एक प्रकाश-संवेदी पदार्थ का कार्य फलन 4.0 eV है। प्रकाश की वह अधिकतम तरंगदैर्घ्य जो इस पदार्थ से फोटोइलेक्ट्रॉन उत्सर्जन का कारण बन सकती है, लगभग कितनी है?

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)