Light behaving as a wave

Question 1

Electromagnetic spectrum

Answer 1

electromagnetic spectrum the range of all possible electromagnetic waves ordered by frequency or wavelength

Question 2

Electromagnetic wave

Answer 2

Electromagnetic wave a transverse wave comprised of changing electric fields and perpendicular changing magnetic fields produced by the acceleration of charged particles. Unlike a mechanical wave, it does not require a medium

Question 3

Fringe spacing

Answer 3

fringe spacing the distance between adjacent bright or dark bands in a double slit interference pattern

Question 4

Properties of light as a electromagnetic wave

Answer 4

-Light can be modelled as an electromagnetic wave comprised of changing perpendicular electric and magnetic fields. - It is produced by the acceleration of charged particles. -The speed of electromagnetic waves in a vacuum is a constant.

Question 5

How are light particles effected regarding motion?

Answer 5

A stationary charged particle has a constant electric field around it. When the particle is accelerating, this electric field changes. A changing electric field produces a perpendicular changing magnetic field, and the changing magnetic field likewise produces a changing electric field (electromagnetic wave/radiation). This means an accelerating particle will emit electromagnetic waves

Question 6

What occurs to oscillating charged particles?

Answer 6

If the charged particle is oscillating, the frequency of the electromagnetic wave will be equal to the frequency of the oscillation.

Question 7

Do electromagnetic waves require a medium?

Answer 7

No. Only mechanical waves require a medium.

Question 8

Electromagnetic wave equation

Answer 8

Electromagnetic waves can be described by the wave equation with c substituted in as the wave’s velocity: c = f λ.

Question 9

Electromagentic spectrum diagram

Answer 9

Question 10

Propertities of Radio waves

Answer 10

• Travel long distances uninterrupted due to their long wavelength
• Diffract around obstacles like buildings and mountains and can reflect off the ionosphere to help travel long distances
• Mostly used in radio and television communications where they are emitted by radio towers and picked up by antennae on devices such as car radios

Question 11

Propertities of microwaves

Answer 11

• Used to cook food in microwave ovens by matching the resonant frequency of water molecules in food causing them to vibrate
• Also used for mobile phone signals, Wi-Fi and radar systems
• Cosmic microwave background (CMB) radiation is electromagnetic radiation which was created in the early stages of the universe and continues to reach Earth, and provides strong evidence for the Big Bang Theory

Question 12

Propertities of infared

Answer 12

• All objects emit electromagnetic radiation due to the thermal vibration of charged particles. At temperatures for which life exists most of this radiation is infrared. For this reason thermal vision goggles use infrared and convert it to visible light to ‘see’ temperature.
• When infrared radiation hits an object, it causes the particles in that object to vibrate so the object heats up. Radiator heaters and heating lamps use this principle.
• It is also used in some forms of signal transmission such as TV remote controls.

Question 13

Propertities of visible light

Answer 13

• It allows humans (and many species) to see.
• When we see an object as coloured, the object is reflecting the wavelengths of the colour it appears to be and absorbing the complementary (all other) wavelengths.
• Red is at the low frequency/long wavelength end of the visible spectrum and violet is at the high frequency/short wavelength end

Question 14

Properties of ultralight

Answer 14

• Used in sterilisation processes and to cure (harden) different materials due to its high energy
• Used in black lights (UV light bulbs) for forensic analysis as it causes other substances, including bodily fluids, to fluoresce (emit visible light)
• Produced along with visible light and infrared by the Sun

Question 15

Propertities of X-Rays

Answer 15

• High energy and highly penetrating
• Useful for imaging bone structures as they pass easily through soft tissue
• Can damage the DNA in cells or even kill cells in significant doses
• Produced by cosmic objects and used by astronomers to study those objects

Question 16

Properties of Gamma Rays

Answer 16

• Higher energy, more penetrating, and more damaging than x-rays
• Produced by nuclear reactions
• Used in medicine to target and kill tumour cells but care must be taken to minimise damage to other cells
• Produced by cosmic objects and used by astronomers to study those objects

Question 17

Youngs double split experiment

Answer 17

In 1801, a physicist called Thomas Young performed an experiment in which he shone light through two slits onto a screen and observed alternating bright and dark regions.

Which challanged the particle nature of light as his experemnt demonstrated the wave properties of diffraction and interference.

Question 18

In Youngs experiement how are the bright bands are caused?

Answer 18

The bright bands are caused by constructive interferance (where two waves meet together and increase wave amplitude)

Question 19

In Youngs experiement how are the dark bands are caused?

Answer 19

Dark bands are caused by deconstructive interferance where the maximun of two waves meet and cancel eachother out.

Question 20

Diagram of the results of Youngs experiment

Answer 20