huygens' principle of superposition

space

U+0020

apostrophe

U+0027

latin small letter c

U+0063

latin small letter e

U+0065

latin small letter f

U+0066

latin small letter g

U+0067

latin small letter h

U+0068

latin small letter i

U+0069

latin small letter l

U+006C

latin small letter n

U+006E

latin small letter o

U+006F

latin small letter p

U+0070

latin small letter r

U+0072

latin small letter s

U+0073

latin small letter t

U+0074

latin small letter u

U+0075

latin small letter y

U+0079