Question

If 5% of the energy supplied to a bulb is radiated as visible light, the number of visible quanta emitted per second by a 100 W bulb, assuming the wavelength of visible light to be 5.6 × 10⁻⁵ cm, is(a) 1.4 × 10⁹(b) 1.4 × 10²⁰(c) 2 × 10¹⁹(d) 2 × 10²⁰

Answer 1

d) 2 × 10²⁰

Hola

Thanks

Answer 2

Answer:

Explanation:

Bulb = 100W

λ= 5600 A

Energy of one photon is E = hV = h*c/ λ

E = 6.63* 10^-34×3 ×10^8/(5600* 10^-10)

= 3.616 * 10^-19 J

A 100 watt bulb requires 100 joule of energy per second.

Thus, the energy radiated by the bulb as visible light per second = 5% of 100

= 5 Joule

 Number of photons emitted per second =  Energy radiated per sec/ energy of one ohoton

= 5/(3.616×10^ -19)  

= 1.38 ×10^19