दो धातु की सतहों A और B के कार्य फलन (work functions) क्रमशः φA = 9 eV और φB = 4.5 eV हैं। इन दोनों धातु की सतहों की देहली तरंगदैर्ध्य (threshold wavelengths) का अंतर (λB - λA) नैनोमीटर (nm) में कितना होगा? (दिया गया है, hc = 1242 eV nm)

A bulb is rated at 150 W and converts 8% of its input energy into light. If the energy of one photon is 4.42 × 10-19 J, how many photons are emitted by the bulb per second?

For a metal with a work function of 6.6 eV, which of the following wavelengths of incident radiation will NOT cause the photoelectric effect? (Take Planck's constant h = 6.6 × 10-34 J s and c = 3 × 108 m/s)