Waves ( 1 )

Question 1

What are waves that pass through a substance?

Answer 1

• Waves that pass through a substance are vibrations which pass through that substances

Question 2

What are mechanical waves?

Answer 2

• Waves that pass through a substance

Question 3

What are electromagnetic waves?

Answer 3

• Oscillating electric and magnetic fields that progress through space without the need fro a substance.

Question 4

How do electromagnetic waves progress through space?

Answer 4

• Without a substance
• Vibrating electric field generates a vibrating magnetic fields which generates a vibrating electric field further away and so on.

Question 5

What are some examples of electromagnetic waves?

Answer 5

• X Rays
• Gamma Radiation
• Infrared Radiation
• Microwaves
• Light
• Ultraviolet radiation

Question 6

What are longitudinal waves?

Answer 6

Waves in which the direction of vibration of the particles is parallel to the direction in which the wave travels

Question 7

What are transverse waves?

Answer 7

Waves in which the direction of vibration is perpendicular to the direction in which the wave travels

Question 8

What are some examples of seismic waves?

Answer 8

• Electromagnetic waves

* Waves on a string

Question 9

What does it mean for a wave to be plane polarised?

Answer 9

Vibrations stay in one plane only

Question 10

What does it mean for waves to be unpolarised?

Answer 10

Vibrations change from one plane to another

Question 11

What waves can be polarised?

Answer 11

Transverse waves

Question 12

What waves cannot be polarised?

Answer 12

Longitudinal

Question 13

What do polarising filters do?

Answer 13

Transmit vibrations in one direction only

Question 14

What are ordinary light waves?

Answer 14

A mixture of different directions of vibrations

Question 15

What type of wave are electromagnetic waves?

Answer 15

Transverse

Question 16

What happens if unpolarised light passes through a Polaroid filter?

Answer 16

• Light will be transmitted on the other side
• Transmitted light is polarised as the filter only allows through light which vibrates in a certain direction, according to the alignment of its molecules

Question 17

What happens if unpolarised light is passed through two filters?

Answer 17

• Transmitted light intensity changes if one Polaroid is turned relative to the other one

Question 18

What does it mean by filters being crossed?

Answer 18

• Filters are said to be crossed when the transmitted intensity is a minimum.
• At this position, the polarised light from the first filter cannot pass through the second filter, as the alignment of molecules in the second filter is at 90 degrees to the alignment in the first filters

Question 19

What is the plane of polarisation of an electromagnetic wave?

Answer 19

Plane in which the electric field oscillates

Question 20

How do polaroid sunglasses work?

Answer 20

• Reduce the glare of light reflected by water or glass.

* Reflected light is polarised and the intensity is reduced when it passes through the Polaroid sunglasses

Question 21

How can light be partially polarised?

Answer 21

• Light becomes partially polarised when reflected from some surfaces
• Some of it vibrates in the same direction