A gas of sodium atoms emits collimated yellow light(=589nm) a) What is the energy (eV) of one photon? b)What is the frequency of the light? The light enters glass (n=1.5) at an angle of incidence of 30degrees. c)What are the angles of reflection and transmission? d)What is the speed of the light inside the glass? e)What is the wavelength of the light inside the glass? A gas of sodium atoms emits collimated yellow light(=589nm) a) What is the energy (eV) of one photon? b)What is the frequency of the light? The light enters glass (n=1.5) at an angle of incidence of 30degrees. c)What are the angles of reflection and transmission? d)What is the speed of the light inside the glass? e)What is the wavelength of the light inside the glass?
Explanation / Answer
wavelength = 589 nm = 589 * 10 ^ -9 m (a). Energy of one photon E = hc / where h = planck's constant = 6.625 * 10 ^-34Js c= speed of light = 3 * 10 ^ 8 m / s plug the values E = 3.374 * 10 ^ -19 J = ( 3.374 * 10 ^ -19 ) / ( 1.6 * 10 ^ -19 ) eV = 2.108 eV (b). frequency f = c / = ( 3 *10 ^ 8 ) / ( 589* 10 ^ -9 ) = 5.093 * 10 ^14 Hz (c). speed of light in glass v = c / n = ( 3 * 10 ^ 8 ) / 1.5 = 2 * 10 ^ 8 m / s (e). wavelength of the light inside the glass ' = / n = 589 nm / 1.5 = 392.66 nm