what is linear expansion
hw to find circumference of a pencil using a thread
does widening the barometer change the pressure of liquid
Lastly in ppr 6 dey always have this triangle and tell to draw hw it will appear on the screen how do we knw wat size or if inverted or upright 
answer dem asap thx
Linear Expansion - (The increase of a planar dimension, measured by the linear elongation of a sample in the form of a beam which is exposed to two given temperatures)
When length of a solid (rod) is much greater than its breadth and thickness, linear expansion or expansion in length is considered.
Length of a rod
Length of a rod increases on heating
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About barometer.. I think since pressure is force per unit area, it doesn't matter how wide the tube is, as long as its diameter is constant.
pz
-MaNi
