Why is the bore of a thermometer narrower directly above the bulb?

Why is the bore of a thermometer narrower directly above the bulb?

The thermometer is made relatively small so that it is portable and cheap. The liquid is contained in a thin-walled glass bulb. The bulb is made relatively larger than its bore to contain more of the liquid, so as to improve sensitivity. The narrow bore of the capillary tube is uniform.

Why is there a small constriction in the capillary tube just above the bulb in the clinical thermometer?

This thermometer has markings from 35°c to 43°c. It has a slight bend or kink in the stem just above the bulb, this kink is called the constriction which prevents the mercury from falling back all by itself.

What is the bore of a thermometer?

The Stem and Capillary Bore Magnified glass makes up the outside jacket of the thermometer, which is called the stem. A thin bore inside the stem gives mercury a route of travel as it expands and contracts. The thin bore is called a capillary. Magnified glass makes reading the mercury level easier.

How does a larger bulb increase sensitivity?

So with a larger bulb, the mercury would expand further up the capillary with the same change in temperature. In this sense, yes, the bigger bulb would make the range increase.

Why should the bore of a thermometer tube be uniform?

Does a clinical thermometer have a large bore?

thermometer, instrument for measuring temperature. The clinical thermometer is a small tubular instrument of rather thick glass. It consists essentially of a small vacuum tube of uniform bore closed at one end and connected at the other with a mercury chamber (either a bulb or a short tube of larger bore).

Why there is a slight bend in the bore near the bulb?

A slight bend or kink in the capillary tube of the clinical thermometer near the bulb ensures that the mercury does not move back into the bulb when the thermometer is taken out of a person’s mouth for reading.

Which type of thermometer has a constriction narrowed passage in the bore of the glass tube?

One special kind of mercury-in-glass thermometer, called a maximum thermometer, works by having a constriction in the neck close to the bulb.

How does Bulb size affect thermometer sensitivity?

Sensitivity vs Range How much of a small change in temperature is observable by the thermometer….for the same bulb size, a narrower capillary tube would be more sensitive than a broad one.

How does Bulb size affect thermometer?

Using a thermometer with a smaller bulb – A smaller bulb contains less mercury and therefore absorbs heat in a shorter moment in time. A glass bulb with thinner wall – Heat can be transferred to the bulb straightforwardly.

At what temperature is the Celsius and Kelvin scale equal?

0 degrees Celsius is equal to 273.15 Kelvins. The basic formula is °C + 273.15 = K.

Why do you need a smaller bulb for a thermometer?

So, if by ‘range’, you mean the range of temperatures accessible by a fixed length of tube, then you would want a smaller bulb so that the liquid wouldn’t rise as high as fast. I hope that all makes sense. Let me know if some part doesn’t, and I (or someone else), can try and clarify. Hi!

Why does a thermometer have a fixed range?

But then you have to think about what you mean by ‘range’. The liquid will go further up the tube for the same temperature, but this actually means that, if you have a fixed tube-length, you will not be able to record as high of temperatures, because the same temperature will now make the fluid rise higher.

Why does a thermometer not record the same temperature?

The liquid will go further up the tube for the same temperature, but this actually means that, if you have a fixed tube-length, you will not be able to record as high of temperatures, because the same temperature will now make the fluid rise higher. For a concrete example, let’s say that you have a thermometer that tops out at 100 C.

How does a change in temperature affect the size of a bulb?

But suppose there is a large bulb containing 99% of the mercury and the tube only holds 1%. Now a 1% increase in temperature again gives a 1%increase in volume but this doubles the amount in the tube and so gives a change in the height of 100% not 1%.