# Questions tagged [laboratory-safety]

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### What does 0 volts mean for a Van de Graaf generator?

I am trying to understand how two different definitions of zero-voltage reconcile in the experimental setup of a Van de Graaf generator, or at least how I understand that it is being described. ...
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182 views

### Is it safe to heat completely sealed vacuum container for a long long time?

I am currently making vacuum fryer, and was wondering this question. Normally, when you apply heat for a long time in a completely sealed container, the gas will expand, and pressure will be built and ...
1 vote
265 views

### What is the size of the beryllium in the Demon Core?

The Demon Core is covered by a hemisphere of beryllium. The Demon Core reaches criticality when the beryllium is completely closed. To achieve this, the size of the beryllium must be adjusted so that ...
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1 vote
41 views

### Laser safety of standard laser pointer diode [closed]

I am thinking about designing vector display with standard pointer laser diodes. I would make display be diffuser of some sort like milky glass or paper, but I want to make it see through, rather than ...
80 views

### Evaporation time for a Mercury-Ball

How long does it take for a Mercury-Sphere to evaporate, if it has a diameter of 1mm and the temperature is 25 Degrees Celsius and the air moves at a speed of 1km/h over it? What would the formula for ...
216 views

### Using grams instead of kilograms in terminal velocity equation

I am conducting an experiment verifying the relationship between terminal velocity and other factors: $v_t = \sqrt{\frac{2mg}{\rho AC_d}}.$ (All values in SI units.) Suppose that I have all my ...
23k views

### Is it safe to keep uranium ore in my house?

I bought 5.6 gr of uranium ore. The measured gamma radiation is 1µSv/h, we didn't have the instruments to measure alpha/beta radiation. EDIT: The gamma radiation was measured at 1cm distance. I also ...
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1 vote
70 views

### Fresnel lens safe viewing distance

I work for a summer camp, and we have a Fresnel lens that is roughly 18in x 24in. I'm writing a safety document for the device, and am attempting to find out the minimum safe viewing distance without ...
1 vote
269 views

### Laser line safety

I'm a researcher at University Federal of Santa Catarina Brazil and I work with lasers. I'm looking for information about how to calculate the Nominal Ocular Hazard Distance (NOHD) to a laser line and ...
176 views

### Is it dangerous or safe to use a black/dark cloth cover on a propane tank? [closed]

Say I have a standard 20lb propane tank. I want to put a protective cover over it, to shelter it from weather. Can I use a cover that is black or dark colored? Is that dangerous or will it put me at ...
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5k views

### Is it dangerous to put a pressure cooker under cold water after cooking?

After cooking using a pressure cooker, it usually takes a while for the pressure to be released and for the cooker to be opened. However when I think the food may have been slightly overcooked, I take ...
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359 views

### Why connect plug wires in a certain way when polarity changes in AC anyway? [duplicate]

In AC systems the two wires of a circuit alternate polarity many times per second. So positive and negative switch, half of the time a wire is positive the other it is negative. So why is it ...
3k views

### How much radiation do nuclear physics experiments expose researchers to nowadays?

I am curious about how much radiation do experimental nuclear physics researchers/students suffer in nowadays research environment. I know this may be a dumb question, but I have can found answer ...
6k views

### Is a 1 cm thick obsidian glass plate safe to see the Sun direcly? [closed]

Is a 0.5 cm thick obsidian plate good for seeing the Sun directly?
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### What is a good introductory textbook to Laser Safety?

I was looking for a good textbook about Laser Safety (e.g. protection glasses design, distance of risk calculation, laser classification...). I can't find a complete book with these informations, ...
1 vote
302 views

### Is discharge tube dangerous?

Are those gas discharge tubes dangerous? I found atom spectra interesting, so I booked a 1.5 hour lab session at a local high school. The physics teacher gave me a few hydrogen tubes, helium tubes, ...
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1 vote
2k views

### How are these utensils microwave-safe? [closed]

These types of utensils are starting to become popular nowadays. I checked their product description which says that its outer surface ( i.e. the red part) is microwave-safe plastic while the inner ...
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269 views

### Carrying 10 liter dewar in elevator advisable? [closed]

I am using liquid nitrogen a lot at university and frequently have to carry a 10 l dewar from the storage container into my lab. On this way I have to walk down 4 stories with the heavy dewar. ...
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1 vote
66 views

### Amplifying stress at near perfect vacuum?

So, I've got a vacuum chamber as part of a home freeze drying project. It is a cylindrical steel pot with a 1.5in acrylic lid. The manual is poorly translated from Chinese, so some of it is seemingly ...
788 views

### Does a fusor emit dangerous radiation?

I noticed some online videos where people have built these things in their house or garage. Is it dangerous to do so? The high voltage appears to be a potential hazard, but what about radiation -- ...
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44 views

### How to pass a fiber optic through an aluminum laser enclosure?

This is a very technical question which I think is not typical on this site but it is for experimental physics so I'm trying it out because I can't find a better stack exchange Problem I'm trying to ...
228 views

### How dangerous is a neutrino experiment near human habitation? [duplicate]

I just read about people trying to capture neutrinos and study them. America has a lab in Antarctica and France deep under the ocean. Is it dangerous to conduct such an experiment where people live or ...
1 vote
1k views

### What is the relationship between AEL, Class, and MPE for laser safety?

I'm trying to establish safety limits for a laser system but can't resolve the information in the ANSI manual. Here is my understanding so far: MPE (Maximum Permissible Exposure) is based on health ...
1 vote
2k views

### A safe way to heat batteries

I'm working on a physics experiment where I have to investigate the effect of temperature on a battery's internal resistance. I know how to measure the internal resistance, but the problem is in ...
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### Safe Laser displays

I hope this is in the right stack exchange. Here's my question, assuming that all blue lasers are too risky to the eye to risk [using], is it possible to use only low-energy red and green lasers and: ...
108 views

### Calculating the electrical current in a Crookes Tube

I am planning on building a Crookes tube with the machine shop in my university's Physics department. I have pretty much all the details worked out, but since the tube has to operate at a high voltage ...
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1 vote
347 views

### Why don't laser safety goggles filter out the dot completely?

I was using a pair of these safety goggles which appear to be quite popular among laser hobbyists: http://www.survivallaser.com/Eagle_Pair_190540nm_OD5_Standard_Laser_Safety_Goggles/p556088_2780808....
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139 views

### Viewing totality though an unfiltered telescope [closed]

DISCLAIMER: This question is for informational purposes only and the ensuing discussion must not be construed as safety advice. There seems to be a consensus among experts that partial eclipse should ...
4k views

### Is looking at an eclipse worse than looking at the sun? [duplicate]

I understand why looking at the sun is bad. I also understand that looking at the eclipse is bad. Is it more dangerous to glance at an eclipse than the sun, assuming you avert your eyes right very ...
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40k views

### Why aren't 100% UV blocked sunglasses safe to view an eclipse with?

I am not planning on staring into the sun during an eclipse or any other time. I have been reading about how no variety of regular sunglasses are safe enough to view the eclipse with. I'm not talking ...
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### Why can I look at the sun with my sunglasses but not at the solar eclipse?

Is the problem with seeing an eclipse that you have a sudden change between penumbra and regular sun? If that's the case, why can I look to the sun with my sunglasses on but I can't do it in an ...
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### Can two polarized glass filters held at near 90° orientation serve as safe eclipse glasses? [closed]

Using two polarized filters to block all (?) light is a common classroom demonstration. With the imminent north American total eclipse, the media has been pushing eclipse glasses and emphasizing the ...
1 vote
95 views

### Safety in ultracapacitor discharge regarding possible effects of induced voltages

Problem I am trying to analyze the safety of two experiments involving ultracapacitor short-circuit discharges. In the first experiment one has a discharge of a $0.45 \,\mathrm{F}$ capacitor with ...
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### Can a 808nm laser diode with power = 400mW burn skin?

I have a 808nm laser diode with a spot size of 0.4mm and output power = 400mW, Can it burn the skin or hair if the exposure duration = 10ms?
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### An appropriate way to store neodymium magnets

Okay so I've bought a few small neodymium magnets to play around with, they're very powerful and I really like them, but I was wondering what's the actual best way of storing those magnets in a way ...
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333 views

### Are noise cancelling headsets safe? [closed]

Older microlight headsets such as the Lynx Micro System are modelled on ear defenders and physically attenuate the noisy cockpit environment by clamping hard onto your noggin. Most modern GA headsets (...
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264 views

### What are the possible dangers of removing the microwave shielding?

Would removing the shielding from a domestic microwave door allow the microwaves to cause damage to a consumer grade video camera, and if so, what damage would it cause?
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### Carrying A Couple of Grams of Uranium in Pocket - Was it Dangerous?

In short: I handled a small amount of uranium when I was young and kept it next to me in a bottle for years. Should I be concerned? The background is that when I was a young (10-ish), I was growing ...
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270 views

### 7 W medical laser without any precautions?

Today I got some medical laser treatment to treat some tendon irritation. The doctor used a red or IR laser with 7 W of power. He casually applied the laser onto the knee and was panning over the area....
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910 views

### Antique X-Ray Tube Safety

I have this antique X-Ray tube in my lab. As far as I can tell it's a “Kesselring” free anti-cathode tube from about the 1920s. Is there a safe way to operate this tube and make some x-rays or is ...
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2k views

### Why are UV protective eyeware Orange?

Many industrial processes use uv as a curing agent. When one uses such a process, one must protect one's eyes from the radiation. Most uv protective gear I have seen is tinted orange? Does this ...
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494 views

### Can a high-watt laser's scattering light be damaging to the eyes? [closed]

Heyo, I recently purchased a S3 Arctic Class IV laser pointer. I bought the 3500mW. (In case that page expires, it's 445nm wavelength, 1.5mRad variant, NOHD is 279m, beam distance at 0.25 Lux 72km.) ...
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476 views

### Why didn't 0.2A at 2V kill me? [closed]

I was recently connecting a circuit together like here: and I had the voltage set at 2V, with a 10Ω resistor. By Ohm's law, there was a current of 0.2A (and was confirmed by my multimeter). I ...
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571 views

### How to determine the strength of a laser beam needed to cut through a specific material?

How can it be determined how strong a laser beam needs to be in order to cut through specific material? For example, if I have a 5mm thick piece of brown cardboard, is there a way to determine how ...
27k views

### Does a laser beam have to hit the eyes in order to damage them?

Does a laser beam have to hit the eyes in order to damage them? Or can a persons eyes get damaged by looking at a beam that goes past their eyes (e.g. looking at a laser beam moving inside an ...
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### How to choose laser goggles for low-power laser of specific wavelength?

I need to choose laser goggles to shield eyes against 678 (+/-8) nanometer laser (5mW power). The laser has a red beam. I found for example some goggles that are sold for 650nm, with a blue lens. ...
1 vote
235 views

### Polonium tea emergency [closed]

Let's assume that I just realised that tea I drunk 30 minutes ago during meeting with a secret agent was doped with radioactive polonium. What should I do? What the doctors will do? Are there ...
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109 views

### Any economical quantitative electrostatics experiments for the university level?

I'm seeking for some safe experiments for undergraduates in the electrostatics context. We have a Van-de-Graaff generator in our fundamental physics lab but this kind of devices are useful for ...
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1 vote