Can anyone tel me how to determine the specific resistance of a wire using Post Office Box method?

It wud be more helpful if some illustrations r also given..

Can neone explain me the principle on which carbon dating calculation is done?

 

i mean the physical process which leads to such a calculation..

condition for concurrency, delta =0

 

| a  1  1 |

| 1  b  1 | = 0

| 1  1  c |

applying

(C₂ - C₁) and (C₃ - C₁)

 

delta = a(1-a)(c-1) - (1-a)(c-1) - (1-a)(b-1) =0

dividing by (1-a)(1-b)(1-c), we get

 

a/(1-a)  +  1/(1-b)  +  1/(1-c) =0 , v get

 

1/(1-b) + 1/(1-c) = 1a/(1-a)

add  1/(1-a) to both sides,

 

1/(1-a) + 1/(1-b) + 1/(1-c) = (1-a)/(1-a) = 1 

| 1  2  1 |

| 3  4  1 | = 1

| x  y  1 |

 

on evaluation gives, 2x - 2y + 3 = 0

and the given condition gives x^2 + y^2 - 4x -6y +11 =0

 

substituting the first condition and simplyfying we get

 

5y^2 - 18y +4 =0

the discriminant of this expression is +ve..hence it has 2 real roots..n fer each root v hav one value of x..

 

hence maximum no. of such points C is "2"..

The equation of the line(s) thru the point (2,3)

and making an intercept of length 2 units between the lines

y+2x=3

and

y+2x=5 are...