Electromagnetic Spectrum

Question 1

Regarding electromagnetic radiation (true or false):

The speed of propagation is proportional to the frequency

Answer 1

False. The speed of propagation is constant for the whole of the electromagnetic spectrum, and is equal to the speed of light (c).

Question 2

Regarding electromagnetic radiation (true or false):

It consists of a single oscillating electrical field at right angles to the direction of propagation

Answer 2

False. EM radiation consists of two oscillating electrical and magnetic fields, perpendicular to both each other and the direction of propagation.

Question 3

Regarding electromagnetic radiation (true or false):

Some wavelengths of infrared radiation are visible to the human eye

Answer 3

False. By definition, only the visible part of the EM spectrum can be seen by the human eye.

Question 4

Regarding electromagnetic radiation (true or false):

The energy carried is proportional to the frequency

Answer 4

True. The amount of energy carried is the product of the frequency and Planck’s constant.

Question 5

Regarding electromagnetic radiation (true or false):

Gamma rays carry the most energy in the electromagnetic spectrum

Answer 5

True. Following from the above answer, since gamma waves have the highest frequency they must carry the most energy.

Question 6

Regarding the waveform of electromagnetic radiation (true or false):

It is an example of a transverse sine wave

Answer 6

True. The oscillations occur perpendicular to the direction of propagation.

Question 7

Regarding the waveform of electromagnetic radiation (true or false):

Radio waves are of a longer wavelength than x-rays

Answer 7

True

Question 8

Regarding the waveform of electromagnetic radiation (true or false):

Radio waves demonstrate more wave-like properties, e.g. interference, when compared to gamma waves

Answer 8

C. True. For EM radiation, the longer the wavelength, the more the wave-like properties predominate.

Question 9

Regarding the waveform of electromagnetic radiation (true or false):

Wavelength and frequency are directly proportional

Answer 9

False. Wavelength and frequency are inversely proportional.

Question 10

Regarding the waveform of electromagnetic radiation (true or false):

Ultraviolet has a higher frequency than infrared radiation

Answer 10

True

Question 11

Regarding quantum effects (true or false):

A shift of an electron away from the nucleus requires the uptake of energy

Answer 11

True. A move of an electron away from its ground state requires energy.

Question 12

Regarding quantum effects (true or false):

The energy difference between two orbital levels is constant for all atomic elements

Answer 12

False. Each atomic element has orbital levels, distinguished by precise and identifiably different energies. This is one of the principal features of quantum theory and mechanics.

Question 13

Regarding quantum effects (true or false):

Sodium produces spectral emission lines within the visible spectrum

Answer 13

True. If this were not the case, sodium street lights, for example, would not be visible.

Question 14

Regarding quantum effects (true or false):

Spectral absorption lines are characteristic for each compound

Answer 14

True. This property is used to identify different compounds in absorption spectroscopy.

Question 15

Regarding quantum effects (true or false):

Oxygen absorbs infrared radiation