Energy & Environment

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Oil Sands (a.k.a. Tar Sands)

Keywords: fluid-particle physics, Oilsands, Stokes' Law

How do you separate bitumen from sand with the least energy cost?

Separating bitumen from sand involves the clever use of simple fluid physics.

5 years 51 weeks ago

Radioactive Milk

Keywords: activity, dose, nucleosynthesis, Radioactivity

Milk contains enough radioactive potassium-40 to set a Geiger Counter humming. But it didn't come from Fukushima, or any human activity.

Milk (and own bones) contains a lot of ancient radioactive potassium-40, which was made in a supernova explosion about five billion years ago.

6 years 7 weeks ago

Why can't you just turn a nuclear reactor off?

Keywords: nuclear reactor, shutdown

When a nuclear reactor gets into trouble, what's wrong with hitting the off switch?

When a uranium nucleus fissions into two, the resulting nuclei are not stable; they continue to decay and generate heat long after the fission chain reaction has stopped.

6 years 8 weeks ago

What is a millisievert?

Keywords: dose, human health, ionizing radiation

One Sievert means exposure to enough high-energy electromagnetic radiation to deposit one joule of energy in one kilogram of living tissue. A millisievert is 1/1000 of a sievert. But how dangerous is it?

The measure of ionizing radiation dose, as is applicable to human health, is the Sievert (Sv). One Sv implies a health impact equivalent to one joule of X-rays being absorbed by each kg of living tissue. Activity, the mean number of decay events per second, is measured in Becquerels (Bq). Knowledge of the activity, mean energy release per event, and exposure time, allows to estimate the dose.

6 years 9 weeks ago

Energy Efficiency and the Jevons Paradox

Keywords: consumption, efficiency, energy, jevons, solid state lighting

Will increasing efficiency really reduce energy consumption?

Increases in energy efficiency have been shown to increase, rather than decrease, consumption.

6 years 28 weeks ago

Heating Efficiency

Keywords: efficiency, electric, energy, gas, power

Which is better: gas or electric heat?

Calculating or measuring efficiency means tracking the power all the way from source to end-user.

6 years 35 weeks ago


Keywords: transformer, voltage

Electrical energy is transmitted at high voltage. Which element creates the 120 V that is available in our wall plugs ant home?

Transformers operate on principles of electromagnetism to step up and step down voltages. This allows for efficient transmission of power across the grid to homes and buildings. It also ensures that the voltage from our sockets is appropriate for home and appliance use.

6 years 39 weeks ago

Transmitting Electricity

Keywords: power, resistance, resistivity, transformer, voltage

If high voltage is so dangerous, why do we transmit electricity that way?

Transmitting power at higher voltages ensures that power can be transmitted over long distances with minimal losses; if transferred at a low voltage, the transmission distance has to be greatly minimized, which is impractical.

6 years 40 weeks ago

Heat Balance in the Human Body

Keywords: calories, energy, energy use, evaporation, metabolic rate, power, sweat, thermal radiation, thinking

How much energy does our body use? How do we keep cool when it is really hot out? Can we justify eating more when studying?

Treating the human body as a thermodynamic system, with food energy going in and heat flow due to radiation, convection, evaporation and conduction, we can see how we can maintain a constant core temperature in a huge variety of environmental conditions.

6 years 40 weeks ago

Generating Electricity

Keywords: coils, electricity, electricity generation, magnetic field, magnets

Generating electricity using just a magnet and a wire?

A useful voltage can be obtained by moving a wire perpendicularly through a magnetic field; the electrons in the wire are pushed to one side creating a flow of electricity which is perpendicular to both the magnetic field and direction of wire motion.

6 years 40 weeks ago
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