Tag: physics

Questions Related to physics

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

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

  1. $30^{o}C$

  2. $39^{o}C$

  3. $49.5^{o}C$

  4. $29.6^{o}C$

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Correct Option: C

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 . $

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

  1. 74.72 cm

  2. 79.92 cm

  3. 74.12 cm

  4. 72.64 cm

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Correct Option: A

Mercury thermometers can be used to measure temperatures upto:

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

  1. $100^{o}C$

  2. $212^{o}C$

  3. $360^{o}C$

  4. $500^{o}C$

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Correct Option: C
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.

We cannot use mercury thermometer at low temperatures because:

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

  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.

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Correct Option: D
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.

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

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

  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

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Correct Option: C
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.

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

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

  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

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Correct Option: A,B

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 

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

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

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

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

  4. $\dfrac { 16 }{ 22 } \times 100$

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Correct Option: A

Release valve is seen in :

physics fluid pressure examples of hydraulic press applications of pascal's law pascal's law and its applications

  1. Hydraulic brakes

  2. Hydraulic jack

  3. Hydraulic press

  4. All

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Correct Option: C
Explanation:

In the construction of hydraulic press,release valve and press foot valves are there.hydraulic press consist of a pump tube connected with a press tube. The lower end of the pump tube is connected with a smaller tube which is further connected with an underground water tank. At the junction of the pump tube and the smaller tube is fitted a "pump foot valve" which opens in the upward direction only.

Which of the following consists of a master cylinder filled with a thick oil :

physics fluid pressure examples of hydraulic press applications of pascal's law pascal's law and its applications

  1. Hydraulic brakes

  2. Hydraulic jack

  3. Hydraulic press

  4. All

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Correct Option: A
Explanation:

A hydraulic brake essentially consist of a master cylinder which is filled with a thick oil,commonly called brake oil.

Pascal's law is used for the working of:

physics fluid pressure examples of hydraulic press applications of pascal's law pascal's law and its applications

  1. Hydraulic brakes

  2. Hydraulic jack

  3. Hydraulic press

  4. All

Show answer
Correct Option: D
Explanation:

Pascal's law is used on all the three.according to pascal's law, whenever any pressure is applied to any party of the boundary of a confined fluid,it is transmitted equally in all directions irrespective of the area on which it acts,and always acts at right angles to the surface of containing vessel.