Question

43. The height of the mercury column in a
barometer provided with a brass scale
corrected at 0°C is observed to be 74.9 cm
at 15°C. Find the true height of the column
at 15°C.
[Abrass = 20 x 10-6°C; YHg = 175 x 106/°C]​

Answer 1

Answer:

The height of the mercury column in a

barometer provided with a brass scale

corrected at 0°C is observed to be 74.9 cm

at 15°C. Find the true height of the column

at 15°C.

Explanation:

Here,

ht = 74.9 cm

α = 20 x 10-6°C

t = 15°C.

Height of the mercury column depends upon atmospheric pressure

But as the reading is taken  at 15°C. there will be some error due to thermal expansion of Hg at this temperature.

So the correct height ho will be given for the same pressure at 0 °C

ht = ho(1 + αt)

74.9  = ho(1 + 20 x 10-6* 15)

=> ho = 74.9/1.0003

=> ho = 74.87 cm