Question

The glass tube in simple barometer is

• A. Open at both ends
• B. Close at one end
• C. Close at both ends
• D. None

Answer 1

The correct option is B Close at one end

A simple barometer or a mercury barometer is shown in the figure. It has a glass tube closed at one end with an open mercury-filled reservoir at the base. The weight of the mercury creates a vacuum in the top of the tube known as Torricellian vacuum. Mercury in the tube adjusts until the weight of the mercury column balances the atmospheric force exerted on the reservoir. High atmospheric pressure places more force on the reservoir, forcing mercury higher in the column. Low pressure allows the mercury to drop to a lower level in the column by lowering the force placed on the reservoir.