Physics And Measurement Question 32

Question: The speed of light (c) , gravitational constant (G) and Planck’s constant (h) are taken as the fundamental units in a system. The dimension of time in this new system should be

[AMU 1995]

Options:

A) G1/2h1/2c5/2

B) G1/2h1/2c1/2

C) G1/2h1/2c3/2

D) G1/2h1/2c1/2

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Answer:

Correct Answer: A

Solution:

Time cxGyhzT=kcxGyhz

Putting the dimensions in the above relation

[M0L0T1]=[LT1]x[M1L3T2]y[ML2T1]z

[M0L0T1]=[My+zLx+3y+2zTx2yz] Comparing the powers of M,L and T

y+z=0 -(i)

x+3y+2z=0 -(ii)

x2yz=1 -(iii)

On solving equations (i) and (ii) and (iii) x=52,y=z=12

Hence dimension of time are [G1/2h1/2c5/2]



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