Home
Class 12
PHYSICS
If u1 and u2 are the units selected in t...

If `u_1` and `u_2` are the units selected in two systems of measurement and `n_1` and `n_2` their numerical values, then

A

`n_1u_1=n_2u_2`

B

`n_1u_1+n_2u_2=0`

C

`n_1n_2=u_1u_2`

D

`(n_1+u_1)l=(n_2+u_2)`

Text Solution

Verified by Experts

The correct Answer is:
A
Pysical quantity `(p)=` numerical value `(n)xxunit(u)` If pysical quantity remains constant then `nprop(1)/(u)` `because` `n_1u_1=n_2u_2`.
Doubtnut Promotions Banner Mobile Dark
|

Topper's Solved these Questions

  • CENGAGE PHYSICS DPP

    CENGAGE PHYSICS ENGLISH|Exercise subjective type|51 Videos

  • CENGAGE PHYSICS DPP

    CENGAGE PHYSICS ENGLISH|Exercise Multiple correct Answer Type|54 Videos

  • CAPACITOR AND CAPACITANCE

    CENGAGE PHYSICS ENGLISH|Exercise Integer|5 Videos

  • COULOMB LAW AND ELECTRIC FIELD

    CENGAGE PHYSICS ENGLISH|Exercise Single Answer Correct Type|22 Videos

Similar Questions

Explore conceptually related problems

A physical quantity is measured and the result is expressed as nu where u is the unit used and n is the numberical value. If the result is expressed in various units then

1 joule of energy is to be converted into new system of units in which length is measured in 10 metre, mass in 10 kg and time in 1 minute. The numerical value of 1 J in the new system is :-

Force acting on a particle is 5 N. If units of length and time are double and unit of mass is halved then find the numerical value of force in the new system of unit .

STATEMENT 1 When the unit for measurement of a quantity is changed, its numerical value changes STATEMENT 2 Smaller the unit of measurement matter is its numerical value

If u_(1), u_(2) and v_(1), v_(2) are the initial and final velocities of two particles before and after collision respectively, then (v_(2)-v_(1))/(u_(1)-u_(2)) is called ___________.

The numerical values and units of a physical quantity in two different system of units are n_(1), n_(2) and u_(1), u_(2) respectively. Then

Two path 1 and 2 are shown in figure. If the change in internal energies are U, and U2 for path 1 and 2 respectively, then

If (x , y) and (x ,y) are the coordinates of the same point referred to two sets of rectangular axes with the same origin and it u x+v y , where u and v are independent of xa n dy , becomes V X+U Y , show that u^2+v^2=U^2+V^2dot

Collision cross-section is an area of an imaginary sphere of radius sigma around the molecule within which the centre of another molecule cannot penetrate. The volume swept by a single molecule in unit time is V=(pisigma^(2))overline(u) where overline(u) is the average speed If N^(**) is the number of molecules per unit volume, then the number of molecules within the volume V is N=VN^(**)=(pisigma^(2)overline(u))N^(**) Hence, the number of collision made by a single molecule in unit time will be Z=N=(pi sigma^(2)overline(u))N^(**) In order to account for the movements of all molecules, we must consider the average velocity along the line of centres of two coliding molecules instead of the average velocity of a single molecule . If it is assumed that, on an average, molecules collide while approaching each other perpendicularly, then the average velocity along their centres is sqrt(2)overline(u) as shown below. Number of collision made by a single molecule with other molecule per unit time is given by Z_(1)=pisigma^(2)(overline(u)_("rel"))N^(**)=sqrt(2) pisigma^(2)overline(u)N^(**) The total number of bimolecular collisions Z_(11) per unit volume per unit time is given by Z_(11)=(1)/(2)(Z_(1)N^(**))"or" Z_(11)=(1)/(2)(sqrt(2)pisigma^(2)overline(u)N^(**))N^(**)=(1)/(sqrt(2))pisigma^(2)overline(u)N^(**2) If the collsion involve two unlike molecules then the number of collisions Z_(12) per unit volume per unit time is given as Z_(12)= pisigma _(12)^(2)(sqrt((8kT)/(pimu)))N_(1)N_(2) where N_(1) and N_(2) are the number of molecules per unit volume of the two types of molecules, sigma_(12) is the average diameter of the two molecules and mu is the reduced mass. The mean free path is the average distance travelled by a molecule between two successive collisions. We can express it as follows : lambda=("Average distance travelled per unit time")/("NO. of collisions made by a single molecule per unit time")=(overline(u))/(Z_(1)) "or "lambda=(overline(u))/(sqrt(2)pisigma^(2)overline(u)N^(**))implies(1)/(sqrt(2)pisigma^(2)overline(u)N^(**)) For a given gas the mean free path at a particular pressure is :

Collision cross-section is an area of an imaginary sphere of radius sigma around the molecule within which the centre of another molecule cannot penetrate. The volume swept by a single molecule in unit time is V=(pisigma^(2))overline(u) where overline(u) is the average speed If N^(**) is the number of molecules per unit volume, then the number of molecules within the volume V is N=VN^(**)=(pisigma^(2)overline(u))N^(**) Hence, the number of collision made by a single molecule in unit time will be Z=N=(pi sigma^(2)overline(u))N^(**) In order to account for the movements of all molecules, we must consider the average velocity along the line of centres of two coliding molecules instead of the average velocity of a single molecule . If it is assumed that, on an average, molecules collide while approaching each other perpendicularly, then the average velocity along their centres is sqrt(2)overline(u) as shown below. Number of collision made by a single molecule with other molecule per unit time is given by Z_(1)=pisigma^(2)(overline(u)_("rel"))N^(**)=sqrt(2) pisigma^(2)overline(u)N^(**) The total number of bimolecular collisions Z_(11) per unit volume per unit time is given by Z_(11)=(1)/(2)(Z_(1)N^(**))"or" Z_(11)=(1)/(2)(sqrt(2)pisigma^(2)overline(u)N^(**))N^(**)=(1)/(sqrt(2))pisigma^(2)overline(u)N^(**2) If the collsion involve two unlike molecules then the number of collisions Z_(12) per unit volume per unit time is given as Z_(12)= pisigma _(12)^(2)(sqrt((8kT)/(pimu)))N_(1)N_(2) where N_(1) and N_(2) are the number of molecules per unit volume of the two types of molecules, sigma_(12) is the average diameter of the two molecules and mu is the reduced mass. The mean free path is the average distance travelled by a molecule between two successive collisions. We can express it as follows : lambda=("Average distance travelled per unit time")/("NO. of collisions made by a single molecule per unit time")=(overline(u))/(Z_(1)) "or "lambda=(overline(u))/(sqrt(2)pisigma^(2)overline(u)N^(**))implies(1)/(sqrt(2)pisigma^(2)overline(u)N^(**)) Three ideal gas samples in separate equal volume containers are taken and following data is given : {:(" ","Pressure","Temperature","Mean free paths","Mol.wt."),("Gas A",1atm,1600K,0.16nm,20),("Gas B",2atm,200K,0.16nm,40),("Gas C",4atm,400K,0.04nm,80):} Calculate ratio of collision frequencies (Z_(11)) (A:B:C) of following for the three gases.

Home
Profile