generally the electrical resistance of metals rises with temp, and you know or have been given a figure for resistance at one temp say R1 resistance at T1.
But you want to know how the circuit will behave at another temp T2.
If you know the coefficient that relates a change in temp to a change in resistance, normally as so many percent or a certain fraction per degree, you can deduce the resistance at the new temp.
R2 = R1(1 + C* (T2-T1)) sort of thing, if C is expressed as reciprocal degrees - it is about 4E-3 (ie..004) per degree celcius. at room temp for aluminium, so 2 might be for a 50 degree rise if you have a 20 degree figure and want it at 70c or the reverse.
re-arrange to use the letters and figures you have, not sure what a and b are in this book.
generally the electrical resistance of metals rises with temp, and you know or have been given a figure for resistance at one temp say R1 resistance at T1.
But you want to know how the circuit will behave at another temp T2.
If you know the coefficient that relates a change in temp to a change in resistance, normally as so many percent or a certain fraction per degree, you can deduce the resistance at the new temp.
R2 = R1(1 + C* (T2-T1)) sort of thing, if C is expressed as reciprocal degrees - it is about 4E-3 (ie..004) per degree celcius. at room temp for aluminium, so 2 might be for a 50 degree rise if you have a 20 degree figure and want it at 70c or the reverse.
re-arrange to use the letters and figures you have, not sure what a and b are in this book.
