Ngā taputapu whatu, ngā karaihe whakapā – ngā raruraru me ngā otinga

1. Ko te mana o te karāhe whakapā he -5 Diopt.

(a) He karāhe whakapūmau , he karāhe wehewehe rānei te karāhe whakapā?

(b) He aha te roa o te arotahi o te karāhe whakapā?

Mōhiotia:

Mana o te karu (P) = -5 D

Rongoā:

(a) He karāhe arotahi, he karāhe arotahi rānei?

Ko te tohu tango o te kaha o te arotahi e tohu ana ko te arotahi whakapā te arotahi wehewehe.

(b) Te roa o te arotahi?

P = 1/f

-5 = 1/w

f = 1/-5 = -0.2 m = -20 cm

Ko te roa arotahi o te karāhe arotahi wehewehe he 20 henemita.

(c) Kanohi tiro tata, kanohi tiro tawhiti rānei?

-1/ d _i= 1/ f – 1/ d _o

-1/ d _i= -1/20 – 1/~ = -1/20 – 0

-1/ d _i= -1/20

d _i= 20 cm

Ko te tawhiti o te ahua he 20 henimita. Ko te 20 henimita te pūwāhi tawhiti o te kanohi tiro tawhiti. Mō te kanohi noa, ko te pūwāhi tawhiti ko te mutunga kore.

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2. Ko te kaha o te karāhe whakapā he 1.5 Diopters.

(a) He karāhe whakapūmau, he karāhe wehewehe rānei te karāhe whakapā?

(b) He aha te roa o te arotahi o te karāhe whakapā?

Mōhiotia:

Mana arotahi (P) = 1.5 Diopters

Rongoā:

(a) te arotahi whakapūmau, te arotahi wehewehe rānei

Ko te tohu tāpiri o te kaha o te arotahi e tohu ana he arotahi hūnuku te arotahi whakapā.

(b) Te roa o te arotahi

P = 1/f

1.5 = 1/w

f = 1/ 1.5 = 0.67 mita = 67 henimita

Ko te roa arotahi o te karāhe arotahi ko 67 henemita.

(c) Kanohi tiro tata, kanohi tiro tawhiti rānei

-1/ d _i= 1/ f – 1/ d _o

-1/ d _i= 1/67 – 1/25 = 25/1675 – 67/1675 = -42/1675

– d _i= -1675/42 = -40 henimita = -0.40 mita

d _i= 40 cm

Ko te tawhiti o te ahua he 40 henimita. Ko te 20 henimita te tawhiti e tata ana ki te pito o te kanohi tiro tawhiti. Mō te kanohi noa, ko te pito tata he 25 henimita.

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