Nā nīnau hoʻohālike e kūkākūkā ana i nā nalu electromagnetic
ʻO nā nalu electromagnetic he mau nalu i hoʻokumu ʻia e nā kahua uila a me nā kahua magnetic e hoʻopuehu ana ma o kahi hakahaka ma ka wikiwiki o ka mālamalama. He mea nui kēia mau nalu i nā ʻano like ʻole o ke ola, mai ke kamaʻilio ʻana a i ke olakino. I mea e hoʻomaopopo maikaʻi ai i kēia manaʻo, e kūkākūkā mākou i kekahi mau pilikia hoʻohālike e pili ana i nā nalu electromagnetic a me kā lākou wehewehe ʻana.
Nīnau 1: Ke helu ʻana i ka lōʻihi o ka nalu
He 500 MHz ka alapine (frequency) o kahi nalu electromagnetic. E hoʻoholo i kona nalu!
Kūkākūkā:
Alapine (f) = 500 MHz = 500 x 10^6 Hz
Ka wikiwiki o ke kukui (c) = 3 x 10^8 m/s
Hiki ke helu ʻia ka lōʻihi o ka nalu (λ) me ka hoʻohana ʻana i ke ʻano hana:
\[ \lambda = \frac{c}{f} \]
Eia nā kikoʻī o ka helu ʻana:
\[ \lambda = \frac{3 \times 10^8 \, \text{m/s}}{500 \times 10^6 \, \text{Hz}} \]
\[ \lambda = \frac{3 \times 10^8}{5 \times 10^8} \]
\[ \lambda = 0.6 \, \text{mika} \]
No laila, ʻo ka lōʻihi o ka nalu electromagnetic he 0.6 mika.
Nīnau 2: Ikehu o kahi Photon
He aha ka ikehu o kahi photon nona ke alapine (frequency) o 6 x 10^14 Hz?
Kūkākūkā:
Hiki ke helu ʻia ka ikehu (E) o kahi photon me ka hoʻohana ʻana i ke ʻano hana a Planck:
\[ E = hf \]
Ma hea:
– ʻo h ke kūpaʻa o Planck = 6.626 x 10^-34 J·s
– ʻo f ke alapine (frequency) = 6 x 10^14 Hz
No laila,
\[ E = (6.626 \times 10^{-34} \, \text{J·s}) \times (6 \times 10^{14} \, \text{Hz}) \]
\[ E = 3.9756 \times 10^{-19} \, \text{J} \]
No laila, ʻo ka ikehu o ka photon he 3.9756 x 10^-19 joules.
Nīnau 3: Ka wikiwiki o nā nalu electromagnetic i loko o kahi Medium
Inā ʻo ka wikiwiki o ka mālamalama i loko o ka hakahaka he 3 x 10^8 m/s a ʻo ka helu kuhikuhi refractive o kahi medium he 1.5, he aha ka wikiwiki o ka mālamalama i loko o kēlā medium?
Kūkākūkā:
Hiki ke helu ʻia ka wikiwiki o ka mālamalama i loko o kahi waena (v) me ka hoʻohana ʻana i ka helu kuhikuhi refractive (n):
\[ n = \frac{c}{v} \]
Ma hea:
– ʻo c ka wikiwiki o ka mālamalama i loko o kahi hakahaka = 3 x 10^8 m/s
– ʻo n ka helu kuhikuhi refractive = 1.5
Ke helu nei iā v:
\[ v = \frac{c}{n} \]
\[ v = \frac{3 \times 10^8 \, \text{m/s}}{1.5} \]
\[ v = 2 \times 10^8 \, \text{m/s} \]
No laila, ʻo ka wikiwiki o ka mālamalama ma kēia waena he 2 x 10^8 mika i kekona.
Nīnau 4: Nā Nalu Electromagnetic ma nā Alapine Lekiō
Hoʻolaha ke kahua lekiō X ma ke alapine (frequency) o 100 MHz. He aha ka nalu o ka hōʻailona?
Kūkākūkā:
Alapine (f) = 100 MHz = 100 x 10^6 Hz
Ka wikiwiki o ke kukui (c) = 3 x 10^8 m/s
Hiki ke helu ʻia ka lōʻihi o ka nalu (λ) me ka hoʻohana ʻana i ke ʻano hana:
\[ \lambda = \frac{c}{f} \]
No laila,
\[ \lambda = \frac{3 \times 10^8 \, \text{m/s}}{100 \times 10^6 \, \text{Hz}} \]
\[ \lambda = \frac{3 \times 10^8}{1 \times 10^8} \]
\[ \lambda = 3 \, \text{mika} \]
No laila, ʻo 3 mika ka lōʻihi o ka nalu o ka hōʻailona lekiō.
Nīnau 5: Mana i loaʻa e kahi Antenna
Loaʻa i kahi antenna kahi hōʻailona nalu electromagnetic me ka mana o 0.1 W ma ke alapine (frequency) o 2.4 GHz. Ehia mau photons i kekona e loaʻa i ka antenna?
Kūkākūkā:
Mana (P) = 0.1 W = 0.1 J/s
Alapine (f) = 2.4 GHz = 2.4 x 10^9 Hz
Hiki ke helu ʻia ka ikehu o hoʻokahi photon (E) me ka hoʻohana ʻana i ke ʻano hana:
\[ E = hf \]
\[ E = (6.626 \times 10^{-34} \, \text{J·s}) \times (2.4 \times 10^9 \, \text{Hz}) \]
\[ E = 1.59024 \times 10^{-24} \, \text{J} \]
Hiki ke helu ʻia ka helu o nā photons i kekona (N) ma ka puʻunaue ʻana i ka mana e ka ikehu no kēlā me kēia photon:
\[ N = \frac{P}{E} \]
\[ N = \frac{0.1 \, \text{J/s}}{1.59024 \times 10^{-24} \, \text{J}} \]
\[ N = 6.29 \times 10^{22} \, \text{photons/s} \]
No laila, loaʻa i ka antenna ma kahi o 6.29 x 10^22 photons i kekona.
Ka hopena
He ʻokoʻa loa ke kūkākūkā ʻana o nā nalu electromagnetic a uhi i nā ʻano he nui, mai ka helu ʻana i ka nalu lōʻihi, ka ikehu photon, a i ka wikiwiki o ka nalu i loko o kahi medium. Manaʻo ʻia nā pilikia hoʻohālike a me kā lākou wehewehe ʻana ma luna e kōkua iā ʻoe e hoʻomaopopo i ke kumumanaʻo o nā nalu electromagnetic i ka hohonu a me ka hoʻohana ʻana. Manaʻolana, he mea pono kēia ʻatikala a hoʻonui i ka ʻike o ka poʻe heluhelu i nā nalu electromagnetic.
