(use unitconv)

(define-unit-prefix    milli second ms)
(define-unit-prefix    milli volt   mV)
(define-unit-prefix    milli amp    mA)
(define-unit-prefix    nano amp     nA)
(define-unit-prefix    micro siemens uS)

(define-quantity   CurrentDensity        (/ Current Area))

(define-unit amp-per-square-meter CurrentDensity (/ A (* m m)) A/m2)

(define-unit milliamp-per-square-centimeter CurrentDensity (/ mA (* cm cm)) mA/cm2)

(print milliamp-per-square-centimeter)
(print amp-per-square-meter)

(print (unit-convert amp-per-square-meter milliamp-per-square-centimeter))