NEET Physics Units and Measurement Questions Solved


(1)

Where K is thermal conductivity

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mcxGy.hzML°T°=LT-1x.M-1L3T-2y.ML2T-1zML°T°=M-y+z.Lx+3y+2z.T-x-2y-zOn comparing dimensions on both sides:       -y+z=1                  ........i       x+3y+2z=0           ........ii       -x-2y-z=0          ........iiiii+iii-    y+z=0                     y=-zput it in euqation i                     +z+z=1                     z=+12                     y=-12                     x=12Hence m c12G-12h12

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Surface tension S =ForceLength=MLT-2L=MT-2Let  Surface tension S =k ExVyTzPutting dimensions on both sides,[MT-2] = [ML2T-2]x[LT-1]y[T]zComparing powers  of M, L and T on both sides1 =x                                   ....... Power of M0 =2x + y                                    ..... Power of L            y= -2x = -2   -2 = -2x -y +z                   ........... ..... Power of Zz= 2x +y -2    =2 -2 -2 = -2Putting values of x, y and z in above formulaS =k E1V-2T-2

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        [Only for Dropper batch]  

V =LitTherefore , L =Vti

Also, V=iRTherefore R =Vi

so, LR= VtiVi=t

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    [Only for dropper batch]

(3)

Electrostatic pressure = 12oE2Dimension of Pressure = ML-1T-2Electromagnetic energy per unit volume = B22μoDimension = EnergyVolume=ML2T-2L3 =ML-1T-2    same as pressure

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PMT - 1989

Light year is a unit of    

(1) Time

(2) Mass

(3) Distance

(4) Energy

(3) Light year is a distance which light travels in one year.

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The magnitude of any physical quantity

(1) Depends on the method of measurement

(2) Does not depend on the method of measurement

(3) Is more in SI system than in CGS system

(4) Directly proportional to the fundamental units of mass, length and time

(2) Because magnitude is absolute.

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PMT - 1990

Which of the following is not equal to watt 

(1) Joule/second

(2) Ampere × volt

(3) (Ampere)2 × ohm

(4) Ampere/volt

(4)

Power=EnergyTime = Joule/second  = WattAlso for resistance R, Power = Voltage X Current =Ampere × volt =WattAlso, Voltage = Current X Resistance Power = Current2 X Resistance = Ampere2 × Ohm = Watt

 

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