1.

If the energy E=G^(p)h^(q)c^(r ) where G is the universal gravitational constant, h is the planck's constant and c is the velocity of light, then the values of p, q and r are respectively:a) -1/2,1/2 and 5/2 b) 1/2, -1/2 and -5/2 c) -1/2,1/2 and 3/2 d) 1/2, -1/2 and -3/2

Answer»

`-(1)/(2), (1)/(2) and (5)/(2)`
`(1)/(2), -(1)/(2) and -(5)/(2)`
`-(1)/(2), (1)/(2) and (3)/(2)`
`(1)/(2), -(1)/(2) and -(3)/(2)`

Solution :`E=G^(p)h^(Q)c^(r )`
Using dimensions we can write,
`[ML^(2)T^(-1)]=[M^(-1)L^(3)T^(-2)]^(p)[ML^(2)T^(-1)]^(q)[LT^(-1)]^(r )`
`therefore [M^(1)L^(2)T^(-2)]=[M^(-p)L^(3p)T^(-2p)][M^(q)L^(2Q)T^(-q)][L'T^(-r )]`
`=M^(-p+q)L^(3p_r)T^(-2p-q-r)`
Comparing the powers of M, L and T we GET
`therefore -p+q=1"...(2)"`
`3p+2q+r=2"...(3)"`
`-2p-q-r=-2`
`therefore 2p+q+r=2"...(4)"`
Solving (3) and (4) we get
`{:(" 3"p+2q+r=2),("2"p+q+r=2),("(-)(-)(-)(-)"),(bar(""p+q=0" ")"...(5)"),(""-p+q=1"...(2)"),(bar(""2q=1" ")):}`
`q=(1)/(2)`
From (5) `therefore p=-q=-(1)/(2)`
`therefore p=-(1)/(2)`
From (4) `therefore r=2-2p-q`
`=2-2(-(1)/(2))-(1)/(2)`
`=2+1-(1)/(2)=2(1)/(2)=(5)/(2)`
`r=(5)/(2)`
`therefore p=-(1)/(2), q=(1)/(2) and r=(5)/(2)`


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