KVPY SB SX Exam 2011 Question Paper

Question : 34 of 120

Marks: +1, -0

An electron collides with a free molecule initially in its ground state. The collision leaves the molecule in an excited state that is metastable and does not decay to the ground state by radiation. Let K be the sum of the initial kinetic energies of the electron and the molecule, and

P↖{→}

the sum of their initial momenta. Let K' and

P↖{→}'

represent the same physical quantities after the collision. Then

$K=K',P↖{→}= P↖{→}'$
$K> K',P↖{→}= P↖{→}'$
$K=K',P↖{→}≠ P↖{→}'$
$K>K',P↖{→}≠ P↖{→}'$

Validate

Solution:

Collision of

e^{–}

lead to excitation of molecules
so Collision is inelastic
∴ K' < K and loss of kinetic energy go for excitation of molecules. Momentum remain conserved during collision.

\P↖{→} = {\P'} ↖{→}

Go to Question:

Prev Question

Next Question