Investigating the effect of resistance on a capacitor circuit.
Investigating the effect of resistance on a capacitor circuit Method: We will set up the following circuit. We will measure the capacitor pd. (Vc) with the cell connected. Then we will remove the cell and connect point A to point B, at the same moment starting a stopwatch. We will record the length of time (t) for the Vc to decay to 3.75 Volts. We intend to repeat this procedure using different resistors. Resistance (k?) Time (s) 33 33 68 72 00 97 50 53 330 320 680 584 Conclusion: From the graph we can clearly see that the time taken for the capacitor to discharge is directly proportional to the resistance. This is because the graph shows a definite straight line going through or near most of the points. This means that the higher resistor you use the longer it will take for the capacitor to discharge. The experiment has therefore proved the prediction correct i.e. the resistance should be directly proportionate to the time taken for the capacitor to de-charge. This can be explained by the following: Capacitors store electrical charge. When current is passing through the circuit the capacitor charges up as the current can't jump between the gap of the two plates but charge is held there because of the force of the opposite poles. This means that more and more electricity is stored until it reaches its full capacity. But when the circuit is broken the
The birth of electricity comes from what we call an atom or atoms and its interaction with other atoms.
The birth of electricity comes from what we call an atom or atoms and its interaction with other atoms. The contents of an atom are in three parts, a proton, a neutron, and an electron. The proton is known to be with a positive electrical charge. The neutron is known to be neutral or without an electrical charge. The third particle is called an electron which is known to be with a negative charge. The center of the atom (nucleus) would contain both the proton, and the neutron. The electrons have a negative charge. The Protons have a positive charge. The neutron has no charge, or is neutral. Like heat is attracted to cold, negatively charged electrons are attracted to the positively charged proton. The positively charged proton, and the neutron which has no charge, are found to be stationary in the center of the atom, called the nucleus. Many negatively charged electrons can revolve randomly around the proton and neutron, at the same time, and in different orbits. The negatively charged electron (energy) would be attracted to the positively charged proton due to the attraction created by the opposite forces. Some types of structures are called non-conductive (some plastics and ceramics), and some are called conductive (metals). An atom with the least amount of free electrons in its outer orbit are called insulators (non-conductive) An atom with many free electrons in its
The aim of my investigation is to determine the specific heat capacity of aluminium.
The Specific Heat Capacity of Aluminium Aim: The aim of my investigation is to determine the specific heat capacity of aluminium. Theory: Specific heat capacity is the amount of energy required to raise the temperature of 1kg of mass by 1degree Celsius.(1) In order to calculate the specific heat capacity heat capacity (c) of aluminium I can use the equation, H=mc T (2) Therefore c= H m T I can measure the mass of the aluminium, (m), and the change in temperature of the block, ( T), however the energy change, ( H), is hard to measure. Another equation I can use to calculate H is the equation E=ItV (3). I can measure the energy supply using an electrical heater and recording the current the time and the voltage. Using the first law of thermodynamics or conservation of energy (E=(H. Therefore ItV=mc(T. Using this knowledge I can design the basic circuit required to record the necessary measurements. The aluminium block has two holes one containing a heat filament and one containing a thermometer. In order to try and measure the energy from the heating filament entering the block I need to prevent as much heat being lost into the environment as possible. Heat can escape in three ways, by convection, conduction and radiation. 'Convection involves the bulk motion of a fluid (liquid or gas) and is usually caused by hot fluid
Investigation of a light dependant resistor.
Investigation of a light dependant resistor Light dependant resistors or LDRs are resistors which alter their resistivity according to a particular light level. I am going to find out how these work and use them in a context so I can use them to locate a light source. To do this I must firstly find out how light effects the LDRs and then use this data to try and create something in order to detect a light source and locate it. Results Distance light is away from LDR Voltage reading (supply-12v) 5cm 1.5 0cm 0.9 5cm 8.7 20cm 6.4 25cm 3.7 30cm .9 As you can see from these results as the light intensity increases, the resistance decreases. I need to find the range of light levels the LDR can detect and distinguish how sensitive it actually is. The maximum resistance it is possible to get from the LDR is 550k?. This is when there is maximum light shining on the LDR. The minimum resistance that is possible is 0.90k?. This is when the LDR is submitted to complete darkness. To Use these LDRs effectively, I need to use two of them connected in series, and as the light moves across form one to another the resistance should decrease in the LDR that has more light shining on it and increase on the one in relative darkness compared to another one. The voltage placed across the resistors and the current flowing through must be the same because it is
Find how changing the amount of voltage (potential difference) coming out of the power pack will affect the current while it is flowing through a filament bulb of 24W.
Physics Coursework Filament Bulbs Aim: My aim is to find how changing the amount of voltage (potential difference) coming out of the power pack will affect the current while it is flowing through a filament bulb of 24W. Diagram: The power pack supplies a direct current (DC) to the circuit. The voltmeter is in parallel to measure the potential difference across the bulb and the ammeter is in series to measure the current flowing through the circuit. Method: . Get all the equipment and set it up as shown in the diagram. 2. Set power pack so that the voltage shows 10V on the voltmeter. 3. Record the number of amps that are flowing through the circuit by reading the ammeter. 4. Repeat steps 2 + 3 for 20, 30, 40 and 50 Volts. 5. Repeat the steps 2 through 4 two more times to get three sets of results. Make an average and this leaves you with a set of good, accurate results. Fair Test: To make my experiment a fair test I will have to make sure I keep many things the same. First of all, the power pack; I will have to use the same power pack for each test as they will all give out slightly varied voltages to each other. I will also have to use the voltmeter to judge how much voltage is coming out as the power pack dial is more than likely inaccurate. In addition, I must use the same light bulb as each bulb will have a slightly different resistance, therefore giving us a
The aim of this investigation is to find out if the length of an electrical resistor (graphite putty) affects its resistance.
Physics Coursework: Electrical Resistance Aim: The aim of this investigation is to find out if the length of an electrical resistor (graphite putty) affects its resistance. Prediction: An electrical current is the movement of electrons through a substance. Resistance occurs when the electrons travelling through the substance collide with the atoms of the substance. This collision slows down the flow of electrons causing resistance. Resistance is the measurement of how hard it is for electrons to move through a substance. The resistance of a substance is measured in Ohms (?), which can be shown in the formula: Voltage Resistance = --------------- (Equation 1) Current All substances have a resistance, the more resistance a substance has the less current gets through. The resistance of a substance can be altered by factors which include: * Temperature Heat energy gives the atoms of the resistor more energy causing them to vibrate. This results in more collisions between the passing electrons and the atoms of the resistor. Therefore, resistance of a resistor is increased if the temperature is increased. * Cross-sectional area The larger the cross-sectional area is, the less likely the electrons will collide with the atoms of the substance they are flowing through. Therefore, resistance of a resistor is decreased if the cross-sectional area is increased. *
Objective To investigate the relationship between the charge on a capacitor and the p.d. across the capacitor by charging at a constant rate.
School: Ng Wah Catholic Secondary school Class: F.6B Name: Tang Pak Lap ( 19 ) Subject: AL Physics Date: 7th May 2007 Mark: Topic C8 Charging a capacitor at a constant rate (TAS) Objective To investigate the relationship between the charge on a capacitor and the p.d. across the capacitor by charging at a constant rate. Apparatus > Capacitor, 500 ?F > Microammter, 100 ?? > Potentiometer100 k? > Clip component holder > Hand-held stop watch > CRO > Connecting leads Procedure . Connect the following circuit. Set the CRO to d.c. and the sensitivity to 1 Vcm-1 2. Set the time base of the CRO to a high sweep rate so that a steady horizontal trace is displayed. Shift the trace to the bottom of the screen. 3. Short out the capacitor by connecting a connecting wire across it (XY). Adjust the 100 k? potentiometer to a suitable value for a steady current to flow (e.g. 80µA). 4. Remove the shorting wire and the capacitor will charge up. 5. Repeat the above procedure and record the time for the capacitor to charge up at a constant rate. The potentiometer must be adjusted to keep a constant current flowing in the circuit. 6. Measure the times for the CRO trace to move up by 1cm, 2cm, 3cm. The height is equivalent to the voltage across the capacitor. Tabulate the results. Results P.d. across capacitor V/V 2 3 4 5 Time t/s 6.15 2.06 8.87 25.28
Internal Resistance of a cell
Topic: Internal Resistance of a cell Aim: To measure the internal resistance and emf (the potential differences across a voltage Source when no current is flowing) and to observe the combination of cells Hypothesis: The emf of the old cell is less than the emf of the new cell but the internal resistance of the old cell is much greater than the new cell. Introduction: Resistance in electricity, property of an electric circuit or part of a circuit that transforms electric energy into heat energy in opposing electric current. Resistance involves collisions of the current-carrying charged particles with fixed particles that make up the structure of the conductors. Resistance is often considered as localized in such devices as lamps, heaters, and resistors, in which it predominates, although it is characteristic of every part of a circuit, including connecting wires and electric transmission lines. (Britannica.2006) The dissipation of electric energy in the form of heat, even though small, affects the amount of electromotive force, or driving voltage, required to produce a given current through the circuit. In fact, the electromotive force V (measured in volts) across a circuit divided by the current I (amperes) through that circuit defines quantitatively the amount of electrical resistance R. Precisely, R = V/I. Thus, if a 12-volt battery steadily drives a 2-ampere
Investigating the Voltage - Current characteristics of a Resistor and a Filament Lamp
Investigating the Voltage:Current characteristics of a Resistor and a Filament Lamp Mr Lawrence's Prediction Both a resistor and a filament lamp obey Ohm's law. Ohm's Law As voltage doubles, so does the current for a conductor at a constant temperature. Diagram for Experiments Resistor Filament Lamp Results Table's Resistor Power Pack Reading Voltage (V) Current (A) Resistance 2 0.65 0.06 0.83 4 2.36 0.27 8.74 6 3.92 0.45 8.71 8 5.94 0.70 8.49 0 7.58 0.90 8.42 2 9.35 .09 8.58 Power Pack reading Voltage (V) Average Voltage* Current (A) Average Current** 0.01 0.01 0.01 0 0.01 0.01 0.01 0.01 2 0.34 0.33 0.34 0.3 0.2 0.2 0.2 0.20 3 0.6 0.59 0.54 0.6 0.27 0.25 0.25 0.26 4 2.07 2.12 2.10 2.1 0.41 0.41 0.14 0.41 5 3.08 3.07 3.06 3.1 0.49 0.49 0.49 0.49 6 4.04 4.04 4.04 4.0 0.56 0.56 0.56 0.56 7 4.91 4.93 4.94 4.9 0.61 0.61 0.62 0.61 8 5.98 6.02 6.02 6.0 0.68 0.68 0.68 0.68 9 6.90 6.88 6.93 6.9 0.73 0.73 0.73 0.73 0 7.81 7.82 7.82 7.8 0.78 0.78 0.78 0.78 1 8.69 8.70 8.71 8.7 0.83 0.83 0.83 0.83 2 9.61 9.57 9.61 9.6 0.87 0.87 0.87 0.87 *Rounded to 1d.p **Rounded to 2d.p Filament Lamp Filament Lamp Resistance Table Voltage (V) Current (A) Resistance 0.0 0.01 0 0.3 0.20 .5 0.6 0.26 2.3 2.1 0.41 5.1 3.1 0.49 6.3
A2 Viscosity investigation
Investigation to determine the viscosity of golden syrup and the effect temperature has on this. I will determine the viscosity of syrup at the following temperatures (10°C, 20°C and 30°C). I will be plotting my results on separate graphs to determine the viscosity and then plot them on the same graph to help determine the effect of temperature. Apparatus: Golden syrup Measuring cylinder 5 ball bearings of varying sizes Weighing scales Stop clock Micrometer Nitre rule Magnet (to get ball bearings out of syrup) Thermometer Water bath For the density of steel I will use the accepted value of 7850kgm-3. To work out the density of golden syrup I will measure the weight of 50cm3 and use the formula ?= where m is mass and v is volume. I will do this for each temperature I temperature will affect the density. Method: . Using the micrometer measure the diameter of the ball bearing. 2. Weigh the ball bearing using the weighing scales and record the results in a table. 3. Measure 6cm on the measuring cylinder and draw two lines draw the line all the way around the cylinder as this will make it easier to ensure you are at eye level. (ensure the first line is at least 3cm from the top of where the syrup is filled to as it needs time to reach terminal velocity) 4. Place the ball bearing into the syrup then get to eye level of the first line to ensure maximum accuracy
