Power dissipation Definition and 70 Threads

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...

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...

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...

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...

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...

Homework Statement Homework Equations P=F*V The Attempt at a Solution why isn't it P = Cd(A^2)(v^2) * (v) i don't see what i could do

Homework Statement a wire of resistance r is drawn to double its length. assume a constant voltage and a fixed volume, by how much does the power dissipation change? Homework Equations P=LEI E=V/L I=V/R The Attempt at a Solution so when i plug in 2L for L, it just ends up...

Homework Statement The corroded contacts in a lightbulb socket have 5.0 Ohms of resistance. How much actual power is dissipated by a 100 W (120 V) lightbulb screwed into this socket? Homework Equations P = V^2/R V = IR P = RI^2 The Attempt at a Solution I found the resistance of the lightbulb...

Homework Statement See Attachment. Find the total Current in the following circuit by phasor diagram techniques only. What is the total power dissipated?Do not use complex #'s. Homework Equations The Attempt at a Solution Im not really sure how to start and the notes for...

Homework Statement Three series elements have a.c. voltages across them of 25cos(2 \pi 60t + 30') , 15cos(2 \pi 60t + 60') , 30cos(2 \pi 60t -45') Volts respectively. The current flowing is 5.2cos(2 \pi 60t + 25')A Using phasor diagram find a)total voltage b)phase angle between...

I was asked to first find a few things using supersposition (A few voltages). Now it says to find the TOTAL power dissipated and there are two answers. Do I just find out all the currents(to find out all the voltages across each resitor)etc...and then sum up all the \frac{v^2}{R}'s for both of...

Hi all, I am trying to design a low power dissipation driver circuit. Basically the circuit gets a 1v digital signal which tells it whether to apply a separate DC power source of 100v across a 1nF capacitor. This digital signal is modulated at about 100kHz and will change at about 50kHz...

If you have a globe marked 70W and 240V and you connect it to one end of cord( which has two wires, each of 0.6 ohms), and the other end of the cord is connected to a 240V outlet, what is actual power dissipated by the globe?