Measuring Definition and 962 Threads

Homework Statement A small flat circular disc of diameter 2mm and mass 5mg is lowered vertically to rest at the centre of a flat tray of width 10mm in the x direction and 50mm in the y direction. What is the minimum uncertainty in measuring the velocity of the particle in the x direction...

I'm conducting a lab in which I change the distance of a lamp from a solar panel and use a multimeter to measure the resulting voltage. What type of relationship am I supposed to find? My results seem to indicate either a relationship with either a quadratic equation as its model or an inverse...

Light is conceived as a self-propagating perturbation of the EM field. This may sound like a silly question, but has this perturbation actually been measured/observed? Or is it accepted as the most parsimonious option that matches the evidence we have? My guess is that it is impossible to...

Homework Statement An astronaut arrives at a new planet, and gets out his simple device to determine the gravitational acceleration there. Prior to this arrival, he noted that the radius of the planet was 7040 km. If his 0.400-m-long pendulum has a period of 1.0 s, what is the mass of the...

Homework Statement A double-slit interference pattern is observed on a screen 1.0m behind two slits placed on 0.3mm apart. Ten bright fringes span a distance of 1.65cm. What is the wavelength of the light? Homework Equations Since we're looking at bright fringes: (m+1/2)\lambda =...

HI, How do i feed the current information into micro-controllers ADC input to calculate the total power? Please help. I am using atmel tiny45 and its a boost converter output current i want to measure for output power. Thanks.

Hi! I am looking for a way to measure the voltage on a Kelvin Water Dropper that I've built. This is quite problematic since the charge is small and the voltage is high. The only way to do it, as it seems to me, is to measure by influence. Any suggestions?

Pendulum measuring the restorative force HELP! Homework Statement A pendulum with length L is suspended at an angle theta. At the bottom of the pendulum, a string is attached to force meter. The string attached to the force meter is perpendicular to the pendulum string. In terms of F and...

Hi I'm a little confused when it comes to measuring the momentum in a infinite or finite square well. Is this even possible? One of the postulates of quantum mechanics states that measuring an observable will leave it as an eigenstate of that observables corresponding operator just after...

If you had an extremely sensitive scale (use your imagination) and shone a beam of light upon it, could you measure the force that the photons were exerting on the scale? would there even be a force?

Homework Statement It has recently become possible to "weigh" DNA molecules by measuring the influence of their mass on a nano-oscillator. Figure shows a thin rectangular cantilever etched out of silicon (density 2300 {\rm kg/m^3}) with a small gold dot at the end. If pulled down and...

Can anyone help me with a general working principle for the measurement of tension in a cable?

I have to construct an experiment which measures the electric field strength at various distances from a charged Van Der Graaff generator. How would i go about this?

m=F/a then is mass measured in kg or g. Thanks

In Industry, what kind of plants would need to measure metal ions in their process streams. Ions that interest me are copper, nickle, iron etc. I've been trying to find some information, but only found some limited information on nickle but it did not include the information that I want, what...

Hi people, i got a question regarding current measurement. Is there a way to measure it, other than by putting the ammeter in series? How do they find the current output from one IC to another IC and there isn't any resistance or cap between them? Thank you.

So I am Googling around trying to figure out how one would go about taking this measurement. I have learned the 'book way' of calculating the power generated by the engine/transmission system of a vehicle; but how does one go about physically measuring it? I am learning about different kinds...

Hi, I have a question about a fact that I did't understand, and all the world takes this as it is: How can the space-time distortion, generated by gravitational waves, can be measured? All scientist say that the space is stretched and squeezed, but how much means that, because 1 meter stretched...

Let me know if there are any errors or holes in my logic, facts, or assumptions. I was thinking in regards to time being relative to the observer and the resulting impossibility of an objective measure of time: In determining the age of the universe, our current estimation is about 13.2...

Temperature is basically the movement/ vibrations of particles. They vibrate only because they are in interaction with other particles/ fields - otherwise they would just fly in a straight line. As they have kinetic energy. Temperature = internal kinetic energy. How can one measure particles...

Measuring water level in tank...?? How to measure water level in tank in the cheapest way? The first thing that came to my mind is pressure sensor... but it's ruled out because it's expensive. Can somebody suggest a cheaper mechanism? And it is preferred to have a low power mechanism...

Recently, I asked my physics teacher how to measure the height of a virtual image behind a concave mirror. He said he wasn't exactly sure so he offered to give extra credit to anyone who could find information on how to do it. Is there anyone who can help?

I'm trying to find the amount of repulsive force dark matter has on matter. To my understanding, the presence of dark matter is deduced from the fact that galaxies are being pushed away from one another instead of toward each other. The absence of matter between the galaxies suggests an...

hi... We generally use the Pythagoras formula for distance between two points in 2D, when the Cartesian co-ordinates are given... One directly extends it to 3D..having the distance going as \sqrt{x^{2}+y^{2}+z^{2}}... For a curved co-ordinate system, we have distances measured by...

I just started learning some basic measure theory. Could someone explain the difference between \overline{F(A \times A)} and \overline{F(A) \times F(A)} where A is a finite set. Also, how would this be different in A was an countably infinite set? Thanks!

Part of my independant investigation requires me to carry out an experiment, which when I graph results, would confirm Malus' Law. I plan on using a bulb as my ambient source and two polarizing lenses. I will then measure the intensity of the light after polarization. Hopefully, if i graph...

Hi I was reading about the measurement of light years and was suprised to see it is the speed at which light goes through a vaacum. Is that because of the vaacum of space or does light have mass? thanks lneilson

Homework Statement Suppose E and B are measured by an ovserver at rest to be (in N/C) E = [0,0,60] B = [0,0,0] Now another observer travels close by in the +x direction at a constant speed of v = .8c with respect to the other observer. A. What is E' be in the moving frame? DONE b...

So the current through a diode as a function of applied voltage is: I = I0 [ exp( V q / KB T) - 1 ] where V is the voltage (independent variable), q is the charge of the electron (constant), T is temperature (constant over each trial), I0 is some parameter that's measured to be really tiny (I...

Hi there, Having a bit of trouble working something out for a lab experiment at uni - not sure if this really counts as a 'homework' question - but if it does, moderators, feel free to move it there! So we've got linearly polarised laser light hitting a quarter waveplate to create...

Warning: I have a minor grasp of physics... I am devising a study looking at the tension required in a surgical prosthesis (which is essentially a length of nylon with 80LB breaking strain) to produce stability between 2 bones. The nylon will be placed in a simple loop between 2 structures and...

So we did a dry lab in class, and we were determining sources of error for a particular lab dealing with the measurement of rate of reaction. My teacher said that the time intervals of the recorded concentration was too far apart (1 minute intervals). I was wondering if anyone would explain...

Homework Statement My question is. How would the acceleration vs. time graph look if an object was in free fall? I am referring here to the picket fence lab. The Attempt at a Solution My brain tells me, that it would be a horizontal line. But when I think about it, it doesn't...

I am going to need to be experimentally measuring the stresses in a tubular steel frame. The tubular steel has a 0.75" OD and a thickness of 1/16". The frame is for a chair and I need to determine the stresses at various locations and determine whether or not the stress is below the endurance...

Hi everyone, http://img372.imageshack.us/img372/6093/img009h.jpg With the above, I really have no idea other than the standard s=d/t formula, but I doubt that has anything to do with it for a question worth 3 marks, and then looking at the two questions below, it'd make no sense. The...

I am developing a new chemical sensor. I want to test the sensitivity of the sensor to various chemicals such as K3Fe(CN)6 and Ascorbic Acid. My understanding was that you could use a chronoamperometry scan to do this measurement by injecting a controlled amount of chemical every 60 seconds...

I would like to put a cup of water in microwave and measure the temperature of the water as it rises with time in the microwave. Obviously electronic equipment will be fried in a microwave, but would it be possible to put a thermocouple in the water with its lead coming out of the microwave...

Is there a median sea level that the logs of sea level data is based? I know the moon causes the tides which upsets the equilibrium on a constant basis. I need this sea level to be based upon the distance from the center of the Earth so with the elevation of a particular city on the Planet...

Homework Statement Let's say you are given 10 identical springs. How would you develop a scale of force (i.e., a means of producing repeatable forces of variety of sizes) using these springs? Homework Equations None that I can think of. The Attempt at a Solution My guess is that...

In relativity example , a time measuring device is shown in which a ball moves up and down. This device is then placed in a moving frame and the motion of the ball is observed from the ground. To an observer on the ground, the path followed by the ball will be a slant line. And therefore when...

Homework Statement Given the following: • a battery, • a digital voltmeter (which records voltage as a function of time), • a digital ammeter (which records current as a function of time), • a battered industrial capacitor, • two copper plates, • and several bits of copper wire...

Hi, I'm trying to find out how changing the current fed through to a filament (e.g. sodium) of a lamp would change the light intensity. To determine the relationship, I will first need to find out how to measure the intensity of light. I've thought of one possible way to do it, but the...

Hi Everyone, This thread is a modified continuation of my "Digital Voltage Meter circuit " thread I started a long time ago here: https://www.physicsforums.com/showthread.php?t=180822 But with a few changes. In this case, I have a large DC capacitor that I want to monitor the voltage...

Hello All, This is a new thread related to my output stage setup. Only this time, rather than determining if something went wrong, I simply want to monitor the temperature of the MOSFET on the output stage. I have been doing a bit of research to see what kinds of sensors are available out there...

where do we use solid angle or steradian for measuring,in what way is theuseful over normal angle?

Hi All, A friend and I were recently considering the idea of measuring water flow in a fire hose, buy measuring the flux generated by the water moving through the hose. Neither of us are scientific by any means, but I've been trying to research the idea and have not gotten very far. I...

I have a project to measure young modulus by measuring the deflection of a beam under point mass. I have derived the equation but i am confused to how the end of beam should be placed to obtained best precision. Should it be both clamped end, freely supported end or a mixture of both? My idea...

Hi guys, I would like to know if any of you knows a method to determine the time it takes for a given substance to decompose. I would really like to perform such experiment, but I was not able to find anything, and I am sure this method exists, as everyone has already seen a table like this one...

Homework Statement Estimate the minimum length of time needed to measure the energy of a photon to an accuracy of 10^(-15) Joules. Homework Equations E = hv, where v is the frequency of the photon and h is Planck's constant in J*s Watts = Joules/second The Attempt at a Solution...

Homework Statement At an accident scene on a level road, investigators measure a car's skid mark to be 93m long. It was a rainy day and the coefficient of friction was estimated to be 0.32. Use these data to determine the speed of the car when the driver slammed on (and locked) the brakes...