Calculate the temperature of and power-per-area radiated from a blackbody if the spectral intensity density peaks at (a) gamma rays, λ = 1.50×10−14 m; (b) x rays, 1.50 nm; (c) red light, 640 nm; (d) broadcast television waves, 1.00 m; and (e) AM radio waves, 204 m.

a)  T = 1,932 10¹¹ K ,  I = 7.90 10³⁷ W / m² ,

b)  T = 1,932 10⁶ K ,  I = 7.90 10¹⁷ W / m² ,

c)  T = 4,528 10³ K ,  I = 4.20 10⁶ W / m² ,

d)  T = 2,898 10⁻³ K ,  I = 4.0 10⁻¹⁰ W / m²

e)   T = 1.42 10⁻⁵ K , I= 4.07 10⁻²⁸ W / m²

Explanation:

For this exercise we can use Wien's displacement law and Stefan's law

          λ T = 2,898 10⁻³

         T = 2,898 10-3 / λ

         P = σ A e T⁴

         I = P / A = σ e T⁴

The value of the Stefan –Boltzmann (σ) constant is 5.670 10⁻⁸ W / m²K⁴, the emissivity (e) for a black body is  1

           I = σ T⁴

a) λ = 1.50 10⁻¹⁴ m

The temperature is

            T = 2,898 10⁻³ /λ

            T = 2,898 10⁻³ / 1.50 10⁻¹⁴

            T = 1,932 10¹¹ K

            I = 5,670 10⁻⁸ (1,932 10¹¹)⁴

            I = 7.90 10³⁷ W / m²

b) λ = 1.50 nm = 1.50 10⁻⁹ m

              T = 2,898 10⁻³ / 1.50 10⁻⁹

              T = 1,932 10⁶ K

              I = 5,670 10⁻⁸ (1,932 10⁶)⁴

              I = 7.90 10¹⁷ W / m²

c) λ = 640 nm = 6.40 10⁻⁷ m

              T = 2,898 10⁻³ / 6.40 10⁻⁷

              T = 4,528 10³ K

              I = 5,670 10⁻⁸ (4,528 10³)⁴

              I = 4.20 10⁶ W / m²

d) λ = 1.00 m

             T = 2,898 10⁻³ / 1

             T = 2,898 10⁻³ K

             I = 5,670 10⁻⁸ (2,898 10⁻³)⁴

             I = 4.0 10⁻¹⁰ W / m²

e) λ = 204 m

            T = 2,898 10⁻³ / 204

            T = 1.42 10⁻⁵ K

             I = 5,670 10⁻⁸ (1.42 10⁻⁵)⁴

             I = 4.07 10⁻²⁸ W / m²

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27

report!

explanation:

physics means: "the branch of science concerned with the nature and properties of matter and energy. the subject matter of physics, distinguished from that of chemistry and biology, includes mechanics, heat, light and other radiation, sound, electricity, magnetism, and the structure of atoms."