The Major Advantages of the 21-Cm Radio Emission from Hydrogen

question 132

Multiple Choice

The major advantages of the 21-cm radio emission from hydrogen gas for investigating the spiral structure of the Milky Way Galaxy are that

• A) it is relatively easily absorbed by hydrogen gas in the Milky Way, so measurements are not confused by emission of this radiation from other galaxies beyond the Milky Way. It originates only from cold hydrogen gas and can be used to map this important component.
• B) radio waves easily penetrate the Milky Way dust and gas, and they are a very narrow-wavelength line emission; thus its Doppler shift can be used to measure gas motions.
• C) Doppler shift of this narrow-wavelength line emission is caused by the temperature of the hot hydrogen gas and therefore can be used to measure the distribution and temperature of this important component of the Milky Way.
• D) this emission can easily penetrate the Milky Way gas and dust and comes only from hot gas, hence its ability to be used to map the distribution of hot hydrogen gas.

Comprehend the role of fixed and variable costs in budgeting and financial performance evaluation.

Understand the process and importance of comparing actual costs and revenues to budgeted amounts.

Grasp the significance of activity levels in the management of costs and the preparation of flexible budgets.

Interpret the implications of variances on material cost and efficiency.

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Definitions:

Listening Style

The particular way or method a person prefers to receive and process auditory information from others during communication.

Listening Effectively

The skill of paying close attention to and comprehending the messages being communicated by others.

Subject Matter

Subject matter pertains to the topic or content that is being discussed, studied, or represented.

Ineffectively

Without producing the desired outcome or failing to achieve the intended effect.