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When a monochromatic point source of light is at a distance of 0.2 m from a photoelectric cell, the cut off voltage and the saturation current are respectively 0.6 volt and 18.0 mA. If the same source is placed 0.6 m away from the photoelectric cell, then find
Q.
the saturation current
Correct answer is '2.0'. Can you explain this answer?
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Verified Answer
When a monochromatic point source of light is at a distance of 0.2 m f...
Intensity of photons ↑, no. of electron ↑
The cut off voltage does not depend on distance between cell and source.
But intensity is inversely proportional to square of it's distance.
∴ at d=0.6m,
Cut off voltage =0.6V
but
Is=18×(0.2/0.6)2
=2mA
So, the answers are option 2.0 mA
The cut off voltage does not depend on distance between cell and source.
But intensity is inversely proportional to square of it's distance.
∴ at d=0.6m,
Cut off voltage =0.6V
but
Is=18×(0.2/0.6)2
=2mA
So, the answers are option 2.0 mA
Most Upvoted Answer
When a monochromatic point source of light is at a distance of 0.2 m f...
Given:
To find:
Saturation current, I2
Formula:
The formula for photoelectric current is given by:
I = I0 (1 - e-eV/kT)
where,
I = photoelectric current
I0 = saturation current
e = charge on an electron
V = stopping potential
k = Boltzmann’s constant
T = temperature of the metal surface
Calculation:
Let us assume that the work function of the metal surface is constant.
Therefore, we can write the formula for saturation current as:
I0 = I (1 - e-ed/kT)
where, e and k are constants.
Now, we know that the saturation current, I0 is constant for a given photoelectric cell.
Therefore, we can equate the two formulas for saturation current at two different distances:
I0 = I2 (1 - e-ed2/kT)
I0 = I (1 - e-ed1/kT)
Dividing the two equations, we get:
I2/I = (1 - e-ed2/kT) / (1 - e-ed1/kT)
Substituting the given values, we get:
I2/18.0 x 10-3 = (1 - e-0.6d2/kT) / (1 - e-0.6d1/kT)
Solving for I2, we get:
I2 = 2.0 x 10-3 A
Therefore, the saturation current when the source is placed 0.6 m away from the photoelectric cell is 2.0 mA.
- Distance between monochromatic point source of light and photoelectric cell, d1 = 0.2 m
- Cut off voltage, V0 = 0.6 V
- Saturation current, I0 = 18.0 mA = 18.0 x 10-3 A
- New distance between source and cell, d2 = 0.6 m
To find:
Saturation current, I2
Formula:
The formula for photoelectric current is given by:
I = I0 (1 - e-eV/kT)
where,
I = photoelectric current
I0 = saturation current
e = charge on an electron
V = stopping potential
k = Boltzmann’s constant
T = temperature of the metal surface
Calculation:
Let us assume that the work function of the metal surface is constant.
Therefore, we can write the formula for saturation current as:
I0 = I (1 - e-ed/kT)
where, e and k are constants.
Now, we know that the saturation current, I0 is constant for a given photoelectric cell.
Therefore, we can equate the two formulas for saturation current at two different distances:
I0 = I2 (1 - e-ed2/kT)
I0 = I (1 - e-ed1/kT)
Dividing the two equations, we get:
I2/I = (1 - e-ed2/kT) / (1 - e-ed1/kT)
Substituting the given values, we get:
I2/18.0 x 10-3 = (1 - e-0.6d2/kT) / (1 - e-0.6d1/kT)
Solving for I2, we get:
I2 = 2.0 x 10-3 A
Therefore, the saturation current when the source is placed 0.6 m away from the photoelectric cell is 2.0 mA.
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Community Answer
When a monochromatic point source of light is at a distance of 0.2 m f...
Cut off voltage is independent of intensity and hence remains the same.
Since distance becomes 3 times, so intensity decreases
= 1/9
Hence saturation current also decreases by this factor.
= 18/9
= 2mA
Since distance becomes 3 times, so intensity decreases
= 1/9
Hence saturation current also decreases by this factor.
= 18/9
= 2mA
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When a monochromatic point source of light is at a distance of 0.2 m from a photoelectric cell, the cut off voltage and the saturation current are respectively 0.6 volt and 18.0 mA. If the same source is placed 0.6 m away from the photoelectric cell, then findQ.the saturation currentCorrect answer is '2.0'. Can you explain this answer?
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When a monochromatic point source of light is at a distance of 0.2 m from a photoelectric cell, the cut off voltage and the saturation current are respectively 0.6 volt and 18.0 mA. If the same source is placed 0.6 m away from the photoelectric cell, then findQ.the saturation currentCorrect answer is '2.0'. Can you explain this answer? for Class 12 2024 is part of Class 12 preparation. The Question and answers have been prepared according to the Class 12 exam syllabus. Information about When a monochromatic point source of light is at a distance of 0.2 m from a photoelectric cell, the cut off voltage and the saturation current are respectively 0.6 volt and 18.0 mA. If the same source is placed 0.6 m away from the photoelectric cell, then findQ.the saturation currentCorrect answer is '2.0'. Can you explain this answer? covers all topics & solutions for Class 12 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for When a monochromatic point source of light is at a distance of 0.2 m from a photoelectric cell, the cut off voltage and the saturation current are respectively 0.6 volt and 18.0 mA. If the same source is placed 0.6 m away from the photoelectric cell, then findQ.the saturation currentCorrect answer is '2.0'. Can you explain this answer?.
When a monochromatic point source of light is at a distance of 0.2 m from a photoelectric cell, the cut off voltage and the saturation current are respectively 0.6 volt and 18.0 mA. If the same source is placed 0.6 m away from the photoelectric cell, then findQ.the saturation currentCorrect answer is '2.0'. Can you explain this answer? for Class 12 2024 is part of Class 12 preparation. The Question and answers have been prepared according to the Class 12 exam syllabus. Information about When a monochromatic point source of light is at a distance of 0.2 m from a photoelectric cell, the cut off voltage and the saturation current are respectively 0.6 volt and 18.0 mA. If the same source is placed 0.6 m away from the photoelectric cell, then findQ.the saturation currentCorrect answer is '2.0'. Can you explain this answer? covers all topics & solutions for Class 12 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for When a monochromatic point source of light is at a distance of 0.2 m from a photoelectric cell, the cut off voltage and the saturation current are respectively 0.6 volt and 18.0 mA. If the same source is placed 0.6 m away from the photoelectric cell, then findQ.the saturation currentCorrect answer is '2.0'. Can you explain this answer?.
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When a monochromatic point source of light is at a distance of 0.2 m from a photoelectric cell, the cut off voltage and the saturation current are respectively 0.6 volt and 18.0 mA. If the same source is placed 0.6 m away from the photoelectric cell, then findQ.the saturation currentCorrect answer is '2.0'. Can you explain this answer?, a detailed solution for When a monochromatic point source of light is at a distance of 0.2 m from a photoelectric cell, the cut off voltage and the saturation current are respectively 0.6 volt and 18.0 mA. If the same source is placed 0.6 m away from the photoelectric cell, then findQ.the saturation currentCorrect answer is '2.0'. Can you explain this answer? has been provided alongside types of When a monochromatic point source of light is at a distance of 0.2 m from a photoelectric cell, the cut off voltage and the saturation current are respectively 0.6 volt and 18.0 mA. If the same source is placed 0.6 m away from the photoelectric cell, then findQ.the saturation currentCorrect answer is '2.0'. Can you explain this answer? theory, EduRev gives you an
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