If $5\%$ of the energy supplied to a bulb is irradiated as visible light, how many quanta are emitted per sec by a $100$ $watt$ lamp ? Assume wavelength of visible light as $5.6\times10^{-5}\, cm$.
If $5\%$ of the energy supplied to a bulb is irradiated as visible light, how many quanta are emitted per sec by a $100$ $watt$ lamp ? Assume wavelength of visible light as $5.6\times10^{-5}\, cm$.
- A
$1.4\times10^{19}$
- B
$2.0\times10^{-4}$
- C
$1.4\times10^{-19}$
- D
$2.0\times10^{4}$
Similar Questions
Photoelectric effect experiments are performed using three different metal plates $\mathrm{p}, \mathrm{q}$ and $\mathrm{r}$ having work functions $\phi_p=2.0 \mathrm{eV}, \phi_q=2.5 \mathrm{eV}$ and $\phi_r=3.0 \mathrm{eV}$, respectively. A light beam containing wavelengths of $550 \mathrm{~nm}, 450 \mathrm{~nm}$ and $350 \mathrm{~nm}$ with equal intensities illuminates each of the plates. The correct I-V graph for the experiment is [Take $h c=1240 \mathrm{eV} \mathrm{nm}$ ]
Photoelectric effect experiments are performed using three different metal plates $\mathrm{p}, \mathrm{q}$ and $\mathrm{r}$ having work functions $\phi_p=2.0 \mathrm{eV}, \phi_q=2.5 \mathrm{eV}$ and $\phi_r=3.0 \mathrm{eV}$, respectively. A light beam containing wavelengths of $550 \mathrm{~nm}, 450 \mathrm{~nm}$ and $350 \mathrm{~nm}$ with equal intensities illuminates each of the plates. The correct I-V graph for the experiment is [Take $h c=1240 \mathrm{eV} \mathrm{nm}$ ]
- [IIT 2009]
Match the column
$(A)$ Hallwachs $\&$ Lenard
$(P)$ Transformers
$(B)$ Franck-Hertz
$(Q)$ Microwave
$(C)$ Klystron valve
$(R)$ Quantization of energy levels
$(D)$ Nicola Tesla
$(S)$ Photoelectric effect
Match the column
| $(A)$ Hallwachs $\&$ Lenard | $(P)$ Transformers |
| $(B)$ Franck-Hertz | $(Q)$ Microwave |
| $(C)$ Klystron valve | $(R)$ Quantization of energy levels |
| $(D)$ Nicola Tesla | $(S)$ Photoelectric effect |
A photon in motion has a mass
A photon in motion has a mass
Rest mass energy of an electron is $0.51\ MeV.$ If this electron is moving with a velocity $0.8\ c$ (where $c$ is velocity of light in vacuum), then kinetic energy of the electron should be. ........... $MeV$
Rest mass energy of an electron is $0.51\ MeV.$ If this electron is moving with a velocity $0.8\ c$ (where $c$ is velocity of light in vacuum), then kinetic energy of the electron should be. ........... $MeV$
A totally reflecting small plane mirror placed horizontally faces a parallel beam of light as hown in figure. The mass of mirror is $20\, gm$. Assume that there is no absorption in the lens and that $30\%$ of the light emitted by the source goes through the lens. Find the power of the source needed to support the weight of the mirror ............... $MW$ (take $g = 10\, m/s^2$) :-
A totally reflecting small plane mirror placed horizontally faces a parallel beam of light as hown in figure. The mass of mirror is $20\, gm$. Assume that there is no absorption in the lens and that $30\%$ of the light emitted by the source goes through the lens. Find the power of the source needed to support the weight of the mirror ............... $MW$ (take $g = 10\, m/s^2$) :-