Which of the following statements best describes a laser
A: A device for stimulating atoms and molecules to emit light.
B: An atom in a high-energy state.
C: A technique for destroying atoms or molecules.
D: An instrument for measuring light waves.
A: A device for stimulating atoms and molecules to emit light.
B: An atom in a high-energy state.
C: A technique for destroying atoms or molecules.
D: An instrument for measuring light waves.
举一反三
- A laser can be best described by______. A: a device for stimulating atoms and molecules to emit light B: an atom in a high energy state C: a technique for destroying atom or molecules D: an instrument for measuring light waves
- Which of the following statements belong to Einstein's achievements in physics? A: It was proved that atoms and molecules existed. B: Light came in little bits (or photons) C: Space and time, like threads in a common fabric,could be bent, stretched and twisted. D: E=mc²
- Which is NOT the correct description about Laser? A: It stands for Light Amplification by Stimulated Emission. B: It’s a beam of light energy. C: All the light waves in a laser are emitted in the same rhythm. D: The light waves in a laser are of different wavelengths.
- After the atoms absorb energy, they can achieve a transition from a low energy level to a high energy level.
- 中国大学MOOC: Analysis of its spectrum can tell not only __________ atoms or molecules a substance is composed, but ___________ relative amounts they are present.