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In photoelectric effect light of certain...

In photoelectric effect light of certain frequency `( gt ` threshold frequency ) is incident on a metal surfave whereby , an `e^(-)` ( with certain K.E.) moves towards the collector plate and a flow of current is initiated . In order to stop the current flow, an opposite potential , on the two metal plates, is applied
The work function of metal is 6eV . If light of frequency ` 1 xx 10^(15) `Hz is incident on the metal , intensity of light is increased 4 times, then

A

No photoelectron will be ejected

B

8 photoelectrons of zero kinetic energy shall be ejected

C

2 photoelectrons of 2 eV kinetic energy are ejected

D

Only one photoelectron is ejected

Text Solution

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The correct Answer is:
To solve the problem regarding the photoelectric effect, we will follow these steps: ### Step 1: Understand the given data - Work function (φ) of the metal = 6 eV - Frequency of the incident light (ν) = 1 x 10^15 Hz - Intensity of light is increased 4 times. ### Step 2: Convert the work function from eV to Joules The work function in Joules can be calculated using the conversion factor: 1 eV = 1.6 x 10^-19 Joules. So, \[ \phi = 6 \, \text{eV} \times 1.6 \times 10^{-19} \, \text{J/eV} = 9.6 \times 10^{-19} \, \text{J} \] ### Step 3: Calculate the threshold frequency (ν₀) The work function is related to the threshold frequency by the equation: \[ \phi = h \nu_0 \] where \(h\) (Planck's constant) = 6.63 x 10^-34 J·s. Rearranging the equation gives: \[ \nu_0 = \frac{\phi}{h} = \frac{9.6 \times 10^{-19} \, \text{J}}{6.63 \times 10^{-34} \, \text{J·s}} \] Calculating this gives: \[ \nu_0 \approx 1.44 \times 10^{15} \, \text{Hz} \] ### Step 4: Compare the incident frequency with the threshold frequency - Incident frequency (ν) = 1 x 10^15 Hz - Threshold frequency (ν₀) = 1.44 x 10^15 Hz Since the incident frequency (1 x 10^15 Hz) is less than the threshold frequency (1.44 x 10^15 Hz), no electrons will be emitted from the metal surface. ### Step 5: Conclusion Even if the intensity of light is increased by 4 times, it does not affect the emission of electrons because the frequency of the incident light is still below the threshold frequency. Therefore, the correct answer is: **No photoelectrons will be ejected.**
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