For 1. In principle, the refractive index of a true vacuum is identically 1. For air at atmospheric pressure, the index is 1.000293 for visible light. Therefore, you should be able to determine the deviations between in refractive angles for a jar filled with air and one under vacuum. Since we're talking deviations on the order of one in ten thousandth, it's be quite difficult to measure this as a demo, but it could be done in the lab. The buoyancy/weight of the container could also be used to differentiate it from one filled with air.

For 2. A lot of metals have solid room temperature vapor pressures in the ultra-high vacuum region. For instance, if you had a chunk of Cadnium of Zinc (down scroll for the charts) in your container, all you'd need to do is shine a heat lamp on the container heating the metal by a few dozen degrees Celsius and they'd begin to evaporate away. These materials have vapor pressures around 10^-8 mBar somewhere between 300 to 400 K.

One more fun way to determine the success of your vacuum process would be to watch a Crookes radiometer as you lower the pressure. As you reach below 10^-6 mBar, the rotation should stop.

For 1. In principle, the refractive index of a true vacuum is identically 1. For air at atmospheric pressure, the index is 1.000293 for visible light. Therefore, you should be able to determine the deviations between in refractive angles for a jar filled with air and one under vacuum. Since we're talking deviations on the order of one in ten thousandth, it's be quite difficult to measure this as a demo, but it could be done in the lab. The buoyancy/weight of the container could also be used to differentiate it from one filled with air.

For 2. A lot of metals have solid room temperature vapor pressures in the ultra-high vacuum region. For instance, if you had a chunk of Cadnium of Zinc (down scroll for the charts) in your container, all you'd need to do is shine a heat lamp on the container heating the metal by a few dozen degrees Celsius and they'd begin to evaporate away. These materials have vapor pressures around 10^-8 mBar somewhere between 300 to 400 K.

One more fun way to determine the success of your vacuum process would be to watch a Crookes radiometer as you lower the pressure. As you reach below 10^-6 mBar, the rotation should stop.

For 1. In principle, the refractive index of a true vacuum is identically 1. For air at atmospheric pressure, the index is 1.000293 for visible light. Therefore, you should be able to determine the deviations in refractive angles for a jar fill with air and one under vacuum. Since we're talking deviations on the order of one in ten thousandth, it's be quite difficult to measure this as a demo, but it could be done in the lab. The buoyancy/weight of the container could also be used to differentiate it from one filled with air.

For 2. A lot of metals have solid room temperature vapor pressures in the ultra-high vacuum region. For instance, if you had a chunk of Cadnium of Zinc in your container, all you'd need to do is shine a heat lamp on the container heating the metal by a few dozen degrees Celsius and they'd begin to evaporate away. These materials have vapor pressures around 10^-8 mBar somewhere between 300 to 400 K.

One more fun way to determine the success of your vacuum process would be to watch a Crookes radiometer as you lower the pressure. As you reach below 10^-6 mBar, the rotation should stop.

For 1. In principle, the refractive index of a true vacuum is identically 1. For air at atmospheric pressure, the index is 1.000293 for visible light. Therefore, you should be able to determine the deviations between in refractive angles for a jar filled with air and one under vacuum. Since we're talking deviations on the order of one in ten thousandth, it's be quite difficult to measure this as a demo, but it could be done in the lab. The buoyancy/weight of the container could also be used to differentiate it from one filled with air.

For 2. A lot of metals have solid room temperature vapor pressures in the ultra-high vacuum region. For instance, if you had a chunk of Cadnium of Zinc (down scroll for the charts) in your container, all you'd need to do is shine a heat lamp on the container heating the metal by a few dozen degrees Celsius and they'd begin to evaporate away. These materials have vapor pressures around 10^-8 mBar somewhere between 300 to 400 K.

One more fun way to determine the success of your vacuum process would be to watch a Crookes radiometer as you lower the pressure. As you reach below 10^-6 mBar, the rotation should stop.