377 results found

#### Power Output of a Solar Cell

Is the power output of a solar cell proportional to the sine angle between the incident light and the face of the power cell? The experiment that will be conducted is to see whether or not that there is any connection between the sine angle of light and the power output of a solar cell. Hypothesis The hypothesis for my experiment is that the power output of a solar cell is directly proportional to the sine of the angle between the incident light and the face of the solar cell. The sine of the angle of incidence and the face of the solar cells direction ? to the power out put OR Sin ? ? Pout where ? equals angle of incidence Prediction I predict that the results, when plotted on a graph, will show a strong positive correlation between the total power output of the solar cell that is proportional to the sine of the angle at which the light is shone at the solar cell. Variables Any Indirect light coming from another light source could affect the experiment. Wire temperature causing an increase in resistance Apparatus I will use two digital meters set on 200mA and 2mV range that will allow results to be measured to the nearest 1mA and 1mV respectively. Also a resistance box will be set on a resistance of 50? to try and keep the resistance level during the experiment. A standard lamp powered by mains electricity with a 60W bulb will be used as a light

• Word count: 1357
• Level: AS and A Level
• Subject: Science

#### Investigate the properties of a sensor.

SENSORS COURSEWORK PLAN: We were asked to investigate the properties of a sensor. The sensor I have chosen is a potentiometer. A potentiometer is a device which taps off a fraction of its input to provide a controlled output. It consists of a sliding contact which moves across wire coils to cause a change in resistance. Equal movements of the sliding contact give equal changes in output. We are actually using the potentiometer as a variable resistor so that instead of tapping of a proportion of the potential difference it taps off a part of the resistance. We are using a rotary potentiometer for our experiments. This means that the slider moves in a circular motion across the contacts. For us to be able to conduct tests we must be able to accurately measure how much we have moved the contacts so that we can compare it with the change in resistance. We have decided to measure the movement in degrees. This means we had to fix an arm to the moving contact of the potentiometer so that we could see the moving part of the potentiometer. Then we had to draw a circle on some card and mark of the degrees using a protractor. We then mounted the potentiometer on the card so that it was held firmly in place. This meant that now we could see how many degrees movement gives a certain out put. There are a number of things which we can investigate about the potentiometer: Resolution

• Word count: 2872
• Level: AS and A Level
• Subject: Science

#### Physics - Rotary Potentiometer

Can a Rotary Potentiometer be used as a conventional scale? Introduction I wanted to find out how a rotary potentiometer could be utilized to work as a weighing scale. The specific interest is the accuracy of this method and distinguish the advantages and disadvantages of using digital readings instead of our common everyday analogue spring gauge balance at the local supermarket. This investigation will require a potentiometer device being loaded with a series of masses which are linked to a voltmeter measuring the differences in voltage as more masses are added while a spring is used to hold the weight. The benefit of this system is that it can be calibrated in imperial and metric measurements as the results appear in Volts, whereas modern scales only provide 'grams' or 'kilograms' as opposed to pounds. Accuracy is vital in this task as there is a challenge to see how effective a potentiometer can be, with most spring scales can be accurate up to + or - 1g. Apparatus > 6V Battery pack (4 'D-sized' batteries), for ease of use and more energy efficient that a 12v mains power supply > Rotary potentiometer, attached to a DIY MDF wheel which rotates. It has a spring attachment hole at one end and a mechano shaft for attaching weights > Expendable Spring, an attachment unit to keep the rotating apparatus together, and the main unit holding weight of equipment > Digital

• Word count: 1142
• Level: AS and A Level
• Subject: Science

#### Measuring weight with a strain gauge.

Measuring weight with a strain gauge A strain gauge is a wire which is used to measure strain by the change in its resistance when it gets either longer and thinner or shorter and thicker. They are attached to a surface for which the strain is wanted, and need to be able to move as if they are part of the surface. Modern strain gauges are etched onto foil because its thin and flexible, and therefore able to move with the surface. Gauges are glued onto the test object with superglue so that they move as if they are a part of the object. Elastic modulus = stress/strain (When stress is a linear tensile or compressive stress, the elastic modulus is called Young's modulus). A tensile strain will be accompanied by a reduction (and compressive strain by an increase) in lateral dimensions. The ratio of the lateral strain to the longitudinal strain is called Poisson's ratio1. For most materials the value is between 0.25 and 0.4, and written as a positive number although the signs of the lateral and longitudinal strain are always opposite. The gauge factor of a strain gauge (G) = (?R/R)/(?l/l) where R = resistance and l = length. Since ?l/l is the strain (e) in the object which the gauge is attached to this can be written as ?R/R = eG, which means that the fractional change in resistance of the gauge is proportional to the strain in the object. To

• Word count: 1810
• Level: AS and A Level
• Subject: Science

#### The aim of our investigation is to investigate Ohms Law.

Siobhan Higgins G.C.S.E Science Coursework AT1 Aim- The aim of our investigation is to investigate Ohms Law. Introduction- In my investigation I am trying to prove that Ohm's law works. Ohm's law is used to find a value in a missing circuit. Georg Ohm, a German physicist proved that resistance is equal to voltage divided by current. Resistance is the difficulty in getting the current round the circuit. I will test the resistance of different lengths of nichrome wire. Prediction and Hypothesis I predict that the wider apart the crocodile clips are, the higher the resistance is. I know this as the longer the wire, the more free electrons there are, which means more collisions, which results in higher heat loss. Method- To make the test fair I need to repeat the test five times, and make sure I get accurate results. I will have to make sure that the crocodile clips are placed on the same spot for each try, I will do this by using a metre rule. To make this a safe test I will have to keep all wires and equipment neat. I will have to make sure that the desk is tidy. Between writing results I will have to switch the power pack off at the plug. I will have to make sure that I keep hair tied back, and make sure I don't touch the wire In the experiment I am going to measure the current, voltage and resistance, and the length of the wire, In the experiment I am

• Word count: 1041
• Level: AS and A Level
• Subject: Science

#### Aim To build and test a temperature sensor and analysing its suitability as a bath water thermometer.

Physics Sensing Coursework - Temperature sensor Aim To build and test a temperature sensor and analysing its suitability as a bath water thermometer. Introduction In making a temperature sensor the circuit and individual components need to be thought about. Also I need to find a way of measuring my sensor to calibrate its voltage output with the temperature it's measuring. First of all I require a component in my circuit which will change its electrical properties in the changing of temperature. This component is called a thermistor and there are two types; * The positive temperature coefficient thermistor or PTC thermistor has an increased resistance as temperature increases. These can be used as current limiters or in place of a fuse. Current through the device causes some resistive heating. If the current is too large the resistance increases due to heat increase and the current is reduced. * The negative temperature coefficient thermistor or NTC thermistor has a decreased resistance as temperature increases. Deciding on which of these to use in my circuit isn't a problem because both will change with temperature change just one has its resistance changed opposite to the other in temperature change. However there are some thermistors which are not suitable for this type of temperature measurement. Many PTC thermistors are of switching type, which means that their

• Word count: 642
• Level: AS and A Level
• Subject: Science

#### Black Box Electronics Coursework

Investigating in Sc. 4(Physics) Problem: Three different types of electrical components are hidden in "Black Boxes", my task is to identify each component by investigating its properties. The components are labeled A, B, C, and consist of a fixed resistor, a light emitting diode and a filament bulb. Which is which? Planing In each graph the current is reversed in the negative part of it. Ohmic Conductor: If a substance gives you a straight graph, like this one, this then will be an ohmic conductor. Ohm's Law: George Ohm discovered that the current flowing through a metal wire will be doubled (that doesn't apply on a lamp because it changes the temperature) Diode: You can notice that in the reversed direction there weren't any current, but when it is normal it increases. Filament Lamp: It is not an ohmic because the graph isn't straight and that doesn't obey ohm's law. As more current flows, the metal filament gets hotter and the resistance increases. (Graph gets flatter). I will do a test for each component once. For each test I will change the resistor 11 times, 5 times at normal resistor and 6 at reverse. Equipment: * Voltmeter * Ammeter * Power Pack * Switch * Variable Resistor For My Safety: . I mustn't keep the power pack appliances running for a long time, because that will heat up the wires. 2. I mustn't plug in too many plugs in a socket

• Word count: 713
• Level: AS and A Level
• Subject: Science

#### Find the relationship between the current through a resistor and the voltage across it.

MYP Physics Practical - Current and Voltage Aim: To find the relationship between the current through a resistor and the voltage across it. Apparatus: Power pack, Leads, Ammeter, Voltmeter, Resistor (Nichrome Wire) Method: Assemble the circuit shown above. Vary the emf of the power pack from 0 to 12 Volts. Measure the current on the ammeter and voltage on the voltmeter for each value of emf. Data Collection: Thin Nichrome Wire EMF Current (Amperes) Voltage (Volts) 0 0 0 2 0.15 .75 3 0.27 2.5 4 0.38 3.25 5 0.5 4.25 6 0.6 5 8 0.85 7 0 9 2 .2 0.5 Medium Nichrome Wire EMF Current (Amperes) Voltage (Volts) 0 0 0 2 0.38 .6 3 0.5 2.4 4 0.8 3.2 5 4 6 .2 5 8 .6 6.5 0 2 8.5 2 2.35 0 Thick Nichrome Wire EMF Current (Amperes) Voltage (Volts) 0 0 0 2 .3 .25 3 2 .75 4 2.65 2.5 5 3.4 3 6 4.1 3.6 8 - - 0 - - 2 - - Data Processing: Conclusion: From the three graphs above it can be seen in all of them that there is a firm relationship between the two factors, one being voltage and second one being current. Therefore I have accomplished my aim, as I have found what is the relationship between the current through a resistor and the voltage across it. The relationship as can be seen from the graph is positive, and thus directly proportional. This can be seen from the graph itself, because firstly,

• Word count: 1153
• Level: AS and A Level
• Subject: Science

#### Circuits - To prove the equation: Resistance (&#8486;) = Potential Difference Current.

Circuits Experiment Aim To see prove the equation Resistance (?) = Potential Difference ÷ Current. This is to be done by setting up a series of circuits containing a voltmeter, an ammeter, cells for the different potential differences, and light bulbs for causing the resistance. Hypothesis I predict that as I increase the amount of bulbs in the circuit the resistance will increase, this is because the electricity must flow through a small filament which has a high resistance already; bulbs have high resistance filaments because they give off more light. I also think that when I increase the number of cells in the circuit, the potential difference will also increase; this is because the cells each have a potential difference on 1.5 volts. Apparatus * 3 Power Cells * Voltmeter * Ammeter * Power leads * Bulbs with a known resistance Method . Set-up a circuit in accordance to the diagram below 2. Record the amps and potential difference values in a results table, then increase the number of cells in the circuit by a value of one each time, making sure to record the amps and potential difference after each change. 3. After adding a total of three cells to the circuit and recording the results, remove the extra cells from the circuit so that it is the same as in the diagram 4. Then increase the number of bulbs in the circuit by a value of one, and record the results

• Word count: 639
• Level: AS and A Level
• Subject: Science

#### Investigate how the charge on a capacitor is related to the potential difference applied across it by charging the capacitor at a constant rate.

Charging a capacitor at a constant rate Objective: ~ To investigate how the charge on a capacitor is related to the potential difference applied across it by charging the capacitor at a constant rate. Apparatus: ~ Capacitor (electrolytic type) 500F ~ Microammeter 100A ~ Potentiometer 100k ~ Clip component holder ~ Stop-watch ~ CRO ~ Connecting leads Description of design: Theory: From definition, the capacitance C of a capacitor is found from, where Q is the charge stored on the capacitor and V is the potential; difference across it. Then, . If a capacitor is charged up at a constant rate, i.e.=I, where I is a constant. Then= is also a constant. Hence, the potential difference across the capacitor increases linearly with time. Data Analysis: The result of this experiment is shown as below: p.d. across capacitor V V 2V 3V 4V 5V st attempt Time t 5.92s 1.73s 7.67s 23.67s 29.42s 2nd attempt Time t 5.90s 1.30s 6.87s 22.71s 28.59s 3rd attempt Time t 5.19s 0.75s 6.94s 22.85s 28.72s Discussion: When the capacitor is being charged up, the microammeter reading decrease with time, and the CRO trace reading increase constantly. Since the current should be kept in a steady rate in order to make a fair test, so we have to adjust the amount of current for the sake of keeping the current in uniform. Also, form the result shown above, we will

• Word count: 479
• Level: AS and A Level
• Subject: Science