# MHT-CET Physics Crash Course “Capillary Action” Class 12

## “Capillary Action” MHT-CET Class 12 Physics Crash Course | Chapter Mechanical Properties of Fluids

In this session G.S. Khairnar discussed the theory and MCQ’s of “Capillary Action”. The session will be useful for all the aspirants of MHT-CET 2022. The session will be in Marathi and English.

### Capillary Action:-

Dear aspirants in this article we are going to discuss the capillary and capillary action. Before proceeding with the article consider the following questions,

1. Sap reaches to every topmost branch and leaf of tree. How?
2. After some heavy work, we get sweated, how water from body comes out?
3. Filter paper can soak the water easily. How?

Explanation of all the above cases can be explained with the study of concept of capillary action

Let’s discuss the concept of Capillary action.……………!

A tube having a very small bore is called a capillary tube r capillary.

Capillarity action or capillarity:-

“The rise or fall of a liquid inside a capillary tube is called capillarity.”

Consider the liquid is filled in beaker and capillary is dipped vertically in liquid so as to level of liquid inside capillary rises or falls. Imagine four points A, B, C and D as shown in fig. below,

Point A: just above the liquid surface in capillary.

Point B: just below the liquid inside capillary.

Point C: just above liquid surface and outside capillary

Point D: just below liquid surface outside the capillary tube.

Let PA, PB, PC And PD be the corresponding pressures at points A, B , C and D respectively.

As liquid level inside capillary is concave,

PA> PB…………(1)

Liquid surface near points C and D is plane,

PC = PD………….(2)

As points C and D are at same horizontal level,

PA = P…………(3)

Thus from equations (2)  and (3) we have,

PD = PB …………(4)

ThereforePD > PB  i.e. the pressure at point d is greater than point B. As we know that the liquid always flows from higher pressure to lower pressure, hence the liquid level inside capillary increases up to pressure inside the capillary equals outside pressure.

### Let’s attempt the following MCQ’s………….!

Q.1) If the pressure outside free surface of liquid is greater than that of pressure inside the free surface, the shape of free surface is…….

a) plane

b) concave

c) convex

d) none of these

b) concave

Q.2) If the pressure outside free surface of liquid is less than that of pressure inside the free surface, the shape of free surface is…….

a) plane

b) concave

c) convex

d) none of these

c) convex

Q.3) If the pressure outside free surface of liquid is same as that of pressure inside the free surface, the shape of free surface is…….

a) plane

b) concave

c) convex

d) none of these

a) plane

Q.4) Which among the following are examples of capillary action…….

a) Filter paper can soak the water easily

b) Sap reaches to every topmost branch and leaf of tree.

c) ink in fountain pen

d) all of these

d) all of these

Q.5) If the pressure outside free surface of liquid is less than that of pressure inside the free surface, level of liquid inside capillary will be…….

a) will remain same

b) depressed by certain height

c) raised by certain height

d) either ‘a’ or b’

b) depressed by certain height

Q.6) If the pressure outside free surface of liquid is greater than that of pressure inside the free surface, level of liquid inside capillary will be…….

a) will remain same

b) depressed by certain height

c) raised by certain height

d) either ‘a’ or b’

c) raised by certain height

### ♦जिल्हा नुसार जाहिराती ♦

अहमदनगर अकोला अमरावती औरंगाबाद भंडारा बुलढाणा
चंद्रपुर धुले गढ़चिरौली गोंदिया हिंगोली जलगांव
जालना कोल्हापुर लातूर मुंबई नागपुर नांदेड़
नंदुरबार नाशिक उस्मानाबाद पालघर परभानी पुणे
रायगढ़ रत्नागिरि सांगली सातारा सिंधुदुर्ग सोलापुर
ठाणे वर्धा वाशिम यवतमाल बीड

### ♦शिक्षणानुसार जाहिराती ♦

७ वी (7th) दहावी (SSC) बारावी (HSC) डिप्लोमा आय.टी.आय पदवी
पदव्युत्तर शिक्षण बी.एड एम.एड एल.एल.बी / एल.एल.एम बीएससी एमबीए
बीसीए एमसीए बी.कॉम एम.कॉम GNM/ANM एमएससी
बी.फार्म एम.फार्म बी.ई एम.ई BAMS/BHMS एम.बी.बी.एस / एम.डी
बी.टेक एम.टेक MS-CIT