ANS:A - rises in the tube.

As the fluid flow rate increases, the float of the rotameter rises in the tube. Explanation: A rotameter is a device used to measure the flow rate of a fluid in a closed conduit. It consists of a tapered tube with a float (usually a ball or a cylindrical shape) inside it. The float is free to move up and down the tube based on the flow rate of the fluid passing through it. When the fluid flow rate increases:

1. The velocity of the fluid passing through the tube increases.
2. This higher velocity exerts a greater force on the float, causing it to rise in the tube.
3. The float rises until the gravitational force acting on the float is balanced by the upward force exerted by the fluid flow.
4. The position of the float within the calibrated scale on the tube provides a visual indication of the flow rate of the fluid.