A plate of area `10 cm^2` is to be electroplated with copper `(density 9000 kg m^(-3)` to a thickness of 10 micrometres on both sides, using a cell of `12 V`. Calculate the energy spend by the cell in the process of deposition. If this energy is used to heat `100 g` of water, calculate the rise in the temperature of the water. ECE of copper `= 3 xx 10^(-7) kg C^(-1)` and specific heat capacity of water `= 4200 J kg^(-1) K^(-1)`.

Answer

A, B

Explanation

`A = 10 cm^2 = 10xx10^(-4) m^2, `
`delta = 9000 Kg//m^3`
` t = 10mu m = 10^(-5) m`
` Volume = A(2t) `
`= 10xx10^(-4) xx 2xx10xx10^(-6)`
` 2xx10^2 xx 10^(-10)`
`= 2xx10^(-8) m^3`
`mass = 2xx10^(-8) xx9000`
`= 18xx10^(-5) Kg`
`W = zxxq`
`=18xx10^(-5) = 3xx10^(-7) xxq`
`rArr q = 6 xx 10^2`
` V = (W)/(q)`
` W = Vq `
`= 12xx 6 xx 10^2`
= 72xx10^2 = 7.2KJ`
That workes rise in temperature for 100 gm water So,
`7.2xx10^3 = 100xx10^(-3)xx4200xxDelta theta`
` rArr Delta theta = 17K`