# Worksheet: Blackbody Radiation and Photon Energy

In this worksheet, we will practice defining the electric flux through a surface due to an electric field and finding products of electric field and area vectors.

**Q1: **

Determine the power intensity of radiation per unit wavelength emitted at a wavelength of 500.0 nm by a blackbody at a temperature of K.

- A
W/m
^{3} - B
W/m
^{3} - C
W/m
^{3} - D
W/m
^{3} - E
W/m
^{3}

**Q2: **

A 200-W heater emits a 1.50- radiation. Radiation from the heater warms a 4.00-kg body by 2.00 K.

What value of the energy quantum does it emit?

Assuming that the specific heat capacity of the body is 0.83 kcal/kg⋅K, how many photons must be absorbed to warm the body?

- A
- B
- C
- D
- E

Assuming that all the radiation that the heater emits is absorbed by the body, how much time is required for the body’s temperature to increase?

**Q3: **

Lasers can be used as surgical instruments to vaporize flesh by heating it.
A carbon dioxide laser used in surgery emits infrared radiation with a wavelength of 10.6 μm.
In 1.00 ms,
this laser raised the temperature of 1.00 cm^{3}
of flesh to and evaporated it.
Flesh has a latent heat of vaporization of kJ/kg.

How many photons were required to vaporize the flesh?

- A
- B
- C
- D
- E

What was the minimum power output during the flash?

**Q4: **

A photon has the same energy as a proton that is moving at .

What is the wavelength of the photon?

What is the energy of the photon?

What is the kinetic energy of the proton?

**Q5: **

What is the minimum frequency of a photon required to ionize a ion in its first excited state if the energy required is 30.6 eV? Use a value of eV⋅s for the value of the Planck Constant.

- A Hz
- B Hz
- C Hz
- D Hz
- E Hz

**Q6: **

The tungsten elements of incandescent light bulbs operate at 700 K. At what frequency does the filament radiate maximum energy?

- A Hz
- B Hz
- C Hz
- D Hz
- E Hz

**Q8: **

The wavelengths of visible light range from approximately 390 nm to 770 nm. What is the corresponding range of photon energies for visible light?

- A J to J
- B J to J
- C J to J
- D J to J
- E J to J

**Q9: **

Calculate the temperature of the Sun, modeling the Sun as a black body emitting radiation at a maximum intensity at a wavelength of 0.500 micrometres.

**Q10: **

Calculate the heat flux emitted from the Sun’s surface, modeling the Sun as a black body emitting radiation at maximum intensity at a 0.50-micrometer wavelength.

- A
kW/m
^{2} - B
kW/m
^{2} - C
kW/m
^{2} - D
kW/m
^{2} - E
kW/m
^{2}

**Q11: **

In about five billion years, the Sun will evolve into a red giant. Assume that its surface temperature will decrease to about half its present value of K, while its present radius of m will increase to m, which is the current Earth-Sun distance. Calculate the ratio of the total power emitted by the Sun in its red giant stage to its present power.

**Q12: **

Treating the human body as a blackbody, determine the percentage increase in the total power of its radiation when its temperature increases from to .

- A4.95%
- B0.858%
- C0.683%
- D0.863%
- E4.82%

**Q13: **

The tungsten elements of incandescent light bulbs operate at 700 K. At what frequency does the filament radiate the most energy?

- A Hz
- B Hz
- C Hz
- D Hz
- E Hz