Question

Splitting of spectral lines under the influence of magnetic field is called (a) Stark effect (b) Zeeman effect (c) photoelectric effect (d) screening effect.

Short answer

The splitting of spectral lines under the influence of a magnetic field is called the Zeeman effect.

Step-by-step solution

Understanding the Question

The task is to identify the correct term that describes the splitting of spectral lines when a magnetic field is applied to an atom. This is a conceptual question regarding well-known physical effects.

Recalling the Definitions

To answer the question, recall the definitions of each provided term. (a) Stark effect is the splitting of spectral lines under the influence of an electric field, not magnetic. (b) Zeeman effect refers to the splitting of spectral lines due to the presence of a magnetic field. (c) Photoelectric effect is the emission of electrons from a material when light shines upon it. (d) Screening effect describes the reduction in effective nuclear charge due to inner-shell electrons.

Identifying the Correct Term

With the knowledge of what each term represents, identify that the Zeeman effect is the correct answer as it specifically refers to the splitting of spectral lines caused by the application of a magnetic field.

Key concepts

Spectral Lines Splitting

In physics, when we speak of spectral lines splitting, we refer to the phenomenon where a single spectral line is divided into multiple components. This can occur under various circumstances, but it is notably observed when atoms or molecules are subjected to an external magnetic or electric field. One of the most long-studied examples includes the Zeeman effect, where this phenomenon is attributed to the influence of a magnetic field.

The splitting occurs because the energy levels of electrons in atoms are quantized, and these levels can shift differently when exposed to a field. This leads to the appearance of adjacent lines where there used to be one. Students tackling this concept should visualize the process as akin to a single note being split into a chord when a magnetic field is 'strummed' across the atomic 'strings'.

Magnetic Field

A magnetic field is an essential concept not just in physics, but also in everyday life, as it explains how magnets work and why certain materials are affected by them while others are not. The magnetic field is a vector field, represented by lines of force. An easy analogy is to think of the field as wind that can apply a force but is only felt by certain objects, like leaves - or, in our atomic example, the 'wind' felt by the spectral lines.

The Earth itself is a magnet with its own magnetic field, which is why compasses point north. Magnetic fields from permanent magnets or electromagnets interact with charged particles or objects, which can include anything from metal filings displaying a magnetic field shape to electrons in atoms experiencing energy level shifts leading to the spectral line splitting observed in the Zeeman effect.

Stark Effect

Comparable to the Zeeman effect, the Stark effect is another form of spectral line splitting. However, rather than being caused by a magnetic field, the Stark effect is a result of applying an external electric field. This effect is significant not only for its implications in atomic and quantum physics but also for its role in confirming the quantum theory and the distribution of electron orbits.

Students can think of the Stark effect like placing a charged object next to neutral ones; that charged object would invariably attract or repel parts of those neutral objects, much like an electric field influences the energy levels in atoms. The Stark effect is a wonderful example which illustrates the discrete nature of quantum systems and underscores the difference between electric and magnetic effects on spectral lines.

Photoelectric Effect

Moving away from the topic of spectral lines, the photoelectric effect is another significant phenomenon in physics. Discovered by Heinrich Hertz and later explained by Albert Einstein, the photoelectric effect involves the emission of electrons from a material when it absorbs light or more generally, electromagnetic radiation. Students might relate well when imagining how sunlight triggers solar panels; much in the same way, light can induce electrons to leave the surface of a metal.

The concept reveals a lot about the nature of light and its particle-like behavior, contributing to the understanding of quantum mechanics. It also has practical applications, with its principles applied in devices like photodiodes and solar cells.

Screening Effect

Lastly, the screening effect, also known as the shield effect, is a concept that describes how electrons in an atom affect each other's experiences of the nucleus's positive charge. Inner-shell electrons, which are closer to the nucleus, shield outer-shell electrons from the full electrostatic pull of the nucleus.

It's similar to being in a crowded room and trying to hear someone call your name; if you're further away and surrounded by people (other electrons), the call (nuclear charge) is harder to hear (less effective). This effect plays a significant role in numerous phenomena, including the periodic trends of atomic and ionic sizes, as well as ionization energy across the periodic table.