# All Questions

1answer
65 views

### Does car colour affect car temperature? [duplicate]

My family will buy a car, so to minimise the car's air conditioning and heating (and thus fuel) costs, how should we choose a car exterior's colour and the interior's colour and material (eg fabric ...
2answers
44 views

### At what point do researchers in physics make the leap from wild theoretical ideas to physical experiments? [on hold]

Dark Matter, on the surface, appears to be a wild idea... Some invisible thing that we can't see that controls the movement of most of the universe. Yet, we are searching for it. Why? What evidence ...
0answers
15 views

### Real representations of chiral fields

Why we can´t have real representations of chiral fields, i.e. why does a multiplet of chiral field (Weyl spinors) under a real representaiton of a Lie Group transforms as a "vector". It is easy to see ...
2answers
68 views

### Birds and cables: how is the potential difference between two diff. cables established?

The common explanation of why birds don't receive a shock when standing on high tension cables is that there needs to be a considerable potential difference between both of his feet for him to receive ...
2answers
50 views

### Why can't dark matter be baryonic?

Here's what I know about dark matter: Astrophysicists realized the movements of galaxies and other astronomical bodies cannot be explained by the gravitational effects of matter known to be there, so ...
3answers
76 views

0answers
31 views

### What are the most likely technology advancements that will result from NASA manned missions to asteroids & Mars? [on hold]

The Apollo missions required development of various devices that are now widely used, such as CAT scanners, microchips & integrated circuits etc. (more here) Do we know what are the main problems ...
0answers
16 views

### Ohmic contacts in a diode (metal-semiconductor junction) - contact difference of potential $V_0$ - how to compute

I'm reading "Microelectronics" by Millman, Grabel. Premise: The book developed, for a pn step-graded junction, the contact potential as  V_0 = V_T \text{ln} \frac{p_{p0}}{p_{n0}} = - V_T ...
1answer
32 views

### Ways to measure the focal length of a convex lens with only natural sun light [on hold]

What are the common ways to measure the focal length of a convex lens with only natural sun light?
0answers
34 views

### Measuring audio signals with a digital volt-meter [on hold]

Is a digital volt-meter suited for measuring audio signals, I know audio signals are measured in frequencies, is it possible/ideal to use a digital vm or something else will be better ?
2answers
41 views

### Difference between energy levels and bands of energy

As per the notes of my Solid state physics, band gap arises when the two atoms come close to each other so that their discrete energy levels split and become continuous which gives rise to bands of ...
2answers
87 views

### How do I calculate the most probable orbital an electron is in?

If I saw a snapshot in time of an electron near a proton (Hydrogen), then the electron can be in any orbital as long as it doesn't lie on a node of the wave function. So how would I determine which ...
0answers
16 views

### Loud, low-frequency “booming” sound in car [duplicate]

I drive a Scion XD, and I've noticed that whenever I drive at about 40mi/hr or so with just the back windows rolled down, I get a loud "booming" effect at roughly 10Hz. What causes this? I assume it ...
0answers
26 views

### Block slides down smooth hemisphere: WHEN will it leave surface? [on hold]

A block is at rest at the top of a frictionless hemisphere of radius r. It is slightly disturbed and starts sliding down. WHEN will it leave the surface of the hemisphere?
1answer
123 views

### Why should we believe in clock hypothesis?

It is often assumed in special relativity that the rate of a clock in a non inertial frame does not depend on the proper acceleration of the observer. The point is, Rindler's observer shows us that ...

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