1.

Two wires of same material having lengths and radii in the ratio of 3 : 4 and 3 : 2 respectively are connected in parallel with a potential source of 6V. the ratio of currents flowing through them I_(1) : I_(2)= ..... .

Answer»

`1: 3 `
`1: 2`
`3: 1 `
`2 : 1 `

Solution :` 3: 1`
`R = (rho l)/(A) = (rho l)/(PI r^(2))`
`therefore R prop (l)/(r^(2))`
` therefore (R_(1))/(R_(2)) = (l_(1))/(l_(2)) XX ((r_(2))/(r_(1)))^(2) `
`therefore (R_(2))/(R_(1)) = (l_(2))/(l_(1)) xx ((r_(1))/(r_(2)))^(2)"" `... (1)
But V`I_(1) R_(1) = I_(2) R_(2) `
`therefore (I_(1))/(I_(2)) = (R_(2))/(R_(1))`....(2)
From equation (1) and (2).
`(I_(1))/(I_(2)) = (4)/(3) xx ((3)/(2))^(2) = (4)/(3) xx (9)/(4) = (3)/(1)`


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