Thursday, January 8, 2009

MultipleChoiceQuestions,Units-Dimensions

41)Which of the following is dimensionally correct formula.

a)V=ut + at b) v+u = at c) V/u =at d) vt = u -a

Soln: The dimensions of L and T are same in all the terms of V+u=at.Hence, according to priciple of homogeneity it a dimensionally correct equation.

42) The dimensional formula of coefficient of kinematic viscosity is

a) M^0L^2T^{-1} b) M^1L^2T^{-1} c) M^1L^2T^{-3} d) M^0L^3T^{-1}

43) Which of the following is not the unit of energy?

a) joule b) Nm c) W d) kg m^2sec^{-2}

44) Dimensional formula of latent heat is

a) M^1L^1T^{-2} b) 1^0L^2T^{-2} c) M^1L^2T^{-1} d)M^0L^2T^{-2}

45) Pair of quantities having same dimensional formula are

a) velocity , Impulse b)Force,Weight C)Impulse ,Inertia d) Angular momtntum, Linear momentum

46) If R is resistance and L is the inductance,then the dimensions of \frac{R}{L} will be same as the dimensions of . . . .

a)time b) speed c) frequency d) acceleration

Soln: Dimensional formula of resistance R =M^1L^2T^{-3}I^{-2} and dimensional formula of Inductance is L=M^1L^2T^{-2}I^{-2} .

\frac{R}{L} =\frac{M^1L^2T^{-3}I^{-2}} {M^1L^2T^{-2}I^{-2}} = T^{-1} which is the dimensional formula of frequency.

47) If the unit of power is 100 erg/minute,the unit of force is 100 dyne and the unit of time is 100 seconds, the unit of length is

a) 5/3 cm b) 2/3 cm c) 1/3 cm d) none

Soln: P = M^1L^2T^{-3} = 100 erg/min =(100/60) erg/sec

F=M^1L^1T^{-2} = 100dyne T=M^0L^0T^1 = 100 sec

P=(M^1L^1T^{-2})(L)(T^{-1}) = F(L)(T^{-1})

L = PF^{-1}T = (100/60)(1/100)(100) =5/3

48 ) If M^aL^bT^c is the dimensional formula of Electric power, find the value of 5a+2b-6c.

a) 25 b) 27 c) 30 d)-9

Soln: Dimensional formula of Electric power = M^1L^2T^{-3} =M^aL^bT^c

Comparing the powers of M,L and T we get a=1,b=2 and c=-3 .

Therefore 5a+2b-6c = 5(1)+2(2)-6(-3) =5+4+18 =27.

49) If M^aL^bT^cI^d is the dimensional formula of Magnetic moment, fine the value of a-2b+3c -d

a) 5 b) 7 c)3 d)-5

Soln: Dimensional formula of Magnetic moment is M^0L^2T^0I^1 =M^aL^bT^cI^d

Comparing the powers of M,L,T and I we get a=0,b=2, c=0 and d=1 ;

Therefore a-2b+3c-d = 0-2(2)+3(0)-1 = -4-1 = -5.

50) If M^{5a}L^bT^{3c}I^{2d} is the dimensional formula of magnetic pole strength, fine the value 5a+b+3c+2d

a) 3 b) 2 c) -2 d)0

Dimensional formula of Magnetic pole strength is M^0L^1T^0I^1 = M^{5a}L^bT^{3c}I^{2d}

Comparing the powers of M,L,T and I we get 5a=0,b=1,3c=0 and 2d=1 ;

Therefore 5a+b+3c+2d = 0+1+0+1 = 2.

Posted by chavan gyanraj at 5:22 AM
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2 comments:

  1. AnonymousJune 8, 2009 at 6:19 AM

    add some more standerd f#$k!ng questons

    ReplyDelete
  2. AnonymousMarch 28, 2011 at 5:31 AM

    i think it helps me a lot

    ReplyDelete

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