⢠the surface of a liquid acts as if it is under tension, and this tension ...
⢠the surface of a liquid acts as if it is under tension, and this tension ...
⢠the surface of a liquid acts as if it is under tension, and this tension ...
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Surface Tension<br />
• <strong>the</strong> <strong>surface</strong> <strong>of</strong> a <strong>liquid</strong> <strong>acts</strong> <strong>as</strong> <strong>if</strong> <strong>it</strong> <strong>is</strong> <strong>under</strong><br />
<strong>tension</strong>, <strong>and</strong> th<strong>is</strong> <strong>tension</strong>, acting parallel to<br />
<strong>the</strong> <strong>surface</strong>, ar<strong>is</strong>es from <strong>the</strong> attractive<br />
forces between <strong>the</strong> molecules<br />
• ϒ = F / L<br />
• ϒ: <strong>surface</strong> <strong>tension</strong>; F / L: force per un<strong>it</strong><br />
length that <strong>acts</strong> across any line in a<br />
<strong>surface</strong>, tending to pull <strong>the</strong> <strong>surface</strong> closed<br />
Friday, 22 January 2010
Surface Tension<br />
• ϒ = F / 2L<br />
• film h<strong>as</strong> top <strong>and</strong><br />
bottom <strong>surface</strong>;<br />
so length being<br />
incre<strong>as</strong>ed <strong>is</strong> 2L<br />
Friday, 22 January 2010
Cohesive <strong>and</strong> Adhesive<br />
Forces<br />
• cohesive: between<br />
molecules <strong>of</strong> <strong>the</strong> same<br />
type<br />
• adhesive: between<br />
molecules <strong>of</strong> d<strong>if</strong>ferent<br />
types<br />
Friday, 22 January 2010
Capillar<strong>it</strong>y<br />
• in tubes having very<br />
small diameters,<br />
<strong>liquid</strong>s r<strong>is</strong>e or fall<br />
relative to <strong>the</strong> level <strong>of</strong><br />
<strong>the</strong> surrounding <strong>liquid</strong><br />
• depends on relative<br />
strengths <strong>of</strong> adhesive<br />
<strong>and</strong> cohesive forces<br />
Friday, 22 January 2010
Friday, 22 January 2010
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