What is Dissipation: Definition and 184 Discussions
In thermodynamics, dissipation is the result of an irreversible process that takes place in homogeneous thermodynamic systems. In a dissipative process, energy (internal, bulk flow kinetic, or system potential) transforms from an initial form to a final form, where the capacity of the final form to do mechanical work is less than that of the initial form. For example, heat transfer is dissipative because it is a transfer of internal energy from a hotter body to a colder one. Following the second law of thermodynamics, the entropy varies with temperature (reduces the capacity of the combination of the two bodies to do mechanical work), but never decreases in an isolated system.
These processes produce entropy at a certain rate. The entropy production rate times ambient temperature gives the dissipated power. Important examples of irreversible processes are: heat flow through a thermal resistance, fluid flow through a flow resistance, diffusion (mixing), chemical reactions, and electrical current flow through an electrical resistance (Joule heating).
I've been looking over how to find power dissipation for voltage regulators, op-amps, comparators, logic gates, and amongst other things.
Ive looked at some resources and I'm not getting what each variable means.
From what I understood so far I've seen
PDstatic = Vcc*Icc where Vcc and Icc...
i got part (a) by using the equation Vab + E - Ir
Which gives 26.57V (also the current = 1.171A)
Having trouble getting the power dissipated, any ideas?
Homework Statement
Heater dissipates 500W when applied potential diference is 110V and wire is 800C. How much power would it dissipate if the wire temperature were held at 200C?
Homework Equations
a=4.0e-4
p=V^2/R
Rf=R0(1+a(T-T0) where R is resistance after temp change...
I am currently working on a small personal project.
It is a small under-water generator/ motor so the setup is as follows. The generator and gearbox are mounted on steel struts within an air-tight nacelle of sorts which is cylindrical and made of steel. The nacelle is submerged in cold water...
there are 3 resistors of, different values. 470o,22o and 100o. but each one is 500W
I want to connect them in series/parallel in order to dissipate the maximum power 500W.
I have connected 4,22o in series and 2, 100o in series, 1, 470 in parallel. but the dissipation is not maximum.
the...
Homework Statement
Two hanging masses have an identical charge and create an angle theta from the vertical. If they start losing their charge and have an instantaneous velocity of XX m/s(given), find the rate in which they are losing the charge.
Homework Equations
Coulumbs Law
The...
I'm sure you all know what I mean by tidal dissipation function but it's...
Q = \frac{2 \pi E_0}{\Delta E}
and describes how much dissipation is produced. \Delta E is the energy lost over one cycle and E_0 is the peak energy stored during the cycle.
So my questions are:
How do we estimate...
Hey guys, so I have a homework question that I have already solved one way, but when I try it another way I can't seem to get the correct answer.
First of all, the question is:
"A single resistor is wired to a battery as shown in the diagram...
Homework Statement
The following is a diagram of dc power supply with a Zener diode regulator. For what load current is the power dissipation of the Zener diode maximum? How would you find the approximate value of this maximum power dissipation...
Homework Statement
The current through a resistor is i(t) = 2sin(30t + 169°), and R = 50Ω
What is the power dissipated by R at t = 3.7ms?
Homework Equations
p = i2R
or
p = .5(Vmax)(Imax)*(cos(\phi-\theta)+cos(2*\omega*t+\phi+\theta))
The Attempt at a Solution
I feel stupid...
If I ran over a problem asking for power supplied by a non-ideal battery, or a battery with an internal resistance. Do I account for the internal resistance when I calculate the power dissipation? Or do I just account for the loads (finding the total resistance excluding the internal...
Hi,
I´m trying to figure out how light intensity diminishes when traveling through air. I assume absorption/scattering are responsible. But how far can a single light ray travel, and what mechanisms are in place that causes light to lose its energy. I´m trying to come up with a relationship...
can anybody please help me to understand some of the things regarding tire dynamics?
first of all , while tire is rotating on a road, what are the factors to be considered to find the contact area, and slip area?
second, dissipation, what is the main factor that lead to dissipation , is it...
Hi,
First time posting. I have some scattered notes that I found on applying physics to horseracing. One of the notes talked about the energy dissipation of each horse's prior races but no formula was given. Could anybody show me how to calculate the energy dissipation for each horse in the...
I haven't had the pleasure of being on this site as much as I should be...pardon that. Either way, on with it then:
I would like to begin this article with a question regarding the actual nature of gravity. Relative to massive bodies, it seems that gravity exerts a force that in general...
Hi all
I've found a way to include dissipation in the kinetic energy of the lagrangian for simple systems and I want to know if its ok to do this. My understanding is that dissipation is typically included using the Rayleigh dissipation function which is separate from the Lagrangian.
The...
Homework Statement
What is the power dissipated in the 34-Ohm resistor?
Homework Equations
P=RI^2
The Attempt at a Solution
I have found the total current in the system as well as the current through the resistor, and keep getting 1.88, which is incorrect. Any suggestions on...
Is there a relationship between the heat dissipation of a processor and its speed? I am guessing there should be. If there is a relationship, is there any mathematical formula to deduce the heat dissipation of a processor?
So, hypothetically if we had a spaceship of some kind using a nuclear fission reactor for power, in order to dump the waste heat into space, how big of a radiator would be needed? How much heat, in watts, can be dumped per square meter of radiator in a vacuum?
When a capacitor is charged by a battery half the power is dissipated as heat and half is stored as potential energy within the field of the capacitor. Similarly a resistor dissipates all power that the battery supplies.
Now here's my question: In an RC circuit where is the power dissipated...
Homework Statement
Lightbulbs labeled 40 W, 60W, and 100 W are connected to a 120 V/60 Hz power line as shown in the diagram. What is the rate at which energy is dissipated in each bulb?
Homework Equations
Pr = (Vrms)^2/R
The Attempt at a Solution
I'm not exactly sure how to...
I guess it is common to say spring system conserve energy.
But recenetly i hav been wondering another thing.
Everybody have the experience of compressing a spring.
When you do so, you must pay a force to keep the spring compressed.
However, when you exert that force, you must also...
I want to estimate the power of a CMOS inverter circuit. I want to ask that is there any software for simulation purpose to give the power of CMOS inverter.
The second problem I have is that when you calculate the dynamic power of CMOS
dynamic power = Vdd2*CL*f
This dynamic power depends...
Hi there, new to the forum. Just finished my Electrical engg. undergrad at the University of Calgary. Anyway I had a question regarding thermal transfer in a vacuum.
Over my internship I did a substantial amount of work with cooling electronics using heat sinks and/ liquid, so I have a fairly...
Homework Statement
For the circuit shown, find the power dissipated by the 10.0 ohm resistor.
(as attached)
Homework Equations
P=IV=I2R=V2R
V=IR
The Attempt at a Solution
I really don't know where to start with this. I'm basically tied up in the fact that there are three...
Hey guys. i am on a little project here, may i know hot to calculate heat dissipation from processor and HDD ? is it using P=I^2R will do ? if so what is my R and I?
A potential difference V is applied to a wire of cross-section area of 1 unit, length 1 unit,
and conductivity σ. You want to change the applied potential difference and draw out the
wire so the power dissipated is increased by a factor of 30 and the current is increased by a
factor of 4 .
a)...
1. The 10 ohm resistor in the figure is dissipating 40W of power. How much power is the 5ohm resistor dissipating?
2. P = I2*R
3. I = sqrt(P/R) = 2. I then did P = I2R = (4)(5) = 20 which is incorrect.
Homework Statement
A single resistor is wired to a battery as shown in the diagram below. (Figure 1) Define the total power dissipated by this circuit as P(subscript 0). Now, a second identical resistor is wired in series with the first resistor as shown in the second diagram to the left...
Homework Statement
My physics teacher (i'm in year 12) set me a "challenge" to prove a graph in our textbook, which shows Power against Resistance, with a local maximum where R = internal resistance, r. He told me i'd need to use differentiation, P = I^{2}.R
and said that I was right in...
I am looking for a resistor that can dissipate a constant amount of heat at all temperatures immediately.
I have been using some metal film/oxide resistors, but it takes a very long time before the resistor starts radiating heat. I think the material making up the resistor has such a high...
Question requires a definition and typical values during normal/abnormal operation (Power dissipation of 20A Diode with 1V across it)
Have got definition no problems, but am struggling with typical values.
Power dissipated would be in watts, but in order to provide that you would need...
I am struggling to calculate the required resistance of a single seater race cars nosecone in the event of a head on collision to the nosecone.
The data I have been given is:
Mass of car: 300kg
Velocity at impact: 7ms^-1
Impacting to a non-yielding barrier
Length of nosecone 0.3m
Peak...
A resistor draws a current i=8sinwt at a voltage of v=200sinwt. Calculate the average power dissipated in the resistor.
What i did is p=ui = 1600sin^2 (wt) and i got stuck:P i don't think it's the right equation.. the answer should be 800W .. and that's nothing like it.
Could someone help me ?
1. A certain car has an engine that provides a maximum power P_0. Suppose that the maximum speed of the car, v_0, is limited by a drag force proportional to the square of the speed (as in the previous part). The car engine is now modified, so that the new power P_1 is 10 percent greater than the...
Does the heat dissipated in a resistor necessarily depend on the direction of current through it? As far as I know the heat dissipated equals square of the magnitude of current thru resistor multiplied the resistance of the resistor. But it seems direction matters.
Homework Statement
The instantaneous power dissipated by the damping force in a driven oscillator is P(t) = f_x v_x = -bv_x ^2.
Show that the average power dissipated during one cycle of steady-state motion is \overline{P} = -\frac{1}{2} b\omega^2 A^2, where \omega is the driving frequency...
I have found a possible mistake in my book...here's the text which contains it,
"Referring to figure, it can be seen that no power is disspated in a pure inductor. In the first quarter of cycle, both V and I are positive so the power is positive, which means that energy is supplied to the...
Homework Statement
while surfing the internet i stumbled upon the following question:
Why ac(alternating current) is used to power houses instead of DC?
Answer:The answer lies in the transmission lines for the electricity. The wires have a defined resistance, and when current passes through...
Hello!
I'm trying to make sense of what is probably simple. Imagine I have an IC package that is rated to dissipate at most 1 Watt. The thermal resistance from case to ambient is not known (could maybe be generalized).
I have a heatsink that has a thermal resistance of 20°C/W. Can I...
Homework Statement
A string of 19 identical Christmas tree lights
are connected in series to a 120 V source. The
string dissipates 60 W.
What is the equivalent resistance of the
light string? Answer in units of ohms.
What is the resistance of a single light? An-
swer in units of ...
Homework Statement
Homework Equations
P=IV
I=V/R
P=(V/R)V
R=V2/R
The Attempt at a Solution
PR1: 122/12=12
PR2: 144/18
I'm not sure what to do from here. Thanks for any input and help!
Homework Statement
Two 10-cm-diameter metal plates are 1.0 cm apart. They are charged to +/-12.5 nC. They are suddenly connected together by a 0.224-mm-diameter copper wire stretched taut from the center of one plate to the center of the other.
d)What is the total amount of energy...
I am doing an experiment to study how different factors affect the time taken for ripples to dissipate in water.
I have been using the mass of metal ball bearings as a variable and changing the height from which they are dropped as well to create the ripples.
To measure the time taken for...
I'm having a really hard time wrapping my head around this. A capacitor in an AC circuit will charge and discharge with respect to the frequency of the signal voltage. Impedance in the circuit is proportional to this frequency and its capacitance. In a power supply the current is regulated...
I'm trying to get a better understanding of they heat dissipation properties of these two materials. Understanding that there are many different kinds of nylon and steel, what are some general rules of thumb?
Thx.
What equations would I need for calculating this, say if I wanted to know what the power/intensity of an x watt, x wavelength laser would be reduced to after x metres?
What is the dissipation due to heat conduction?
D = -k \frac{\vec q\cdot\nabla T}{T}
where q is the heat flux, k is the
coefficient of heat conduction and T is the absolut temperature.
What is the physical meaning of this?