Mercury boils at 367° C. However, mercury thermometers are made such that they can measure temperature upto 500°C. This is done by
maintaining vacuum above mercury column in the stem of the thermometer.
filling nitrogen gas at high pressure above the mercury column.
filling oxygen gas at a high pressure above mercury column.
filling nitrogen gas at a low pressure above the mercury column.
Two identical glass spheres filled with air are connected by a horizontal glass tube. The glass tube contains a pellet of mercury at its mid-point. Air in one sphere is at 0°C and the other is at 20°C. If both the vessels are heated through 10°C, then neglecting the expansions of the bulbs and the tube.
the mercury pellet gets displaced towards the sphere at a lower temperature.
The mercury pellet gets displaced towards the sphere at a higher temperature
The mercury pellet does not get displaced at all.
the temperature rise causes the pellet to expand with any displacement.
C.
The mercury pellet does not get displaced at all.
Let n1 and n2 be the number of moles in the bulbs at 0°C and 20°C, respectively, then,
pV = 273n1R = 293n2R
when the vessels are heated, let the volume of low temperature be V1 and that of the other be V2. Since pressure are same, hence
V1p = 283 n1R and V2p = 303 n2R
From Eqs. (i) and (ii), we get
Thus, the mercury pellet remains at the same position.
Water rises in a capillary upto a extension height such that upward force of surface tension balances the force of 75 x 10-4 N due to weight of water. If surface tension of water is 6x10-2 N/m.The internal circumference of the capillary must be
12.5m
6.5m
0.50m
1.25m
A capillary tube of radius r can support a liquid of weight 6.28 x 10-4 N. If the surface tension of the liquid is 5 x 10-2N/m. The radius of capillary must be
m
1.5
The soap bubbles have radii in the ratio 2: 1 ratio of excess pressure in side there is
1:4
4:1
2:1
1:2
The radius R of the soap bubble is doubled under isothermal condition. If T be the surface tension of soap bubble. The work done in doing so is given by
An ice-cube of density 900 kg /m3 is floating in water of density 1000 kg / m3. The percentage of volume of ice-cube outside the water is
20%
35%
10%
25%
A tank is filled with water upto height H. When a hole is made at a distance h below the level of water. What will be the horizontal range of water jet?
A charged oil drop is suspended in uniform field of 3 x 104 V/m so that it neither falls nor rises. The charge on the drop will be (Take the mass of the charge = 9.9 x 10-15 kg and g = 10 m/s2 )
3.3 × 10-18 C
3.2 × 10-18 C
1.6 × 10-18 C
4.8 × 10-18 C
A frame made of metallic wire enclosing a surface area A is covered with a soap film. If the area of the frame of metallic wire is reduced by 50%, the energy of the soap film will be changed by
100%
75%
50%
25%