An experimental setup of verification of photoelectric effect is shown in the diagram. The voltage across the electrode is measured with the help of an ideal voltmetar, and which can be varied by moving jockey `'J'` on the potentiometer wire. The battery used in potentiometer circuit is of 20 V and its internal resistance is `2omega`. The resistance of `100 cm` long potentiometer wire is `8 omega`. The photo current is measured with the help of an ideal ammeter. Two plates of potassium oxide of area `50 cm^(2)` at separation `0.5 mm` are used in the vacuum tube. Photo current in the circuit is very small so we can treat potentiometer circuit an indepdent circuit. The wavelength of various colours is as follows :
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`|{:("Light",underset("Violet")(1),underset("Blue")(2),underset("Green")(3),underset("Yellow")(4),underset("Orange")(5),underset("Red")(6)),(lambda "in" Årarr,4000-4500,4500-5000,5000-5500,5500-6000,6000-6500,6500-7000):}|`
It is found that ammeter current remians unchanged `(2muA)` even when the jockey is moved from the `'P'` to the middle point of the potentiometer wire. Assuming all the incident photons eject electron and the power of the light incident is `4 xx 10^(-6) W`. Then colour of the incident light is :
An experimental setup of verification of photoelectric effect is shown in the diagram. The voltage across the electrode is measured with the help of an ideal voltmetar, and which can be varied by moving jockey `'J'` on the potentiometer wire. The battery used in potentiometer circuit is of 20 V and its internal resistance is `2omega`. The resistance of `100 cm` long potentiometer wire is `8 omega`. The photo current is measured with the help of an ideal ammeter. Two plates of potassium oxide of area `50 cm^(2)` at separation `0.5 mm` are used in the vacuum tube. Photo current in the circuit is very small so we can treat potentiometer circuit an indepdent circuit. The wavelength of various colours is as follows :
`|{:("Light",underset("Violet")(1),underset("Blue")(2),underset("Green")(3),underset("Yellow")(4),underset("Orange")(5),underset("Red")(6)),(lambda "in" Årarr,4000-4500,4500-5000,5000-5500,5500-6000,6000-6500,6500-7000):}|`
It is found that ammeter current remians unchanged `(2muA)` even when the jockey is moved from the `'P'` to the middle point of the potentiometer wire. Assuming all the incident photons eject electron and the power of the light incident is `4 xx 10^(-6) W`. Then colour of the incident light is :
`|{:("Light",underset("Violet")(1),underset("Blue")(2),underset("Green")(3),underset("Yellow")(4),underset("Orange")(5),underset("Red")(6)),(lambda "in" Årarr,4000-4500,4500-5000,5000-5500,5500-6000,6000-6500,6500-7000):}|`
It is found that ammeter current remians unchanged `(2muA)` even when the jockey is moved from the `'P'` to the middle point of the potentiometer wire. Assuming all the incident photons eject electron and the power of the light incident is `4 xx 10^(-6) W`. Then colour of the incident light is :
A
Green
B
Violet
C
Red
D
Orange
Text Solution
Verified by Experts
The correct Answer is:
D
`P=(nhc)/(lambda)` where n= number of photons incident per unit time. Also `I= n eimplies P=(Ihc)/(e lambda)`
`lambda=((2xx10^(-6))(6.6xx10^(-34))(3xx10^(8)))/((4xx10^(-6))(1.6xx10^(-19)))`
`=9.9/1.6xx10^(-7) m=9900/1.6 Å=6187 Å`
Which came in the range of orange light.
`lambda=((2xx10^(-6))(6.6xx10^(-34))(3xx10^(8)))/((4xx10^(-6))(1.6xx10^(-19)))`
`=9.9/1.6xx10^(-7) m=9900/1.6 Å=6187 Å`
Which came in the range of orange light.
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An experimental setup of verification of photoelectric effect is shown in the diagram. The voltage across the electrodes is measured with the help of an ideal voltmeter, and which can be varied by moving jockey 'j' on the potentiometer wire. The battery used in potentiometer circuit is of 20 V and its internal resistance is 2 Omega . The resistance of 100 cm long potentiometer wire is 8 Omega The photocurrent is measured with the help of an ideal ammeter. Two plates of potassium oxide of area 50 cm^(2) at separation 0.5 mm are used in the vacuum tube. Photo current in the circuit is very small so we can treat potentiometer circuit an independent circuit. The wavelengths of various colours is as follows : {:("Light",underset("Violet")(1),underset("Blue")(2),underset("Green")(3),underset("Yellow")(4),underset("Orange")(5),underset("Red")(6)),(lamda "in" Å rarr,4000-4500,4500-5000,5000-5500,5500-6000,6000-65000,6500-70000):} . It is found that ammeter current remains unchanged (2 muA) even when the jockey is moved from the end 'P' to the middle point of the potentiometer wire. Assuming all the incident photons eject electron and the power of the light incident is 4 xx 10^(-6) W . Then the colour of the incident light is
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