 + 6O2 Carbon Dioxide + Water + light = Glucose + Oxygen Light is needed along with Chlorophyll to create a chemical reaction so that this conversion can take place. Without light, this cannot happen, and chlorophyll, found in chloroplasts can not convert water and Carbon Dioxide.

# Investigating The Efficiency of Sun Block Cream

Aim of Investigation: The aim of this investigation is to discover how efficient sun block cream is and whether the claims by the company agree with my results. Why I chose this experiment: I chose to do this experiment because it seemed more interesting to me. Rather than just testing a sensor I thought it would be more interesting and rewardable to use a sensor to test something else. Also sunburn can be very serious and can cause illness therefore it is important to have efficient sun cream to prevent sunburn. What I am doing: I am going to take a range of factors of the same brand of sun cream and measure the level of UV radiation, which is allowed through each. It would also be good to test different brands as well however I could not obtain enough different brands of sun cream to carry out an experiment like this. What is UV radiation?

# An Investigation of the Water Potential in a Root Vegetable

Water potential is represented by the Greek letter Psi (Î¨) and is measured in Megapascals (MPa). Water potential is the measurement of the ability of water molecules to diffuse from a region of high water potential to a region of low water potential down a concentration gradient. The water molecules move through a semi-permeable membrane and can move in either direction and do so according to the Î¨ on each side. For example if a cell with a high water potential was placed in a solution with a low water potential the water molecules would leave the cell via the membrane, and would continue to do so until the solution has the same Î¨ as the cell, this is termed equilibrium. If a cell with a low water potential was placed in a solution with a high water potential the water molecules would be absorbed by the cell via the membrane until the equilibrium has been met. After the equilibrium has been reached there will be no net movement of water molecules. Osmosis is the net movement of water molecules from a region of high concentration to a region of low concentration.

# Investigating the Factors that Affect the Acceleration of a Ball Bearing Down a Ramp

Investigating the Factors that Affect the Acceleration of a Ball Bearing Down a Ramp I intend to investigate what factors affect the acceleration of a ball
bearing down a ramp. I will measure how long the ball bearing takes to
roll down a ramp, and my other variable will be to measure the final
velocity of the ball bearing rolling down the ramp. Using this
information I will then be able to work out the acceleration of the
ball bearing down the ramp. I will be able to work out the velocity of
the ball bearing, and therefore be able to work out the acceleration
using a different formula above.

# Evaluating Fox Hunting

Introduction I am going to do my piece of original writing coursework on something I feel strongly about. It is an issue that many other people also feel strongly and which provokes a lot of feelings and emotions from both sides. The thing I am going to be doing my piece of original writing coursework on is Fox Hunting. [image] Fox Hunting is when mounted huntsmen and women chase a fox with dogs or hounds (as they are called by hunters) which are trained to catch the fox and then rip it to pieces. It was not until the decline of falconry (training and using falcons for hunting: the breeding, training, and use of falcons or other hawks to hunt small prey and return from flight at a falconer?s direction), in the 17th century that the first fox hunts, consisting of organized groups of hunters and their servants and hounds, were established in England. Today the officials of the hunt and the members generally wear coats of bright scarlet, called pinks. However today many people feel that fox hunting is a cruel and unnecessary practise.