Homework Statement
The far point of a nearsighted person is 6.0 m from her eyes, and she wears contacts that enable her to see distant objects clearly. A tree is 18.0 m away and 2.0 m high. (a) when she looks through the contacts at the tree, what is its image distance? (b) How high is the...
Homework Statement
The drawing shows a crystalline quartz slab with a rectangular cross-section. A ray
of light strikes the slab at an incident angle of 1=34o, enters the quartz and travels to
point Po (Figure2). This slab is surrounded by a fluid with a refractive index n...
Homework Statement
The drawing shows a charged particle (q=2.80x10^-6C) moving along the +y axis with a speed of 4.80X10^6 m/s. A magnetic field of magnitude 3.35x10^-5 T is directed along the +z axis, and an electric field magnitude 123 N/C points along the -x axis. Determine the (a)...
Homework Statement
Three identical capacitors are connected with a resistor in two different ways. When they are connected as in part A of the drawing, the time constant to charge up this circuit is .34s. What is the time constant when they are connected with the same resistor as in part B...
ok this is what I have so far.
20V= (I*1680)+(I*R)
30V=(I*2930)+(I*R)
(I*R)= 20 - (I*1680)
(I*R)= 30 - (I*2930)
(I*R)=(I*R)
20 - (I*1680)=30 - (I*2930)
I=125
But then when I plug 125 back into the two equations to solve for R, I get different values for R in each equations. Looking at the...
Homework Statement
Two scales on a voltmeter measure voltages up to 20.0 and 30.0V, respectively. The resistance connected in series with the galvanometer is 1680 ohms for the 20.0V scale and 2930 ohms for the 30.0V scale. Determine the coil resistance and the full-scale current of the...
So using the equation without the current:
P=V^2 / R
P1=V^2/(R=r)
So according to the example vk6kro suggested:
V=12 R=15
P=12^2 / 15
P=9.6
(9.6)(.1)=.96
9.6-.96= 8.64=P1
P1= V^2/(R+r)
8.64 = 144/(9.6+r)
r=7.07
r/R=7.07/15=.471
I still don't understand how you can find the ratio algebraically...
so:
Rs=R+r
P1=I^2 Rs and P=I^2 R
I'm pretty sure I've understood everything you have said physics wise regarding the problem, but I don't understand how to come up with the answer when the only number I know is 10%. The only difference I see when comparing the two P's is that in P1 I^2 is...
1. P=I^2 R
2. 1/Rp = 1/R + 1/r
3. to find the power dissipated in situation 2 I would use the equation:
P=I^2 Rp
because they are parallel resistors. So the difference between the to powers is one is multiplied by R and the other by Rp. If I did do everything right I don't understand how...