2) The temperature of a student\'s skin is 33.0°C. At what wavelength does the r

Question

2)The temperature of a student's skin is 33.0°C. At what wavelength does the radiation emitted from the skin reach its peak? (in µm)

(a) Assuming the Sun's surface emits as a black body, calculate its surface temperature. (in K)

(b) Using the result of part (a), find max for the Sun. (in nm)

4)

Calculate the energy of a photon having a wavelength in the following ranges.

(a) microwave, with = 60.00 cm (in eV)

(b) visible, with = 600 nm (in eV)

(c) x-ray, with = 0.60 nm (in eV)

5)The threshold of dark-adapted (scotopic) vision is 8.0 10-11 W/m2 at a central wavelength of 450 nm. If light with this intensity and wavelength enters the eye when the pupil is open to its maximum diameter of 9.0 mm, how many photons per second enter the eye? (in photons/s)

6)The work function for barium is 2.50 eV.

(a) Find the cutoff wavelength for barium. (in nm)

(b) What is the lowest frequency of light incident on barium that releases photoelectrons from its surface? (in Hz)

(c) If photons of energy 4.13 eV are incident on barium, what is the maximum kinetic energy of the ejected photoelectrons? (in eV)

7)When light of wavelength 254 nm falls on cesium, the required stopping potential is 3.00 V. If light of wavelength 436 nm is used, the stopping potential is 0.900 V. Use this information to plot a graph like that shown in the figure below.

From your graph, determine the cutoff frequency for cesium and its work function.

8)Two light sources are used in a photoelectric experiment to determine the work function for a particular metal surface. When green light from a mercury lamp ( = 546.1 nm) is used, a stopping potential of 0.754 V reduces the photocurrent to zero.

(a) Based on this measurement, what is the work function for this metal? (in eV)

(b) What stopping potential would be observed when using light from a red lamp ( = 686.0 nm)? (in V)

9)Calculate the minimum wavelength x-ray that can be produced when a target is struck by an electron that has been accelerated through each of the following potential differences.

(a) 12.0 kV
min = ______m

(b) 94 kV
min = _______m

10)What minimum accelerating voltage would be required to produce an x-ray with a wavelength of 0.0380 nm?

V = _________kV

Explanation / Answer

only 1 question at a time please:
1.
wein's displacement law is:
max * T = b

Here b = 2.9*10^-3 m-K
So,
max * T = 2.9*10^-3

a)
for lightning,
T = 9.8*10^3 K

max * T = 2.9*10^-3
max * (9.8*10^3) = 2.9*10^-3
max = 2.96*10^-7 m
= 296 nm
Answer: 296 nm

b)
for nuclear explosion,
T = 9.5*10^6 K

max * T = 2.9*10^-3
max * (9.5*10^6) = 2.9*10^-3
max = 3.05*10^-10 m
= 305 pm
Answer: 305 pm

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