In the case of a laser such as a neon laser, the atoms in the active medium emit light waves that have which of the following combined characteristics?

Introduction / Context:
Lasers are special light sources that produce very pure and organised light compared with ordinary lamps. The word LASER stands for Light Amplification by Stimulated Emission of Radiation. Examination questions often test conceptual understanding of what makes laser light unique, including properties such as monochromaticity and coherence.

Given Data / Assumptions:

• The device mentioned is a laser, such as a neon laser.

• The question asks about the nature of light waves emitted by atoms in the active medium.

• Options include same frequency, same amplitude, same phase and all of the above, plus one extra distractor.

• The learner is expected to know the key properties of laser light.

Concept / Approach:
Laser light is characterised by being monochromatic (single frequency or wavelength), coherent (constant phase relationship) and highly directional with nearly uniform amplitude in the beam. When atoms in the laser medium undergo stimulated emission, they emit photons that are in step with the stimulating photon, having the same energy (frequency), phase and direction. The intensity is built up through many such identical emissions, leading to a beam with very regular properties, which supports the choice all of the above.

Step-by-Step Solution:
Step 1: Recall that in stimulated emission, an incoming photon causes an excited atom to emit a second photon identical to the first. Step 2: Understand that identical here means same frequency (or wavelength) and same energy. Step 3: Recognise that the emitted photon is also in phase with the stimulating photon, giving rise to coherent light. Step 4: In a well aligned laser cavity, the photons also travel in nearly the same direction with similar amplitude profile. Step 5: Conclude that the options same frequency, same amplitude and same phase are all true for the idealised description of laser light, so the best answer is all of the above.

Verification / Alternative check:
Physics textbooks and laser technology references emphasise that laser light is monochromatic, coherent and highly directional. Diagrams show atoms undergoing stimulated emission, with emitted photons drawn as parallel, same colour waves in phase. These features together distinguish laser light from ordinary light sources, where photons are emitted randomly in direction, phase and often in a range of frequencies. This consistent description across many references supports the all of the above choice in such conceptual questions.

Why Other Options Are Wrong:
Choosing only same frequency would acknowledge monochromaticity but ignore coherence and directionality, which are just as important for understanding lasers. Similarly, selecting only same amplitude or only same phase would capture only a part of the description. The option same direction only misses the frequency and phase aspects entirely. Since the question is clearly about the combined properties of laser emission, these single property options are incomplete and therefore not the best answer.

Common Pitfalls:
Some candidates hesitate to choose all of the above because they are unsure about amplitude or phase relationships in detail. Others may over simplify and think that only frequency matters. To avoid such confusion, it is useful to memorise that laser beams are monochromatic, coherent and highly directional simultaneously. Whenever a multiple choice question lists these three properties together regarding ideal laser light, all of the above is usually the intended correct answer.

Final Answer:
In a laser, atoms emit light waves that have the same frequency, similar amplitude and the same phase, so the correct option is all of the above.