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Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: 000_katie_000 on April 05, 2005, 10:38:29 AM

Title: Questions (quantum, frequency, wavelength...)
Post by: 000_katie_000 on April 05, 2005, 10:38:29 AM

hello Ive tried everywhere to get the answers to these questions so I know if im doing them right and I'm running out of time to hand them in... please if you could help it would be greatly appreciated!!!

1. The antenna length for best reception of radio-frequency transmissions is normally half the wavelength of the signal being received. What antenna length (in m) is best suited for reception of a TV station that broadcasts at 232.7 MHz?

2. Calculate the smallest increment of energy (that is, the quantum of energy in J) that an object can absorb from light whose wavelength is 527nm?

3. A detector receives a 1.506e-16 J signal from photons whose wavelength is 569nm, how many photons were detected?

4. A hydrogen atom in its ground state absorbs a photon of wavelength 102.5 nm. To which higher energy state will it be excited?

Title: Re:Questions (quantum, frequency, wavelength...)
Post by: 000_katie_000 on April 06, 2005, 05:02:29 AM

OK well for proof that I have attempted them for question 1. my answer was 0.6446m - is this the correct answer? For question 2. my answer was 3.77e-19, is this correct? :S also for question 3. im really stuck because I keep getting a decimal for my answer.. my answer was 0.00232 is this possible..? And for the last question I also keep getting a decimal which i know cant be right... I use the equation: E= -RHZ2/n2
but my answer comes out totally wrong.

Title: Re:Questions (quantum, frequency, wavelength...)
Post by: Donaldson Tan on April 06, 2005, 11:57:34 AM

1. wavelength = speed of light / frequency

2. energy = hc/wavelength

3. energy of each photon (E) = hc/wavelength
    number of photons = 1.506x10^-16 / E

4. i cant remember bohr's equation off-hand