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A toroid has a mean radius R equal to 20//pi cm, and a total of 400 turns of wire carrying a current of 2.0 A. An aluminium ring at temperature 280 K inside the toroid provides the core. If the magnetisation I is 4.8 xx 10^(-2) A m^(-1), then, choose the correct option(s). |
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Answer» MAGNETIC intensity in the core is `1000 A m^(-1)` `n = (400)/(2piR)` The magnetic intensity H in the core is `H = ni = (400xx 2.0A)/(2pi20/rxx10^(-2)m)=2000Am^(-1)` The susceptibility is `X = I/H = (4.8xx10^(-2)Am^(-1))/(2000Am^(-1))=2.4xx10^(-5)` The susceptibility X of a paramagncrie substance VARIES with absolute temperature as X = c/T, `therefore X_(2)//X_(1) = T_(1)//T_(2)` The susceptibility of aluminium at temperature 320 K is. therefore, `X_(2) = (280)/(320) xx 2.4 xx 10^(-5) = 2.1 xx 10^(-5)` Thus the magnetisation at 320 K is `I = XH -= 2.1 xx 10^(-5) xx 2000 Am^(-1) = 4.2 xx 10^(-2) Am^(-1)` |
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