Tag: measuring temperature

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Questions Related to measuring temperature

Multiple choice physics heat - measurement application of various thermometric scales different types of thermometers measuring temperature introduction to temperature

State whether given statement is True or False
The upper standard point of a thermometer is 273 K

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The lower fixed point, or ice point, is the temperature of pure melting ice at normal atmospheric pressure. The upper fixed point, or steam point, is the temperature of pure boiling water at normal atmospheric pressure.

Multiple choice physics heat - measurement application of various thermometric scales different types of thermometers measuring temperature introduction to temperature

A barometer with a brass scale correct at $0^oC$ reads $70\ cm$ of mercury on a day when the air temperature is $40^oC$. the correct reading at $0^oC$ is (Coefficient of real expansion of mercury, is $0.00018/^oC$ and the coefficient of linear expansion of brass is $0.000018/^oC$.

  1. $60.5\ cm$

  2. $69.5\ cm$

  3. $20.5\ cm$

  4. $50.00\ cm$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

If the correct heading of barometer at $0^oC$ is $70\ cm$ then the at $40^oC,$ the reading will show,

$L=70(1+\alpha _1\Delta T)$    $[\alpha$ ,of Brass , $\Delta T=40\ k]$
similarly , mercury expands to $70\ cm$ from initial length $Lo$
$\Rightarrow L=Lo(1+\alpha _2\Delta T)$   ($\alpha _2:$ mercury)
It gives :-
$Lo=\dfrac{70(1+\alpha _2\Delta T)}{(L+\alpha _2\Delta T)}=\dfrac{70(1+1.8\times Lo^{-5}\times 40)}{(1+1.8\times 10^{-4}\times40)}$
$Lo=69.55\ cm$

Multiple choice physics heat - measurement application of various thermometric scales different types of thermometers measuring temperature introduction to temperature

The pressure of a gass filled in the bulb of a constant volume gas thermometer at temperatures $0^{o}C$ and $100^{o}C$ are $27.50\ cm$ and $37.50\ cm$ of $Hg$ respectively. At an unknown temperature the pressure is $32.45\ cm$ of $Hg$. Unknown temperature is

  1. $30^{o}C$

  2. $39^{o}C$

  3. $49.5^{o}C$

  4. $29.6^{o}C$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Using the linear relationship for a constant volume gas thermometer, T = ((P - P0) / (P100 - P0)) * 100. Substituting values: ((32.45 - 27.50) / (37.50 - 27.50)) * 100 = (4.95 / 10) * 100 = 49.5 C.

Multiple choice physics heat - measurement application of various thermometric scales different types of thermometers measuring temperature introduction to temperature

The height of the mercures column in a barometer provided with a bross scale corrected at $ 0^0C $ is obserevd to be 74.9 cm at $ 15^0 C $ . find the true height of the coulmn at $ 0^0 C/ \alpha _b=20 \times 10^{-6} /c^0 \gamma _Hg=175 \times 10^{-6}/c^0 . $

  1. 74.72 cm

  2. 79.92 cm

  3. 74.12 cm

  4. 72.64 cm
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The brass scale expands at 15°C, making divisions larger. Apparent reading is smaller. Brass scale factor = 1 + 20×10^-6 × 15 = 1.0003. True height = 74.9 × 1.0003 = 74.8778 cm. Correcting for mercury contraction from 15°C to 0°C: final height = 74.8778 / (1 + 175×10^-6 × 15) = 74.8778 / 1.0026 = 74.72 cm.

Multiple choice physics heat - measurement application of various thermometric scales different types of thermometers measuring temperature introduction to temperature

Mercury thermometers can be used to measure temperatures upto:

  1. $100^{o}C$

  2. $212^{o}C$

  3. $360^{o}C$

  4. $500^{o}C$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Mercury thermometer is based on the principle of change of volume with rise of temperature and can measure temperatures ranging from $-{30}^{\circ}$C to ${357}^{\circ}$C.

Multiple choice physics heat - measurement application of various thermometric scales different types of thermometers measuring temperature introduction to temperature

We cannot use mercury thermometer at low temperatures because:

  1. Glass might break down at low temperature.

  2. Heat does not flow from the body whose measurement we are taking with the thermometer.

  3. At low temperatures mercury becomes transparent and it becomes difficult to take the readings.

  4. Mercury freezes at low temperatures.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Mercury, which is used as a thermometric liquid, has the following characteristic properties:

1. Mercury has a high boiling point of about $357^{\circ}$C and therefore can be used to measure temperatures as high as $357^{\circ}$C.

2. Mercury has a freezing point of about $-39^{\circ}$C and hence it is suitable in thermometers to record low temperatures (although not very low temperatures).

3. Mercury is opaque and has a shining silvery colour of its own, making it clearly visible in the capillary tube of a thermometer. 


4. Mercury needs very little heat to expand and so it can easily measure the temperature of a body without causing a decrease in the body's temperature.

5. Mercury does not stick to the side of the glass capillary tube of a thermometer. Therefore, it allows accurate temperature measurement.

6. Mercury is a good conductor of heat.

7. Mercury is relatively expensive.

Multiple choice physics heat - measurement application of various thermometric scales different types of thermometers measuring temperature introduction to temperature

Mercury is commonly used as a thermometric fluid rather than water because

  1. specific heat of mercury is less than water

  2. specific heat of mercury is more than water

  3. mercury has greater visibility than water

  4. density of mercury is more than the water
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Mercury is commonly used as a thermometric fluid rather than water because mercury has greater visibility than water
Mercury has high melting and boiling points making it a liquid over a broad range of temperature.
Since it is a metal, it has a stable coefficient of expansion hence it expands uniformly and noticeably for a slight change of temperature.
Mercury is a non sticky viscous metal and hence it makes a clear meniscus, helpful in readings.
Mercury will not expand when it solidifies hence it doesn’t break the glass tube of the thermometer.
Multiple choice physics heat - measurement application of various thermometric scales different types of thermometers measuring temperature introduction to temperature

Compared to other liquids, why is mercury preferred as a barometric fluid?

  1. Height of mercury barometer is smaller so it is more convenient to handle

  2. Mercury does not stick to the glass surface of barometric tube

  3. Mercury shines so it is easier to take the observations

  4. Coefficient of expansion of mercury is less than other liquids
Reveal answer Fill a bubble to check yourself
A,B Correct answer
Multiple choice physics heat - measurement application of various thermometric scales different types of thermometers measuring temperature introduction to temperature

A thermometer is gradated in millimeters . It registers -3 mm when the bulb of themometer is a pure melting ice  and 22 mm when the thermometer is in stem at a pressure of 1 atmosphere. The temperature in $^{ \circ  }C$  when the thermometer registers 13 mm is 

  1. $\frac { 13 }{ 25 } \times 100$

  2. $\dfrac { 16 }{ 25 } \times 100$

  3. $\dfrac { 13 }{ 22 } \times 100$

  4. $\dfrac { 16 }{ 22 } \times 100$
Reveal answer Fill a bubble to check yourself
A Correct answer