ABCDEFGH is a hollow cube made of an insulator (Fig). Face ABCD has positive charge on it. Inside the cube, we have ionized hydrogen. The usual kinetic theory expression for pressure
(a) Will be valid.
(b) Will not be valid since the ions would experience forces other than due to collisions with the walls.
(c) Will not be valid since collisions with walls would not be elastic.
This is a multiple choice answer as classified in NCERT Exemplar
(b), (d) due to the presence of external positive charge on face ABCD. The usual expression for pressure on the basis of kinetic energy will not be valid as ions would also experience electrostatic force. So presence of positive charge
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