[店o-6]a=+竖jr'ar'a dt2 6-6+号眼-的) If Eo(t)=Acos@t Eml-2-r2）-422-r） Eo 4Eo dt2 Eerrortu -1 Eo 4 f=c=1 Veμ 2-60-2受心-爱Px1bx月 入 4 f=1 MHz in free space3x108 =300m 106 Ifb≤100m EQS approximation is valid. II.Conditions for Magnetoquasistatic Fields H (b)MQS system consisting of perfectly conducting loop driven by current source.The radius of the loop and diameter of its cross-section are (b) on the order of L. Courtesy of Hermann A.Haus and James R.Melcher.Used with permission. 6.641,Electromagnetic Fields,Forces,and Motion Lecture 3 Prof.Markus Zahn Page 3 of 126.641, Electromagnetic Fields, Forces, and Motion Lecture 3 Prof. Markus Zahn Page 3 of 12 ( ) () b 2 0 z z 2 r d E E b E r d r ' dr ' d 2 dt µ ⎡ ⎤ − =+ ⎣ ⎦ ε ∫ ( ) 2 2 2 0 2 d d E b r 4 dt µ = − ε ( ) ( ) 2 0 2 2 z 0 2 d E Er E r b 4 dt µ =+ − ε If E t A cos t 0 ( ) = ω ( ) ( ) 2 error 0 22 2 22 2 0 0 E d E 1 br br E 4E 4 dt µ = − =ω − ε εµ 2 2 error 0 E b 1 1 E 4 ω µ ⇒ ε   1 f c λ= = εµ 22 2 2 2 2c b c b 1b 2 4 ω π ωµ π λ λ= ⇒ω= ⇒ = ⇒ πλ π λ ε   f=1 MHz in free space 8 6 3 10 300m 10 × ⇒λ= = If b 100m  EQS approximation is valid. Courtesy of Hermann A. Haus and James R. Melcher. Used with permission. II. Conditions for Magnetoquasistatic Fields