Advertisements
Advertisements
प्रश्न
A 150 W lamp emits light of the mean wavelength of 5500 Å. If the efficiency is 12%, find out the number of photons emitted by the lamp in one second.
Advertisements
उत्तर
P = 150 W
λ = 5500 × 10−10 m
Efficiency = 12%
N = `("P"λ)/"hc"`
= `(150 xx 5500 xx 10^-10)/(6.626 xx 10^-34 xx 3 xx 10^8)`
= `(825 xx 10^-7)/(19.878 xx 10^-26)`
= 41.5 × 1019
Number of photons emitted is with 12% efficiency = `41.5 xx 10^19 xx 12/100`
N = 4.98 × 1019
APPEARS IN
संबंधित प्रश्न
The work function of caesium metal is 2.14 eV. When light of frequency 6 × 1014 Hz is incident on the metal surface, photoemission of electrons occurs. What is the
- maximum kinetic energy of the emitted electrons,
- Stopping potential, and
- maximum speed of the emitted photoelectrons?
How does one explain the emission of electrons from a photosensitive surface with the help of Einstein's photoelectric equation?
How will the thermionic current vary if the filament current is increased?
Would you prefer a material with a high melting point or a low melting point to be used as a cathode in a diode?
The cathode of a diode valve is replaced by another cathode of double the surface area. Keeping the voltage and temperature conditions the same, will the place current decrease, increase or remain the same?
Let i0 be the thermionic current from a metal surface when the absolute temperature of the surface is T0. The temperature is slowly increased and the thermionic current is measured as a function of temperature. Which of the following plots may represent the variation in (i/i0) against (T/T0)?
Define the term "Threshold frequency", in the context of photoelectric emission.
If a light of wavelength 330 nm is incident on a metal with work function 3.55 eV, the electrons are emitted. Then the wavelength of the wave associated with the emitted electron is (Take h = 6.6 × 10–34 Js)
What do you mean by electron emission? Explain briefly various methods of electron emission.
Consider Figure for photoemission.
How would you reconcile with momentum conservation? Note light (photons) have momentum in a different direction than the emitted electrons.
