( ( ( ( ( ( We ( saw ( that ( ( plane mirrors ) ( form ( virtual images ) ) ) ) ) ) , ) ( i.e. ( , ( ( the image ) ( is ( located ( behind ( the mirror ) ) ) ) ) ) ) ) and ) ( ( the ( light rays ) ) ( only ( appear ( to ( come ( from ( where ( ( the image ) ( is located ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (PRP We)) (VP (VBD saw) (SBAR (IN that) (S (NP (NN plane) (NNS mirrors)) (VP (VBP form) (NP (JJ virtual) (NNS images))))))) (, ,) (S (ADVP (RB i.e.)) (, ,) (NP (DT the) (NN image)) (VP (VBZ is) (VP (VBN located) (PP (IN behind) (NP (DT the) (NN mirror)))))) (CC and) (S (NP (DT the) (JJ light) (NNS rays)) (ADVP (RB only)) (VP (VBP appear) (S (VP (TO to) (VP (VB come) (PP (IN from) (SBAR (WHADVP (WRB where)) (S (NP (DT the) (NN image)) (VP (VBZ is) (VP (VBN located))))))))))) (. .)))
We saw that plane mirrors form virtual images, i.e., the image is located behind the mirror and the light rays only appear to come from where the image is located.
(ROOT (S (NP (NNP Plane) (NNS mirrors)) (VP (VBP work) (SBAR (IN because) (S (NP (DT the) (JJ light) (NNS rays)) (VP (VBP create) (NP (NP (DT a) (JJ virtual) (NN image)) (PP (IN behind) (NP (DT the) (NN mirror)))))))) (. .)))