About \(5\)% of the power of a \(100\) W light bulb is converted to visible radiation. What is the average intensity of visible radiation at a distance of \(1\) m from the bulb?
1. \(0.472\) W/m²
2. \(0.398\) W/m²
3. \(0.323\) W/m²
4. \(0.401\) W/m²

Monochromatic light of wavelength \(632.8~\text{nm}\) is produced by a helium-neon laser. The power emitted is \(9.42~\text{mW}\). The energy of each photon in the light beam is:
1. \(4.801 \times 10^{-19}~\text{J}\)
2. \(2.121 \times 10^{-19}~\text{J}\)
3. \(5.043 \times 10^{-19}~\text{J}\)
4. \(3.141 \times 10^{-19}~\text{J}\)

The energy flux of sunlight reaching the surface of the earth is \(1.388\times10^{3}\) W/m². How many photons (nearly) per square meter are incident on the Earth per second? Assume an average wavelength of \(550~\text{nm}\).
1. \(3.84\times10^{21}\)
2. \(2.97\times10^{21}\)
3. \(4.12\times10^{21}\)
4. \(2.10\times10^{21}\)

A \(100\) W sodium lamp radiates energy uniformly in all directions. The lamp is located at the center of a large sphere that absorbs all the sodium light which is incident on it. The wavelength of sodium light is \(589\) nm. What is the energy per photon associated with the sodium light?
1. \( 1.21 \) eV
2. \( 2.21 \) eV
3. \( 2.11 \) eV
4. \( 1.11\) eV

In an accelerator experiment on high-energy collisions of electrons with positrons, a certain event is interpreted as the annihilation of an electron-positron pair of total energy 10.2 BeV into two γ-rays of equal energy. What is the wavelength associated with each γ-ray? (1BeV = 109 eV)

1.  \(3.4 \times10^{-16}\) m
2. \(1.7 \times10^{-16}\) m
3. \(2.4 \times10^{-16}\) m
4. \(3.1 \times10^{-16}\) m