Fisica

Ejercicios de fisica Moderna

1) The temperature of your skin is approximately 35°C. What is the wavelength at which the peak occurs in the radiation emitted from your skin?

2) A 2.0-kg mass isattached to a mass less spring of force constant k =25 N/m. The spring is stretched 0.40 m from its equilibrium position and released. (a) Find the total energy and frequency of oscillation accordingto classical calculations. (b) Assume that the energy is quantized and find the quantum number, n, for the system. (c) How much energy would be carried away in a 1-quantum change?

3) (a) UseStefan’s law to calculate the total power radiated per unit area by a tungsten filament at a temperature of 3000 K. (Assume that the filament is an ideal radiator.) (b) If the tungsten filament of a lightbulb is rated at 75 W, what is the surface area of the filament? (Assume that the main energy loss is due to radiation.)


Light Quantization and the Photoelectric Effect

1) Calculate theenergy of a photon whose frequency is
(a) 5x1014 Hz, (b) 10 GHz, (c) 30 MHz. Express your answers in electron volts.

2) The average power generated by the Sun has the value 3.74x1026 W. Assuming theaverage wavelength of the Sun’s radiation to be 500 nm, find the number of photons emitted by the Sun in 1 s.

3) The photocurrent of a photocell is cut off by a retarding potential of 2.92 V forradiation of wavelength 250 nm. Find the work function for the material.

4) Molybdenum has a work function of 4.2 eV. (a) Find the cutoff wavelength and threshold frequency for the photoelectriceffect. (b) Calculate the stopping potential if the incident light has a wavelength of 200 nm.

5)
¿Cuáles son las frecuencias de los fotones que tienen las siguientes energías?
a) 1eV,
b) 1 keVc) 1 MeV.
6) Encontrar la energía de los fotones que tienen las siguientes longitudes de onda:
a) 450 nm,
b) 550 nm
c) 650 nm.


7) Justificar si es verdadero o falso, que en el...