Hertz and Lenard's Observations NEET Questions

Physics - Dual Nature of Matter and Radiation

Hertz and Lenard's Observations MCQ Questions


13.
In which year did Hallwachs perform his pioneering electroscope experiment with the zinc plate?
A.
1905
B.
1879
C.
1897
D.
1888
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ANSWER :
D. 1888
14.
Hallwachs and Lenard investigated the phenomenon of photoelectric emission in detail during:
A.
1897-1905
B.
1879-1888
C.
1886-1902
D.
1905-1916
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ANSWER :
C. 1886-1902
15.
Philipp Lenard's observation in his evacuated glass tube experiment showed that:
A.
Current flowed only when X-rays were used
B.
Current flowed only when the tube was filled with gas
C.
Current flowed in the circuit when UV light fell on the emitter plate
D.
No current flowed regardless of light
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ANSWER :
C. Current flowed in the circuit when UV light fell on the emitter plate
16.
In Lenard's experiment, when the ultraviolet radiations were stopped:
A.
The voltage across the tube increased
B.
The current continued to flow due to inertia
C.
The current flow stopped immediately
D.
The current reversed direction
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ANSWER :
C. The current flow stopped immediately
17.
In Lenard's evacuated glass tube setup, the emitter plate is conventionally labelled:
A.
G (Gate)
B.
S (Source)
C.
A (Anode)
D.
C (Cathode)
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ANSWER :
D. C (Cathode)
18.
In a photoelectric experiment, the tube must be evacuated because:
A.
Light cannot travel through gas
B.
Gas molecules would scatter and impede the photoelectrons
C.
Gas would absorb all UV radiation
D.
The metal plates would oxidize quickly in air
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ANSWER :
B. Gas molecules would scatter and impede the photoelectrons