All India Engineering / Architecture Entrance Examination (AIEEE)
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AIEEE 2007 Physics
Q. 21. Which of the following transitions in hydrogen atoms emit photons of highest frequency?
- n = 2 to n = 6
- n = 6 to n = 2
- n = 2 to n = 1
- n = 1 to n = 2
Sol:
So photons of highest frequency will be emitted for n = 2 to n = 1
Correct choice: (3)
Q. 22. A block of mass m is connected to another block of mass M by a spring (massless) of spring constant k. The blocks are kept on a smooth horizontal plane. Initially the blocks are at rest and the spring is unstretched. Then a constant force F starts acting on the block of mass M to pull it. Find the force on the block of mass m
Sol: In the question the state of spring is not mentioned. We are assuming acceleration of both blocks to be same.
Correct choice: (3)
Q. 23. Two lenses of power –15 D and +5D are in contact with each other. The focal length of the combination is
- – 20 cm
- – 10 cm
- + 20 cm
- + 10 cm
Sol: 
Correct choice: (2)