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Medical
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The potential difference that must be applied to stop the fastest photoelectrons emitted by a nickel surface, having work function 5.01 eV, when ultraviolet light of 200 nm falls on it, must be:

• Option 1)

2.4 V

• Option 2)

-1.2 V

• Option 3)

-2.4 V

• Option 4)

1.2 V

As we discussed in concept Conservation of energy -   - wherein     Stopping Potential /Cut-off Potential - It is defined as the potential necessary to stop any electron from reaching the other side. -           Option 1) 2.4 V This option is incorrect. Option 2) -1.2 V This option is incorrect. Option 3) -2.4 V This option is incorrect. Option 4) 1.2 V This option is correct.
Medical
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A source $S_{1}$ is producing, $10^{15}$ photons per second of wavelength 5000 $A^{\circ}$. Another source $S_{2}$ is producing $1.02\times 10^{15}$ photons per second of wavelength 5100 $A^{\circ}$ Then, (power of $S_{2}$) (power of $S_{1}$) is equal to:

• Option 1)

1.00

• Option 2)

1.02

• Option 3)

1.04

• Option 4)

0.98

As we discussed in concept photon - A packet or bundle of energy is called a photon -    and Energy of a photon - - wherein    Power =        Option 1) 1.00 This option is correct. Option 2) 1.02 This option is incorrect. Option 3) 1.04 This option is incorrect. Option 4) 0.98 This option is incorrect.
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