加载中…奇趣物理实验——登堂入室
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文献1中提到
沸腾球早期被用作温差计
随后
发展出了所谓的爱情温度计
love meter
A screen is placed between Leslie
cube (A) and differential thermometer (D) as in Fig. 14.7. The
screen has a small hole. A reflective surface (B) is placed between
the screen and the differential thermometer. Radiation from the
cube passes through the hole, reflects on the surface and directs
toward the differential thermometer. A suitable position of the
thermometer is sought for one bulb to be heated by the reflected
radiation. It can then be confirmed that the CBD and CBA levels
coincide and that the angle of incidence is equal to the
reflectance angle.
The Leslie cube is positioned
opposite a parabolic mirror and at a fairly large distance to the
focal length of the mirror, which has the property of concentrating
the parallel beams on its surface (Fig. 14.8). A small flat piece
of some material is placed at a very short distance before the
focus and in such a way that the radiation is reflected and
directed to one of the bulbs of the differential thermometer.
Comparing the temperature values for surfaces of different
materials gives a measure of the reflectivity of these materials
for infrared radiation.
The Leslie cube is positioned
opposite a parabolic mirror and at a fairly long distance with
respect to the focal length of the mirror, which has the property
of focusing the parallel rays hitting it. One bulb of the
differential thermometer is placed in the focus. Then we turn
different sides of Leslie cube to the mirror and record the
temperature values on the thermometer. The material to which the
highest temperature corresponds is the one with the highest thermal
radiation emission factor. It is reported that the coefficient
decreases with the alternation of the surfaces as follows: black,
paper-covered, glass-covered, and tin.
Differential thermometers were used
in the study of heat and heat radiation during the first decades of
the nineteenth century. The invention of the thermopile (Fig. 14.9)
by the Italian physicist Leopoldo Nobili in 1829 and the adoption
of it in the Melloni optical bench in 1835 gave scientists a more
accurate and handy instrument. After 1841, when theMelloni bench
was commercialized, it gradually pushed the differential
thermometers to themargins of research because it lacked one of
their main disadvantages; the fact that the glass of the bulbs
absorbed radiant heat. The Melloni bench was used until around 1880
when in turn it was replaced by the bolometer. As a popular physics
textbook explained in 1877: “The instrument (differential
thermometer) is now only used as a thermoscope; that is, to
indicate a difference of temperature between the two bulbs, and not
to measure its amount”.
A modern variation of the Franklin
pulse glass, which is a particularly interesting toy, is the
so-called hand boiler or love meter (Fig. 14.12). In fact it is
just a lightly restructured pulse glass. The tube is vertical but
usually not straight as it includes some curves for aesthetic
purposes and it descends almost to the bottom of the lower bulb,
immersed in the liquid.
Nowadays the liquid used in the toy
is notwater, as in the pulse glass, butmethanol. This is because
the liquid must have a low boiling point but also be safe. For the
latter reason diethyl ether–the theoretically best choice–has never
been used and the methyl chloride (dichloromethane) is not used any
more, because it is considered to be toxic (OSHA site).
If we put the lower bulb into our
palm, then the liquid evaporates rapidly and the vapor pressure
increases. As a result the liquid rises through the tube into the
upper bulb, given that there is quite a large temperature
differential between the two bulbs. As soon as the whole liquid
rises, a quantity of its vapors comes up and ends up in the upper
bulb creating a strong turbulence resembling boiling.
Compared to the pulse glass, the
hand boiler has two advantages. It can stand upright alone and it
has an even greater degree of surprise because the liquid not only
moves from one bulb to another, but at the same time defies
gravity.
A modern variation of the Franklin
pulse glass, which is a particularly interesting toy, is the
so-called hand boiler or love meter (Fig. 14.12). In fact it is
just a lightly restructured pulse glass. The tube is vertical but
usually not straight as it includes some curves for aesthetic
purposes and it descends almost to the bottom of the lower bulb,
immersed in the liquid.
Nowadays the liquid used in the toy
is notwater, as in the pulse glass, butmethanol This is because the
liquid must have a low boiling point but also be safe. For the
latter reason diethyl ether–the theoretically best choice–has never
been used and the methyl chloride (dichloromethane) is not used any
more, because it is considered to be toxic (OSHA site).
If we put the lower bulb into our
palm, then the liquid evaporates rapidly and the vapor pressure
increases. As a result the liquid rises through the tube into the
upper bulb, given that there is quite a large temperature
differential between the two bulbs. As soon as the whole liquid
rises, a quantity of its vapors comes up and ends up in the upper
bulb creating a strong turbulence resembling boiling.
Compared to the pulse glass, the
hand boiler has two advantages. It can stand upright alone and it
has an even greater degree of surprise because the liquid not only
moves from one bulb to another, but at the same time defies
gravity.
沸腾球内所装液体
文献中有多种报道
文献1：Its interior is filled about 1/3
to 1/2 with a quantity of a volatile liquid such as an alcohol乙醇or
ether乙醚. Nowadays the liquid used in the toy is notwater, as in the
pulse glass, but methanol甲醇. This is because the liquid must have a
low boiling point but also be safe. For the latter reason diethyl
ether乙醚–the theoretically best choice–has never been used and the
methyl chloride氯甲烷(dichloromethane) is not used any more, because
it is considered to be toxic (OSHA site).
文献2：The Drinking Bird is filled with
methylene chloride二氯甲烷or a freon二氯二氟代甲烷.
文献3：Drinking Birds:In Franklin’s
case the liquid inside was purportedly water, but in my palm glass,
I have verified by density and boiling point that it is ethanol乙醇.
Hand “Boiler”: the liquid—ethanol乙醇 containing.
沸腾球外包装：Contains : Ethyl
Alcohol乙醇
网上可以找到
多种外形的
爱情温度计
从左至右分别为
正常速度、1/8和1/64倍速
从最右侧图片中看到
液面上升至顶端玻璃球底部时
没有出现喷射的液柱
液面上升时
出现了明显的液柱喷射
这是因为
在直管的端口
管径突然收缩
导致流速增大
紫色液体的容器结构
和红色、蓝色不同
它有两个小孔
都会发生液体喷射
随后液体通过下方小孔
流回容器底部
如果只有最上方的一个孔
液体进入上部空间后
将无法回流
从最右侧的热像仪画面中
可以看到
下方玻璃容器的外壁快速升温
但上方的升温非常缓慢
这间接说明了
液体本身的温度变化不大
液体的喷射
是气体升温、膨胀导致的
而不是液体沸腾
这是上次拍摄的
倾倒冷水时的
沸腾球
与沸腾球相比
本次的爱情温度计
在倾倒冷水时的表现
并不精彩
没有出现喷射的液柱
这有三方面的原因
一是：液面高度上升
流速降低
二是：直管端口没有收缩
三是：冷水从至下流过
上方和下方气体都在降温
有兴趣的读者，可以参阅如下文献，进行深入了解
1：Biographies in the History of
Physics. Springer International Publishing, 2020.
2：Toys in the classroomJ ournal of
Chemical Education, 2005, 82(10):1450.
3：The hand boiler and how it does
not work. The Physics Teacher 60.3 (2022): 234-235.
4：“富蘭克林沸腾球”的几个实验, 《物理通报》1956,12,
760.
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