In body Plethysmography, a person is asked to expire against a closed glottis. Whiat will be the change in the pressure in the lung and the box

C i.e. Increase in lung decrease in boxBecause of Boyle's law (P1V1 = P2V2), during expiration when lung volume decreases, the pressure inside the lung increases and pressure inside the air tight box decreases because the gas volume in box increases - in body plethysmography in which the subject sits in an air tight chamber.