What is the instrument used to measure the electric potential difference between two points called?

What is the instrument used to measure the magnetic field of Earth called?

Which instrument is used to measure the intensity of ultraviolet radiation?

Which instrument is used to measure the concentration of ions in a solution?

Which instrument is used to measure the velocity of an object?

Which instrument is used to measure the moisture content in the air?

What is the instrument used to measure the electric charge called?

What is the instrument used to measure the blood pressure called?

Which instrument is used to measure the speed of an object underwater?

What is the instrument used to measure the concentration of oxygen in a gas mixture?