Which instrument is used to measure rain fall?

Which instrument is used to measure the level of humidity?

Which instrument is used to measure current in the circuit ? how is it connected in the circuit?

Which instrument is used to measure atmospheric pressure ?

A student measured the length of a rod and wrote it as 3.50 cm. Which instrument did he use to measure it ?

Which instrument is used to measure the intensity of light produced by an unknown source in terms of a standard source?