Corona Virus: How Are We Doing?

You have the virus

  • Yes

    Votes: 57 21.2%

  • I've been quaranteened

    Votes: 19 7.1%

  • I personally know someone who has been diagnosed

    Votes: 71 26.4%

  • Clear as far as I know

    Votes: 150 55.8%
  • Total voters
    269
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steve292

steve292

Guru
Location
Weston-super-mare, north somerset
Joey Shabadoo said:
Smelt the tin until molten (the tin will boil off at around 230 C but you need to get your kiln up to about 1370 C for the steel. Once molten, slowly pour the liquid steel into a large pail of water from a height of about 1.5m. The molten steel will form balls as it hits the water - adjust your flowrate to get your balls the right size. Fish the steel balls out from the bottom of the pail, paint them green and voila - peas with as much taste and nutritional value as the pie itself.
Click to expand...
You are a bottomless source of material to me..
 
Spiderweb

Spiderweb

Not So Special One
Location
North Yorkshire
The Germans have been putting their beach towels on hospital beds :eek:
 
Joey Shabadoo

Joey Shabadoo

My pronouns are "He", "Him" and "buggerlugs"
C R said:
Yes please, something fun to do with the children when schools close.
Click to expand...

ok


The speed of light is, as everyone knows, 186,000 miles per second or 299,792km per second. That's pretty fast. However, that's the speed when light travels in a vacuum; in air, it slows down to 299,552km per second which doesn't sound quite as fast. A London bus travelling at the speed of light could travel from London to New York and back twenty five times in one second. But, how could you prove that? And how could you prove that in your kitchen? For this experiment you will need:

  • A microwave oven
  • A plate
  • Some cheese
  • A cheese grater
  • A ruler
Please ask an adult to help, as microwave ovens can be dangerous.

Grate enough cheese to cover the plate to a depth of about 5mm. Take the glass turntable and any roller mechanism out of the microwave and put the plate of cheese in. Turn the heat to full power for 20 seconds. When you take the plate out, you will see two lines of melted cheese.

The reason for this is the oven has a microwave emitter in the side which sends out energy as a wave - the same sort of wave as a radio wave or a light wave. This wave is perfectly even and regular. Imagine a line on a graph that curves up to a peak then down to a trough. Where the wave is at its highest and lowest points, it is reinforced by the waves that are bouncing around inside the oven so that two hot spots are created a half-wavelength apart.

Most microwaves have a stationary emitter and the food is revolved on a turntable to rotate it evenly through the hotspots. This is why it is impossible to microwave an ant. If you put an ant into a microwave and watch through the window when you switch it on, you will see the ant scurrying around on the turntable. Whenever the table rotates through a hot spot, the ant simply runs away from the heat to a cooler area. Some microwave ovens have a rotating emitter. The plate in these ovens stands still and the hot spots move. If your microwave doesn't have a turntable, it won't be possible to do this experiment unless you can train some ants to carry the plate on their backs and run at a constant speed in front of the hotspots.

Where the cheese has melted is where the wave was at its highest and lowest spots. Wavelength is the distance between two peaks so by measuring the distance between these two lines of melted cheese we can find half the wavelength.

It may be difficult to find the exact centre of the lines in the melted cheese, but try to be as exact as you can. In the CycleChat kitchen, the distance was found to be 60mm. Multiplying this by 2 gives us the wavelength: in this case, 120mm.

We now know how long the wave was, but we need to know how many waves there are per second. On the back of the oven will be a label that tells you the frequency the oven operates at. On the CycleChat microwave it was 2450MHz, or 2450 million waves per second.

So, 2,450,000,000 cycles per second
120mm = 0.00012km
In 1 second, the wave travels 2,450,000,000 x 0.00012km = 294,000km

This tells us that the speed of light is 294,000km per second: quite close to the actual figure of 299,552km per second, within 2% anyway. When you consider how difficult it was to measure the lines of melted cheese, this is pretty much spot on.

Congratulations. You have just calculated the speed of light in your kitchen1.

Now wash your hands


from https://h2g2.com/edited_entry/A32873493 where I wrote it a few years ago
 
C R

C R

Guru
Location
Worcester
Joey Shabadoo said:
ok


The speed of light is, as everyone knows, 186,000 miles per second or 299,792km per second. That's pretty fast. However, that's the speed when light travels in a vacuum; in air, it slows down to 299,552km per second which doesn't sound quite as fast. A London bus travelling at the speed of light could travel from London to New York and back twenty five times in one second. But, how could you prove that? And how could you prove that in your kitchen? For this experiment you will need:

  • A microwave oven
  • A plate
  • Some cheese
  • A cheese grater
  • A ruler
Please ask an adult to help, as microwave ovens can be dangerous.

Grate enough cheese to cover the plate to a depth of about 5mm. Take the glass turntable and any roller mechanism out of the microwave and put the plate of cheese in. Turn the heat to full power for 20 seconds. When you take the plate out, you will see two lines of melted cheese.

The reason for this is the oven has a microwave emitter in the side which sends out energy as a wave - the same sort of wave as a radio wave or a light wave. This wave is perfectly even and regular. Imagine a line on a graph that curves up to a peak then down to a trough. Where the wave is at its highest and lowest points, it is reinforced by the waves that are bouncing around inside the oven so that two hot spots are created a half-wavelength apart.

Most microwaves have a stationary emitter and the food is revolved on a turntable to rotate it evenly through the hotspots. This is why it is impossible to microwave an ant. If you put an ant into a microwave and watch through the window when you switch it on, you will see the ant scurrying around on the turntable. Whenever the table rotates through a hot spot, the ant simply runs away from the heat to a cooler area. Some microwave ovens have a rotating emitter. The plate in these ovens stands still and the hot spots move. If your microwave doesn't have a turntable, it won't be possible to do this experiment unless you can train some ants to carry the plate on their backs and run at a constant speed in front of the hotspots.

Where the cheese has melted is where the wave was at its highest and lowest spots. Wavelength is the distance between two peaks so by measuring the distance between these two lines of melted cheese we can find half the wavelength.

It may be difficult to find the exact centre of the lines in the melted cheese, but try to be as exact as you can. In the CycleChat kitchen, the distance was found to be 60mm. Multiplying this by 2 gives us the wavelength: in this case, 120mm.

We now know how long the wave was, but we need to know how many waves there are per second. On the back of the oven will be a label that tells you the frequency the oven operates at. On the CycleChat microwave it was 2450MHz, or 2450 million waves per second.

So, 2,450,000,000 cycles per second
120mm = 0.00012km
In 1 second, the wave travels 2,450,000,000 x 0.00012km = 294,000km

This tells us that the speed of light is 294,000km per second: quite close to the actual figure of 299,552km per second, within 2% anyway. When you consider how difficult it was to measure the lines of melted cheese, this is pretty much spot on.

Congratulations. You have just calculated the speed of light in your kitchen1.

Now wash your hands


from https://h2g2.com/edited_entry/A32873493 where I wrote it a few years ago
Click to expand...
Brilliant, I can fill a whole day with that and explaining standing waves, thank you.
 
newfhouse

newfhouse

Resolutely on topic
Joey Shabadoo said:
ok


The speed of light is, as everyone knows, 186,000 miles per second or 299,792km per second. That's pretty fast. However, that's the speed when light travels in a vacuum; in air, it slows down to 299,552km per second which doesn't sound quite as fast. A London bus travelling at the speed of light could travel from London to New York and back twenty five times in one second. But, how could you prove that? And how could you prove that in your kitchen? For this experiment you will need:

  • A microwave oven
  • A plate
  • Some cheese
  • A cheese grater
  • A ruler
Please ask an adult to help, as microwave ovens can be dangerous.

Grate enough cheese to cover the plate to a depth of about 5mm. Take the glass turntable and any roller mechanism out of the microwave and put the plate of cheese in. Turn the heat to full power for 20 seconds. When you take the plate out, you will see two lines of melted cheese.

The reason for this is the oven has a microwave emitter in the side which sends out energy as a wave - the same sort of wave as a radio wave or a light wave. This wave is perfectly even and regular. Imagine a line on a graph that curves up to a peak then down to a trough. Where the wave is at its highest and lowest points, it is reinforced by the waves that are bouncing around inside the oven so that two hot spots are created a half-wavelength apart.

Most microwaves have a stationary emitter and the food is revolved on a turntable to rotate it evenly through the hotspots. This is why it is impossible to microwave an ant. If you put an ant into a microwave and watch through the window when you switch it on, you will see the ant scurrying around on the turntable. Whenever the table rotates through a hot spot, the ant simply runs away from the heat to a cooler area. Some microwave ovens have a rotating emitter. The plate in these ovens stands still and the hot spots move. If your microwave doesn't have a turntable, it won't be possible to do this experiment unless you can train some ants to carry the plate on their backs and run at a constant speed in front of the hotspots.

Where the cheese has melted is where the wave was at its highest and lowest spots. Wavelength is the distance between two peaks so by measuring the distance between these two lines of melted cheese we can find half the wavelength.

It may be difficult to find the exact centre of the lines in the melted cheese, but try to be as exact as you can. In the CycleChat kitchen, the distance was found to be 60mm. Multiplying this by 2 gives us the wavelength: in this case, 120mm.

We now know how long the wave was, but we need to know how many waves there are per second. On the back of the oven will be a label that tells you the frequency the oven operates at. On the CycleChat microwave it was 2450MHz, or 2450 million waves per second.

So, 2,450,000,000 cycles per second
120mm = 0.00012km
In 1 second, the wave travels 2,450,000,000 x 0.00012km = 294,000km

This tells us that the speed of light is 294,000km per second: quite close to the actual figure of 299,552km per second, within 2% anyway. When you consider how difficult it was to measure the lines of melted cheese, this is pretty much spot on.

Congratulations. You have just calculated the speed of light in your kitchen1.

Now wash your hands


from https://h2g2.com/edited_entry/A32873493 where I wrote it a few years ago
Click to expand...
Genius. Somehow I’m going to use this as the basis of a board question the next time we interview for someone with RF skills.
 
glasgowcyclist

glasgowcyclist

Charming but somewhat feckless
Location
Scotland
Joey Shabadoo said:
This is why it is impossible to microwave an ant. If you put an ant into a microwave and watch through the window when you switch it on, you will see the ant scurrying around on the turntable. Whenever the table rotates through a hot spot, the ant simply runs away from the heat to a cooler area.
Click to expand...

I can see plenty of children skipping the cheese/speed of light part and desperately trying to microwave ants instead.
 
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