Radiation thermometer can not measure the temperature

Inside a pressure vessel

Of an object without coming in contact with it

Of liquid oxygen

Answer

Of moving objects at high temperature

Answer: Option C

Solution

Answer: Option C

Solution:

The correct answer is A: Inside a pressure vessel.

Here's why:

A radiation thermometer works by detecting the infrared radiation emitted by an object.
This radiation travels through the air (or a vacuum) to the thermometer.

Option A: Inside a pressure vessel, the radiation thermometer cannot directly "see" the object whose temperature it needs to measure.
The vessel walls would block the radiation.
Think of it like trying to see something behind a solid wall – you can't!

Option B: Of an object without coming in contact with it is a key advantage of radiation thermometers; they measure temperature remotely.

Option C: Of liquid oxygen - Radiation thermometers *can* measure the temperature of liquid oxygen, even though it's very cold.
Everything emits some radiation.

Option D: Of moving objects at high temperature - Radiation thermometers are well-suited for measuring the temperature of hot, moving objects because they don't require physical contact.