Tag: physics

Quizzes (598) Questions (13441)

Questions Related to physics

Multiple choice various types of barometer fluids physics
Which of the following is not a property of mercury?

  1. It is the densest liquid known.

  2. It can be easily obtained in pure form.

  3. By using it the sides of the tube does not get wet.

  4. None
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

All the given properties of mercury shown are true.

Due to highest density, the same pressure can be measured using relatively shorter column of mercury.
Mercury can easily be obtained in pure form. Hence one can record the true atmospheric pressure as the pressure is directly proportional to the density of the liquid.

Multiple choice various types of barometer fluids physics

Vapour pressure of mercury is

  1. highest among all liquids

  2. negligible

  3. infinity

  4. None
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The vapor pressure of mercury is negligible. Thus the barometric height of a simple barometer or a mercury barometer is not affected.

Multiple choice various types of barometer fluids physics

An aluminum can of cylindrical shape contains $V _{0}\ cm^{3}$ of water. The area of the linear cross-section of the can is $A _{0}\ cm^{2}$. (All measurement refer to $T _{0}^\circ C$). Find the rise in the water level, if the temperature increases to $T _{1}C(T _{1}^\circ C > T _{0}$) $\alpha _{Al}$ and $\gamma _{water}$ are given

  1. $\dfrac { { V } _{ 0 }\left( { T } _{ 1 }-{ T } _{ 0 } \right) \left( { \gamma } _{ w }-2{ \alpha } _{ Al } \right) }{ { A } _{ 0 } } $
  2. $\dfrac { { V } _{ 0 }\left( { T } _{ 1 }-{ T } _{ 0 } \right) \left( { \gamma } _{ w }-2{ \alpha } _{ Al } \right) }{ {2A } _{ 0 } } $
  3. $\dfrac { { V } _{ 0 }\left( { T } _{ 1 }-{ T } _{ 0 } \right) \left( { \gamma } _{ w }-2{ 3\alpha } _{ Al } \right) }{ { A } _{ 0 } } $
  4. $\dfrac { { V } _{ 0 }\left( { T } _{ 1 }-{ T } _{ 0 } \right) \left( { \gamma } _{ w }-2{ 3\alpha } _{ Al } \right) }{ { 2A } _{ 0 } } $
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The volume of water at T1 is V1 = V0(1 + gamma_w * dT). The area of the can at T1 is A1 = A0(1 + 2 * alpha_Al * dT). The new height h1 = V1 / A1. The rise in level is h1 - h0 = (V0/A0) * [(1 + gamma_w * dT) / (1 + 2 * alpha_Al * dT) - 1]. Using binomial approximation (1+x)^-1 approx 1-x, this simplifies to (V0/A0) * dT * (gamma_w - 2 * alpha_Al).

Multiple choice various types of barometer fluids physics
Mercury can be obtained in its pure form. What is its advantage?

  1. True atmospheric pressure can be recorded.

  2. Mercury does not affect the barometric height.

  3. It is easily seen while taking observation.

  4. All the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Mercury can be easily obtained in its pure state and one can record the true atmospheric pressure as the pressure is directly proportional to the density of the liquid.
Multiple choice various types of barometer fluids physics

If the compressibility of water is $\sigma$ per unit atmospheric pressure, then the decrease in volume $V$ due to atmospheric pressure $p$ will be

  1. $\sigma p/V$
  2. $\sigma pV$
  3. $\sigma /pV$
  4. $\sigma V/p$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Compressibility sigma = -(1/V) * (dV/dp). Therefore, dV = -sigma * V * dp. For a pressure change p, the magnitude of volume decrease is sigma * V * p.

Multiple choice various types of barometer fluids physics

A faulty barometer shows 72cm and the air column is 10cm when the true pressure is 76cm of Hg. The barometer reading will be, when the length of air column is 5cm.

  1. 76cm of Hg

  2. 71.5 Hg

  3. 68gm of Hg

  4. 72.5gm of Hg
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Using Boyle's Law (P1V1 = P2V2) for the trapped air: (76-72) * 10 = (76-x) * 5. Thus, 4 * 10 = (76-x) * 5, so 8 = 76-x, which means x = 68 cm.

Multiple choice various types of barometer fluids physics

In the bottom of a vessel with mercury of density $\rho$ there is a round hole of radius $r$. At what maximum height of the mercury layer will the liquid still not flow out through this hole. (Surface tension = $T$) 

  1. $\dfrac T {rpg}$
  2. $\dfrac T {2rpg}$
  3. $\dfrac {2T} {rpg}$
  4. $\dfrac{4T} {rpg}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Given,


$r=$ radius of the hole


$p=$ density of mercury liquid

$g=$ acceleration due to gravity

$T=$ Surface tension

$h=$ maximum height

The liquid can not penetrate until the hydro-static pressure is greater than excess pressure.

Limiting condition,

$pgh=\dfrac{2T}{r}$

$h=\dfrac{2T}{rpg}$

The correct option is C.

Multiple choice various types of barometer fluids physics

The height of a mercury barometer is 75 cm at sea level and 50 cm at the top of a hill. Ratio of density of mercury to that of air  is $10 ^ { 4 }$ The height of the hill is

  1. 250 m

  2. 2.5 km

  3. 1 .25 km

  4. 750 m
Reveal answer Fill a bubble to check yourself
C Correct answer
Multiple choice various types of barometer fluids physics

The brass scale of a barometer gives correct reading at $10^{ o }C$. The barometer reads 75 cm at $30^{ o }C$. What is the atmospheric pressure at $8^{ o }C$(in cm Hg)

  1. 74.8

  2. 75.03

  3. 70

  4. 60
Reveal answer Fill a bubble to check yourself
C Correct answer
Multiple choice various types of barometer fluids physics

The lengths of air column are 10 and 8 cm in a faulty barometer when it shows 72 and 71 cm. The atmospheric pressure is 

  1. 76 cm of Hg

  2. 75 cm of Hg

  3. 64.4 cm of Hg

  4. None
Reveal answer Fill a bubble to check yourself
C Correct answer