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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.

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6 years 5 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.

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6 years 24 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.

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6 years 31 weeks ago

Transformers

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.

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6 years 35 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.

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6 years 36 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.

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6 years 36 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.

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6 years 36 weeks ago

Cool Roofs

Keywords: albedo, carbon dioxide, emission, energy, surface temperature

Can painting our roofs white offset tonnes of CO2 emissions??

In this article, we look at how we can save energy, reduce the Earth’s surface temperature and offset carbon dioxide emissions just by making our roofs and pavements a lighter colour!

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6 years 36 weeks ago

Electric Shock

Keywords: current, electric shock, electrical safety, electricity, electromagnetic induction, GFCI, ground fault circuit interrupter, induced emf, magnetic field, magnetic flux, protective devices, resistance, voltage

What effect does electricity have on the human body?

This article discusses the physiological effects of electric shock as well as a protective device installed in typically dangerous areas: ground fault circuit interrupters.

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6 years 37 weeks ago

Bottle Rockets

Keywords: air, bottle, force, fuel, pressure, rocket, thrust, water

Bottle Rockets - a future mode of transport?

This article explores the physics behind bottle rockets and how they work. It also discusses whether or not bottle rockets would be a viable means of transport.

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6 years 37 weeks ago
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