Find the number of photons emitted per second by a 25 W source of monochromatic light of wavelength `6600 Å`. What is the photoelectric current assuming 3% efficiency for photoelectric effect. Given `h = 6.6 xx 10^(-34) Js`.
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If a light with frequency `4xx10^(16) Hz` emitted photoelectrons with double the maximum kinetic as are emitted by the light of frequency `2.5xx10^(16
Correct Answer - `1xx10^(16) Hz` For frequency `2.5xx10^(16) Hz, h v=hv_(o)+KE_(max)` `:. h(2.5xx10^(16))=hv_(o)+KE_(max) ...(i)` For frequency `4xx10^(16)` Hz, `h(4xx10^(16))=hv_(o)+2KE_(max) ...(2)` Multiply `eq^(n)` (1) by `2` and substract `eq^(n)` (2) from it....
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A bulb of 40 W is producing a light of wavelength 620 nm with `80%` of efficiency , then the number of photons emitted by the bulb in 20 seconds are :
Correct Answer - D Power`=(nhC)/(lambdaxxt) rArr 40xx80/100=(nxx6.62xx10^(-34)xx3xx10^(8))/(620xx10^(-9)xx20) rArr n=2xx10^(21)`
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Calculate the number of photons emitted by a `100 W` yellow lamp in `1.0 s`. Take the wavelength of yellow light as `560 nm` and assume `100` percent
Correct Answer - 4 The number pf photon is `N=E/(hv)=(PDeltat)/(h(c//lambda))=(lambdaPDeltat)/(hc)` Substitution of the data gives `N=((5.60xx10^(-7)m)xx(100Js^(-1))xx(1.0s))/((6.626xx10^(-36)s)xx(3xx10^(8)ms^(-1)))=2.8xx10^(20)`
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A photo sensitive surface is receiving light of wavelength `5000Å` at the rate of `10^(-7)J//s`. The number of photons received per second is : (Given
Correct Answer - B `E=n(hc)/(lambda)` `10^(-7)= (nxx(6.626 xx 10^(-34)Js)(3xx 10^(8) m//s))/(5000xx10^(-10)m)` ` n = 2.5 xx 10^(11)` photons per second
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In Young’s double slit experiment a monochromatic light of wavelength` lambda` from a distant point source is inci- dent upon the two identical slits.
Correct Answer - (a)`4I_(0)cos^(2)((pi)/(3)+(pi)/(lambda)(mu-1)t)` (b)`t=((2n-1)lambda)/(2(mu-1))-(lambda)/(3(mu-1))"wheren=1,2,3...`
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A `0.6 xx 10^(-3) W` laser is aimed at the Moon. The wavelength of emitted light is 600 nm and the laser beam spreads out of the source at a divergenc
Correct Answer - `5.7 xx 10^(4) m^(-2) s^(-1)`
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A normal human eye can detect yellow light if more than 10 photons enter into it per second. A star is generating as much power as the Sun and is emit
Correct Answer - `1.64 xx 10^(19) m`
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A 220V electric kettle takes 990W. Calculate (i) the resistance of the heating element, (ii) the time required to melt and boil away 1kg of ice assumi
Correct Answer - 1.414hour,`49Omega`
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Photoelectric work function for a surface is 2.4 eV. Light of wavelength `6.8 xx 10^(-7)`m shines on the surface. Find the frequency of incident light
Correct Answer - `v =4.41 xx 10^(14)Hz,v_(0)=5.82 xx 10^(14) Hz`, no photoelectric emission occurs as `v lt v_(0)`
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The photoelectric threshold wavelength for lithium is `8000 Å`. Find the maximum kinetic energy in eV of the emitted electrons from the surface by lig
Correct Answer - 0.5156 eV
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