The biophysics tag has no wiki summary.
4
votes
1answer
171 views
Voltage drop over a cell membrane
Again, a problem from exam preparation:
[A] cell's membrane allows sodium ions to pass through it, but not chlorine ions. The cell is placed in a salty solution with a ten times higher ...
6
votes
3answers
448 views
Do eyeballs exhibit chromatic aberration?
Fairly straightforward question. If not, why not?
I suspect that if they do, it is not perceived due to the regions of highest dispersion being in one's region of lowest visual acuity.
0
votes
1answer
93 views
People eating and gaining energy
Let's say we have 100 grams of chocolate which has 571 kilocalories (so it's about 2.4 megajoules) and we have barbell which weights 100 kilograms and need to lift it to 0.5 meters height.
So how ...
6
votes
1answer
697 views
What are the characteristics of the magnetic field surrounding a human brain?
The human brain is said to produce a magnetic field resulting from the action potentials released inside the brain. What's the nature of such a field in terms of size and strength, and what is the ...
1
vote
2answers
215 views
Running: Determine how much more energy is needed per extra kilogram of weight
(I recently asked this on maths but was directed here)
I have recently become a runner and having a keen interest in kinematics I'm very interested in the maths/physics of my running.
Can someone ...
5
votes
1answer
1k views
Adverse Health Effects of Strong Radio Waves
A while ago, I was hiking near the Hollywood Sign in Los Angeles. When I got to the sign, I found out it was fenced off; with several signs and a security camera promising prompt enforcement. As I was ...
5
votes
1answer
2k views
Newton's color Disk
How does Newton's color disk work?
Newton's disk - Take a circular white color disk, make 7 equal intersections and paint section with respective VIBGYOR colors, now when you spin the disk in certain ...
3
votes
2answers
257 views
How do animal perceive distances with their eyes and ears
I am studying how animals (including the human beings) can perceive distances thanks to their eyes and their ears. I am focusing on the fact that they always go in pairs: two eyes, two ears, etc.
...
6
votes
2answers
367 views
Quantum Computing and Animal Navigation
Someone sent me this link to a talk by Prof. Klaus Schulten from the University of Illinois: (my emphasis)
Quantum Computing and Animal Navigation
Quantum computing is all the rage nowadays. ...
6
votes
2answers
930 views
Are regular light bulbs better for the eyes than CFLs or “tube lights”?
I've heard that regular light bulbs with a filament are better for the eyes. Is the spectrum of one worse than the other? If so, are there any regulations for their use in industrial settings for ...
4
votes
2answers
374 views
Examples of circuitry using proton currents
Proton cuircuits and proton motive force are part of standard discussion in biology and processes involving photosynthesis. The sort of proton currents discussed in biology are obviously slightly ...
4
votes
8answers
569 views
Is relativity necessary for the existence of life?
If the universe didn't have the relativity principle, would it be able to support life?
Life consists of very complicated organisms. The operation of these organisms depends on the laws of physics.
...
6
votes
2answers
928 views
How are the calories in food calculated?
This is intended to be a fun question. Calorimetry used for calculating the heat generated from chemical changes has been around for centuries, however, I suspect the process for calculating food ...
2
votes
1answer
254 views
Entropy of a polymer contained in a sphere with infinitely thin chords
Imagine that I have a polymer (approximated as a freely diffusing, freely jointed chain with some number of subunits 'N'), and I place this polymer into a sphere of some volume 'V'. Next, I proceed to ...
6
votes
0answers
197 views
Predicting the ratio of translational diffusion coefficients for a sphere and a sheet
Imagine that I have a spherical particle of molecular weight $M$, volume $V$, and some experimentally observed center-of-mobility translational diffusion coefficient $D_{sphere}$ in water. I take ...
4
votes
2answers
546 views
A quantitative explanation of EM coherence domains in liquid with DNA
I've been looking with interest at a recent biology paper claiming that DNA molecules give off electromagnetic signals which can cause the same types of molecules to be reconstructed at a remote ...
8
votes
5answers
886 views
What happens to light after it enters an eye
What happens to the light [energy] after it enters an eye and hits the rods and cones? I presume the energy becomes electrical, and it must be near 100% perfect, else our eyes would heat up? Or am I ...
2
votes
2answers
700 views
Why can you see a light in the location that the light source just left?
This is my first question on this site so forgive me for the awkward wording of the question. Basically, my question is why does light from, say, a sparkler, seem to remain where it just came from to ...
21
votes
7answers
3k views
Why does holding something up cost energy while no work is being done?
I read the definition of work as
$$W ~=~ \vec{F} \cdot \vec{d}$$
$$\text{ Work = (Force) $\cdot$ (Distance)}.$$
If a book is there on the table, no work is done as no distance is covered. If I ...
12
votes
1answer
382 views
Is colour, as represented using primary colours, accurate only to humans?
Slightly biological, hopefully physical enough to be answered.
Suppose a magenta hue is represented by a mix of red and blue pigment. This is all very well for a creature with red and blue ...
6
votes
2answers
548 views
What physical forces pull/press water upwards in vegetation?
Each spring enormous amounts of water rise up in trees and other vegetation. What causes this stream upwards?
Edit: I was under the impression that capillary action is a key factor: the original ...
