1057 results found

#### Measuring the e.m.f. And Internal Resistance of a Cell

Measuring the e.m.f. And Internal Resistance of a Cell Planning I wish to find out the electromotive force (e.m.f.) and Internal Resistance of a direct current battery cell. Circuit Diagram . Set up apparatus as shown. 2. Use ammeter to adjust variable resistor to vary of currents. 3. Read voltmeter value and record. 4. Disconnect circuit and take e.m.f reading from voltmeter across cell. 5. Repeat for another 9 resistor settings. Use variable resistor and ammeter to adjust the set up to get a range of 0.1 to 1.0A. 6. Repeat entire experiment to get more accurate average. Safety Aspects . Do not have circuit connected up for too long, this will run the battery down and may cause it to heat up and maybe explode. 2. Wear safety goggles and lab-coats during experiment. 3. Follow standard laboratory safety procedures. Apparatus 0 - 1.0A analogue ammeter 2 digital voltmeters 1 variable resistor 1 cell 8 connecting wires. Safety goggles and lab-coat Paper and pen Arranging Evidence Results Current (Amps) Potential Difference (V) 2 3 Average 0.1 .46 .47 .46 .46 0.2 .42 .42 .41 .42 0.3 .36 .39 .36 .37 0.4 .33 .33 .33 .33 0.5 .27 .29 .28 .28 0.6 .24 .23 .23 .23 0.7 .18 .19 .20 .19 0.8 .13 .15 .14 .14 0.9 .10 .09 .11 .10 .0 .04 .03 .06 .04 Using these results I will be able to draw a graph to find the e.m.f.

• Word count: 1572
• Level: AS and A Level
• Subject: Science

#### I hope to find out how resistance of a wire is affected.

INVESTIGATION TO SHOW THE EFFECTS OF THE RESISTANCE OF A WIRE Aim: - I hope to find out how resistance of a wire is affected. Prediction: - I predict that as the length of the wire increases the resistance will also increase. Scientific Knowledge: - A wire is a bundle of metal strips coated in plastic. The plastic can vary in colour and connect to different terminals These are: - * Black = negative terminal * Red = positive terminal * Blue = neutral terminal * Green and yellow = earth terminal * Brown = live terminal The material varies because it has free electrons, which are able to flow through the wire. The number of the electrons depends on the amount of electrons in the outer energy shell of the atoms, so if there are more or larger atoms then there must be more electrons available. If the material has a high number of atoms there will be a high number of electrons causing a lower resistance because of the increase in the number of electrons. Also if the atoms in the material are closely packed then the electrons will have more frequent collisions and the resistance will increase. Resistance is measured in Ohm's (?). Ohm's Law The law actually says that the resistance of a metal conductor is the same whatever the current - unless it's getting hotter. However most people think of these equations when the law gets mentioned: V = IR V is Voltage in Volts, I

• Word count: 581
• Level: AS and A Level
• Subject: Science

#### We are aiming to investigate the effect of force upon a spring. We will also investigate Hooke's law, to see what happens using two springs in parallel and series, and how this effects the spring constant.

Investigation - Hooke's Law Aim: We are aiming to investigate the effect of force upon a spring. We will also investigate Hooke's law, to see what happens using two springs in parallel and series, and how this effects the spring constant. Background: I know that Hooke's law states that spring extension is proportional to stretching force, so long as the spring was not permanently stretched. In this investigation we will explore this statement. Trial Run: We did a trial run before starting the main experiment, and we found that we had to carefully put the weights on to the hanger, as the spring quickly stretches and could break. We also had to make sure we took the measurements at the same place each time, i.e. at the bottom of the spring or the bottom of the hanger, as this could affect our results. We also found that the spring could take 10N without deforming. Prediction: From the scientific knowledge above I can make a prediction about this experiment. I predict that the extension of the spring will be proportional to the force applied to it, and that it will return to its original size when the force is released. When we have two springs in parallel I predict the force will have an effect on them as a whole, and they won't stretch as much as the single spring, so the spring constant will increase. When two springs are in series I predict the force will have

• Word count: 1535
• Level: AS and A Level
• Subject: Science

#### Mass on a spring - and investigation into resonance

An Experiment to Investigate a Mass on a spring as an Example of Resonance Method We set up the apparatus as shown below. We also included a meter rule to the left of the spring so that we could see the size of the oscillations. We set the signal generator to produce a sine wave output and set both the frequency and amplitude to a minimum. We switched on the signal generator and set the amplitude to its middle setting. We pulled down gently on the load and allowed the spring to oscillate. We slowly increased the frequency, monitoring the amplitude of the oscillations of the load by reading from the meter rule placed next to the apparatus. We noted when the amplitude appeared to be at its largest and took this frequency to be the resonant frequency. We repeated the experiment using different masses and decided to repeat each experiment 3 times for comparison. Measurements Before commencing the experiment, we considered what precautions we could take to ensure accuracy. We placed a meter rule by the apparatus to give us the best possible chance of observing the largest amplitude correctly. We weighed the entire spring system (Weights, hanger and spring as all of these items were involved in the actual oscillation that we were measuring) each time we changed the mass of the system to ensure and accurate reading for mass. We felt that just adding weights and assuming

• Word count: 1264
• Level: AS and A Level
• Subject: Science

#### The purpose of this laboratory investigation is to verify the validity of the Lens Equation which states that 1/di + 1/do = 1/f.

Lab: Applying the Lens Equation Daniela Perdomo Lab Partner: Stephanie Landers Date: 21 November 2002 Place: Graded School - São Paulo, Brazil Time: 8:10 h - 9:35 h Purpose/Introduction: The purpose of this laboratory investigation is to verify the validity of the Lens Equation which states that 1/di + 1/do = 1/f, where di is the distance from the image to the lens, do is the distance from the object to the lens, and f is the focal length. Hypothesis: The laboratory investigators hypothesized that the data obtained in the procedure of this experiment would be consistent with the Lens Equation. Though different methods of obtaining focal lengths (f) will be used throughout the lab, the obtained f's should still be equal. Materials: * 2 double convex lenses * 1 candle * 1 box of matches * 1 meter stick * 1 lens holder * 1 cardholder * 1 candleholder * 1 blank card Diagram: Procedure: The first lens used in this investigation was a double convex lens, which indicates that light should converge when shone through it. The first way used to discover its focal length was by using sunlight. A cardholder, with a card in it, was placed on the meter stick and the lens holder, with the convex lens in it, placed in front of it (i.e. closer to where the sunlight was coming from). The lab investigators then moved the lens until the image on the card was focused enough

• Word count: 1671
• Level: AS and A Level
• Subject: Science

#### Physics of Rollercoasters

Rollercoaster Report Aim: To investigate changes in gravitational potential and kinetic energy and how these changes relate to the velocity of an object. Hypothesis: The velocity of an object will be greater when going down the hills of the rollercoaster and lower when going up the hills. The kinetic energy at the highest point on a hill will be lower than the kinetic energy at the lowest point. Equipment: * One ball bearing (28.57g) * Cardboard (used to construct rollercoaster) * Thick blue paper * Metre ruler * Tape * Pair of scissors * Steak knife * String * Camera (digital * Electric scales * Pencil Method: Creating the rollercoaster . Two pieces of cardboard were chosen. 2. The "hills" of the rollercoaster were drawn onto the two pieces (which would make the two sides of the rollercoaster) using a pencil. 3. The two pieces were cut using a knife and taped onto a cardboard base. 4. A piece of thick blue paper was measured and cut to be the ramp of the rollercoaster. 5. Tabs were cut into the paper to make it easier to attach it to the rollercoaster. 6. Ramp was stuck between the two pieces of cardboard using tape onto the rollercoaster. The experiment . Ball bearing was weighed using electric scales. 2. Height of the rollercoaster at 3 high and 3 low points were measured using string. 3. Total distance of the

• Word count: 1214
• Level: AS and A Level
• Subject: Science

#### 'What effects the strength of an electromagnet?'

'What effects the strength of an electromagnet?' Introduction: An electric current flowing through a wire produces a magnetic field. Coiling the wire produces a stronger magnetic field. Coiling it around a soft iron core increases the strength effect; raising the current or the number of coils increases it further. I am going to investigate the raising of the current and how it affects an electromagnet. I think the electromagnet will produce a stronger magnetic filed and pick up more iron fillings. Aim: To investigate factors which affect the strength of the electromagnet and make the strongest electromagnet possible. Apparatus: · Iron Rod · Leads · Power Pack · Crocodile Clips · Insulated Wire · Iron Filings · Voltmeter · Plastic Beakers · Electronic Balance Hypothesis: I expect the strongest electromagnet to have a 'soft' iron core; the number of coils being (45) the current varies, the strongest amps being (7.00A) and have the coils evenly spread across the iron rod. The 'soft' iron core means it changes easily between being magnetised and de-magnetised, it is perfect for electromagnets, which need to be turned on and off. From a previous experiment, using an electromagnet, I found out that the iron rod picked up many filings when turned on and dropped them all when switched off but the steel rod picked few filings up when switched on, yet held

• Word count: 824
• Level: AS and A Level
• Subject: Science

#### A Personal Experience.

• Word count: 1527
• Level: AS and A Level
• Subject: Science

#### Measuring the acceleration due to gravity in the lab.

Measuring the acceleration due to gravity in the lab Aim Our aim was to find the acceleration due to gravity in the laboratory. Method The distance between the ceiling and the floor (h) was measured. A rubber was then dropped from the ceiling and the time taken for it to hit the ground was recorded. Results Attempt Time Taken (sec) 0.47 2 0.45 3 0.71 4 0.55 5 0.5 6 0.71 7 0.4 8 0.46 9 0.58 0 0.56 Average Time = Sum of all times Number of Times = (0.47+0.45+0.71+0.55+0.5+0.71+0.4+0.46+0.58+0.56) 10 = 5.85 10 = 0.59 sec (to 2 dp) H = height of the drop T = time taken Acceleration due to gravity = 2H T2 =2(2.59) 0.592 = 5.18 0.3481 = 14.88 m/s2 (to 2 dp) Evaluation The results circled in the table are anomalous. There was a wide range of results, from 0.4 to 0.71. This spread of results indicates that the data may be inaccurate. Although the experiment was repeated nine times, different results were found at nearly every attempt. This could be due to the timing methods used. A stop clock held by a person was used to measure the time the rubber took to hit the ground. As a human's reaction times are not perfect, the button could have been pressed long after the rubber had touched the ground. Also, the timekeeper could have pressed the button too early; at the time he expected the rubber to fall in order to try and get a more

• Word count: 589
• Level: AS and A Level
• Subject: Science

#### Does An Electrolyte Behave Like A Resistor?

Does An Electrolyte Behave Like A Resistor? Aim To see the relationship between the Current and the Voltage for a liquid. Circuit Diagram Anode Cathode Copper Sulphate (CuSO ) solution Method This experiment was done as a demonstration. The results were obtained by adjusting the variable resistor to give a range of readings from the ammeter and voltmeter. These results are shown in results table and the graph. Results Voltage Current (A) Average Current (V) st Test 2nd Test 3rd Test (A) 0 0 0 0 0 .0 0.14 0.12 0.17 0.14 2.0 0.30 0.26 0.36 0.31 3.0 0.46 0.42 0.52 0.47 4.0 0.67 0.60 0.70 0.65 5.0 0.71 0.83 0.86 0.80 Conclusion The graph is showing a straight line through the origin. This means that as the voltage increases, the current also increases uniformly. A graph of Voltage and Current for a resistor was the same, when I did the experiment. This means that the liquid behaves like a resistor. Which was what we were trying to find out. In a liquid, a current is the movement of ions. In Copper Sulphate (CuSO ) solution the sulphate ions are negative and move to the anode, the copper ions are positive and move to the cathode. The anode is the positive plate and the cathode is the negative plate. If you increase the voltage then the plates become more charged and the ions move around faster, so the

• Word count: 486
• Level: AS and A Level
• Subject: Science