AIEEE 2007 PYQ Mock Test

Which of the following transitions in hydrogen atoms emit photons of highest frequency?

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 $m$:

Two lenses of power $-15\text{D}$ and $+5\text{D}$ are in contact with each other. The focal length of the combination is:

One end of a thermally insulated rod is kept at a temperature $T_1$ and the other at $T_2$. The rod is composed of two sections of lengths $l_1$ and $l_2$ and thermal conductivities $k_1$ and $k_2$ respectively. The temperature at the interface of the two sections is:

A sound absorber attenuates the sound level by $20\text{dB}$. The intensity decreases by a factor of: