a) Describe the emission spectrum of a hydrogen discharge tube
b) Explain why different color lines appeared in different position in the spectrum. Use a suitable atomic model to help construct your answer.
c) Explain how do you decide if the lines observed are of the first order interference or from the higher order of interference.
a) The emission spectrum of a hydrogen discharge tube is composed of a series of discrete lines or bands of light at specific wavelengths. These lines or bands correspond to the emission of photons as electrons transition between different energy levels within the hydrogen atoms.
b) The different color lines in the spectrum are a result of the energy differences between the allowed energy levels in the hydrogen atom. To understand this, we can use the Bohr model of the atom. According to this model, electrons orbit the nucleus in specific energy levels or shells. When an electron absorbs energy, it moves to a higher energy level. Conversely, when an electron releases energy, it moves to a lower energy level.
In the case of hydrogen, when the electrons move from higher energy levels to lower energy levels, they release energy in the form of light. Each energy level corresponds to a specific wavelength of light. The energy difference between energy levels determines the color of the emitted light.
The Balmer series is a specific set of hydrogen emission lines in the visible spectrum. It consists of lines corresponding to electron transitions from higher energy levels to the second energy level (n=2). These transitions produce visible light, with each line representing a different color. The Balmer series includes spectral lines such as red at 656.3 nm, blue-green at 486.1 nm, and violet at 434.1 nm.
c) To determine if the observed lines are of the first order interference or from higher orders of interference, we need to consider the properties of interference patterns. Interference occurs when two or more waves overlap, creating patterns of constructive and destructive interference.
In interference patterns, the central bright maximum is known as the first order maximum. The second bright maximum on either side is the second order maximum, and so on. These orders of interference are marked by the positions of bright and dark bands. The first order maximum is the brightest and most prominent.
To decide if the observed lines are from the first order interference or from higher orders, we need to examine the brightness and sharpness of the lines. If the lines are very bright, sharp, and distinct, they are likely from the first order interference. On the other hand, if the lines are dimmer, blurred, or have neighboring lines of equal brightness, they may be from higher orders of interference.
Examining the positions of the lines can also provide a clue. If the lines are spaced relatively evenly and follow a predictable pattern, they are likely from higher orders of interference. However, if the lines are closely packed and centered around a prominent line, they are likely from the first order interference.