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To measure large distances, we employ an important method called the parallax method.
If we look at an object with one eye closed, its position seems to be moved a little from the original position.
If you look at a pencil held in front of your eyes against a fixed reference point on a plain wall, with your left eye, closing your right eye and then with your right eye, closing your eye you observe that the position of the pencil seems to change with respect to the fixed reference point on the wall. This is called parallax.
You may call the two eyes are two different viewpoints, since when used separately; they create different lines of sights.
Distance between these two viewpoints or points of observation is called basis. Here, the basis is equal to the distance between two eyes.
We use exactly the same method to measure the distance of a distant star. Instead of two eyes, we view the star from two different observatories on the earth at the same time.
To measure very small distances such as the size of a molecule, special microscopes need to be used. We cannot employ devices like a Vernier callipers or a screw gauge to measure such lengths.
All instruments such as simple microscope, optical microscope or an electron microscope have a certain limitations in measuring lengths. However, we can use a simpler method to estimate the size of a molecule.
Let us take some oleic acid. Oleic acid is a soapy liquid with large molecular size of the order of 10^–9 metre.
We need to form a monomolecular layer of oleic acid on water surface so as to measure the thickness or diameter of a molecule of the acid.
We learnt how to measure a tiny molecular distance or a massive stellar distance.

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Type of force in chepter physical world

Posted by Suraj Prajapat 6 years, 7 months ago

CBSE > Class 11 > Physics

1 answers

Komal Sharma 6 years, 7 months ago

Their are 4 types of force :gravitational force , electromagnetic force , strong force , weak force

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Cold air is heavy it goes down but why at the top of mountains there is a cold climate?

Posted by Suyash Mishra 6 years, 7 months ago

CBSE > Class 11 > Physics

4 answers

Aditya Saha? 6 years, 7 months ago

Hello Anjali

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Yash Goswami????? 6 years, 7 months ago

Because of high pressure and due to the condensed water present in the clouds r near to the top of mountain

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Rana Basak 6 years, 7 months ago

Because of high pressure

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Dhruv Choudhary 6 years, 7 months ago

Hlo

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Chapter 1 NCERT solutions

Posted by Nitin Kumar 6 years, 7 months ago

CBSE > Class 11 > Physics

1 answers

Yash Goswami????? 6 years, 7 months ago

See in my cbse guide if got problem then ask

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Give an example of physical quantity that has no dimensions but has units

Posted by Ansel Jawahar 007 6 years, 7 months ago

CBSE > Class 11 > Physics

5 answers

Sinchana Malagond 6 years, 7 months ago

Angle

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Priya Singh 6 years, 7 months ago

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Priya Singh 6 years, 7 months ago

Angle has no dimension but has unit

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H!Mαη$Hμ Ұαδαυ ✔️ 6 years, 7 months ago

This is not possible

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Yash Goswami????? 6 years, 7 months ago

I don't know that there is such type of physical quantity exist in the world

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Hyyy??

Posted by Ship.. ??? 6 years, 7 months ago

CBSE > Class 11 > Physics

5 answers

Yash Goswami????? 6 years, 7 months ago

Hlo kbi

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Yash Goswami????? 6 years, 7 months ago

Hlo

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Dhruv Choudhary 6 years, 7 months ago

Anyone frndship with me

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Dhruv Choudhary 6 years, 7 months ago

How r u

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Dhruv Choudhary 6 years, 7 months ago

Hii

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First of all as we know earth is moving around the sun on its own orbit. But my question is, how it is moving? And is there any real orbit on which earth like other planets are moving. And in that same route how it is happening. Just think about this...

Posted by Bhai Ki Bhai 6 years, 7 months ago

CBSE > Class 11 > Physics

1 answers

Yash Goswami????? 6 years, 7 months ago

There is gravitational force acting on earth in equal magnitude due to which earth revolve around the sun but of its own gravitational force it revolvs in it orbit

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Process of measurment of physical quantities

Posted by Veena Rani 6 years, 7 months ago

CBSE > Class 11 > Physics

1 answers

Veena Rani 6 years, 7 months ago

1.The selection of unit. 2.To find out the no. Of times that unit is cintained in the physical quatity.

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Suppose length depends upon gravitational constant (G) velocityof light(C) & frequency (F) .show dimensional formula for L

Posted by Prabhat Bolia 6 years, 7 months ago

CBSE > Class 11 > Physics

0 answers

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What is fundamental units?

Posted by Ankit Rao 6 years, 7 months ago

CBSE > Class 11 > Physics

3 answers

Himanshu Singh 6 years, 7 months ago

Those units which cannot be breakdown

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Prashi Jain 6 years, 7 months ago

its just the units which we have assumed and so there is no logic

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Yogita Ingle 6 years, 7 months ago

Each base quantity is defined in terms of a certain basic arbitrarily chosen but properly standardised reference standard called unit (such as metre, kilogram,second,ampere,kelvin,mole,and candela.The units for the fundamental base quantities are called fundamental or base units and two supplementary units in relation to quantities plane angle and solid angle radian, Ste radian..

S.No.	Fundamental Quantities	Fundamental Units	Symbol
1.	Length	metre	m
2.	Mass	kilogram	kg
3.	Time	second	S
4.	Temperature	kelvin	kg
5	Electric current	ampere	A
6	Luminous intensity	candela	cd
7	Amount of substance	mole	mol