An inductor -coil of inductance 17 mH is constructed from a cpper wire of length 100 m and cross sectional area 1 mm. caluclate the time constant of the circuit if this inductor is joined across an ideal battery The resistivity of copper =1.7×10−8Ωm.
L=17mH,l=100m,A=1mm2=1×10−6m2∴fcv=1.7×10−8Ω−mR=fcvLA=1.7×10−2×1001×10−6=1.7Ωi=LR=17×10−31.7=10−2Sec=10sec.