PHY 114 Lecture Notes - Lecture 9: Kelvin Mercer, University Of Manchester, Microsoft Powerpoint

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15 Mar 2018

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A capacitor is charged to an initial voltage of v0 = 9. 0 volts. The capacitor is then discharged through a resistor. The current is measured and shown in the figure below: Find c, r, and the total energy dissipated in the resistor. The current is (cid:3010)(cid:3116)(cid:3032) = 36. 8 ma at t = 13 msec. Since e = v0 = 9. 0 volts, then we can find that r = 90 ohms and. C = 144 f using the equations above and the found values of the 36. 8 ma after 13 msec. Just try plugging them into your calculator to see how it"s done. = 13 msec = r * c. All of the energy stored in the capacitor is eventually dissipated by the resistor, and we can use this equation to show it: U = (cid:2869)(cid:2870) (c * v02) = 5. 8 x 10-3 j.

Related Questions

I'm feeling really tiered and just can't think, please help if youcan. I might seem a bit lazy but I really don't feel well and thisis in for tomorrow :( :

1) with the aid of a sketch graph, describe how the resistance R ofa negative temperature coefficient (NTC) thermistor changes withtemperature T. (2marks) please explain how I should do thecurve/line of best fit for the graph thanks.

2) state how, and explain why, the resistance of the filament lampchanges as the p.d across it increases.

3) calculate the total resistance of the series combination of thefilament and the resistor.

4)calculate the internal resistance of the supply.

5) use fig 3.1 to calculate , for a p.d of 3v,
(I) the current in the lamp.
Answer:
I= V/R= 3/50=0.06 A

(ii) the power dissipated by the lamp.

6) suggest why the resistance of the lamp doesn't changesignificantly over the range of 0 to 2v.

7) the tungsten filament lamp is at room temperature when the p.dacross it is zero
I) state the resistance of the lamp at room temperature.

Thanks.

We are doing an experiment in my physics lab that involves trying to find the horizontal component of the Earth's magnetic field. Here is a little explanation of what is going on: We have a bar magnet that is placed inbetween a set of Helmholtz coils (125 of them coiled) and we place a certain current (i) on the coils. We then see that the bar magnet begins to try to align itself with the magnetic field, but it will have an angular momentum that will cause it to continue turning past the direction of the magnetic field creating oscillations. Our instructor told us to count 25 oscillations and find the time it takes for 25 to occur. From that we can then find the period of oscillations(T) from each current. Then we can find 1/T^2 from this. We then plot a graph with current(i) on the x-axis and 1/T^2 on the y axis and we find its a straight linear line. Our Instructor stated that the y-intercept will be our b and our slope will be S. From the equation given in our packet which is: (32pN x 10^-7/r x radical 125) x b/S. I know that N is the number of coils, r is the radius(9.6cm), b is the y-intercept, and S is the slope. However, from my graph, my equation for the line of best fit was y=0.967x - 0.3068. plugging this in (32p(125) x 10^-7/9.6cmx radical 125) x (.3068/.967) I get 4.643x10^-4. Putting this into gauss by multiplying times (10^4) i get 4.64 which i know is far off since NASA says its around 0.2-0.5 gauss average around Earth. I would really appreciate the help for what im doing wrong.

PHY 114 Lecture Notes - Lecture 9: Kelvin Mercer, University Of Manchester, Microsoft Powerpoint

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