Concepts Of Physics MCQ Edition [Volume 2]PhysicsPhotoelectric Effect and Wave–Particle Duality
Suppose n_r and n_b represent the number of photons emitted by a red bulb and a blue bulb respectively, both having equal power, during a given time interval. Which of the following is true?
Options
- An_r = n_b
- Bn_r < n_b
- CThe given information is insufficient to establish a relation between n_r and n_b
- Dn_r > n_b
Correct answer
D. n_r > n_b
Step-by-step solution
The energy of a single photon is given by E = hc , where h is Planck's constant, c is the speed of light, and is the wavelength. The total energy emitted by a bulb of power P in time interval t is E_ total = P t . The number of photons emitted in time t is n = E_ total E = P t hc . Since the power P and time interval t are the same for both bulbs, the number of photons emitted is directly proportional to the wavelength of the light, i.e., n . The wavelength of red light is greater than the wavelength of blue light