Waves and Light Definitions

Question 1

What is Normal?

Answer 1

Force acting at right angles to a surface.

Question 2

What is Pressure?

Answer 2

Force perpendicular to surface per unit area.

Question 3

What is Amplitude?

Answer 3

Maximum displacement of a wave from equilibrium.

Question 4

What is Diffraction?

Answer 4

Bending of waves around gaps/edges.

Question 5

What is Frequency?

Answer 5

Number of waves per second (1/period).

Question 6

What is Longitudinal wave?

Answer 6

Oscillations parallel to wave direction.

Question 7

What is Reflection?

Answer 7

Bouncing back of waves at boundaries.

Question 8

What is Refraction?

Answer 8

Change in wave speed/direction crossing media.

Question 9

What is Speed of a wave?

Answer 9

Distance travelled by wave point per time.

Question 10

What is Transverse wave?

Answer 10

Oscillations perpendicular to wave direction.

Question 11

What is Vibration?

Answer 11

Oscillation about equilibrium.

Question 12

What is Water wave?

Answer 12

Waves on water surface.

Question 13

What is Wave?

Answer 13

Energy transfer via oscillations without matter transfer.

Question 14

What is Wavefront?

Answer 14

Surface of points in same wave phase.

Question 15

What is Wavelength?

Answer 15

Distance between equivalent points on adjacent waves.

Question 16

What is Angle of incidence?

Answer 16

Angle between incident ray and normal.

Question 17

What is Angle of reflection?

Answer 17

Angle between reflected ray and normal.

Question 18

What is Optical image?

Answer 18

Apparent reproduction of an object by lenses or mirrors.

Question 19

What is Plane mirror?

Answer 19

Flat reflective surface forming virtual, upright images of same size.

Question 20

What is Critical angle?

Answer 20

Incidence angle beyond which total internal reflection occurs.

Question 21

What is Optical fibre?

Answer 21

Flexible glass core transmitting light by total internal reflection.

Question 22

What is Refractive index?

Answer 22

Ratio of light speed in vacuum to that in a medium.

Question 23

What is Total internal reflection?

Answer 23

Complete reflection at boundary when angle > critical.

Question 24

What is Diminished?

Answer 24

Made smaller.

Question 25

What is Enlarged?

Answer 25

Made larger.

Question 26

What is Focal length?

Answer 26

Distance from lens centre to principal focus.

Question 27

What is Focus?

Answer 27

Point where rays from object converge.

Question 28

What is Long-sightedness (Hyperopia)?

Answer 28

Blurry near objects; corrected with convex lenses.

Question 29

What is Magnifying glass?

Answer 29

Convex lens enlarging image.

Question 30

What is Principal focus?

Answer 30

Point where parallel rays converge.

Question 31

What is Real image?

Answer 31

Projectable image formed by converging rays.

Question 32

What is Short-sightedness (Myopia)?

Answer 32

Blurry distant objects; corrected with concave lenses.

Question 33

What is Virtual image?

Answer 33

Non-projectable image formed by apparent divergences.

Question 34

What is Dispersion?

Answer 34

Splitting white light into spectrum.

Question 35

What is Glass prism?

Answer 35

Transparent element refracting light.

Question 36

What is Monochromatic light?

Answer 36

Single frequency light.

Question 37

What is Spectrum?

Answer 37

Range of electromagnetic wavelengths/frequencies.

Question 38

What is Electromagnetic spectrum?

Answer 38

Transverse waves covering a range of frequencies/wavelengths; γ-rays highest frequency, radio lowest. Speed in vacuum ≈3.0×10^8 m/s.

Question 39

What is Infrared?

Answer 39

Cooking, thermal imaging, can cause burns.

Question 40

What is Microwaves?

Answer 40

Satellite communications, cooking, internal heating of cells.

Question 41

What is Radio waves?

Answer 41

TV/radio signals; produced or induce circuit oscillations.

Question 42

What is Vacuum?

Answer 42

Space devoid of matter.

Question 43

What is X-rays?

Answer 43

Medical imaging, security; can cause damage/mutations.

Question 44

What is Audible frequencies?

Answer 44

Periodic vibrations 20 Hz–20 000 Hz.

Question 45

What is Compressions?

Answer 45

High-pressure regions in longitudinal waves.

Question 46

What is Echo?

Answer 46

Reflected sound wave.

Question 47

What is Loudness?

Answer 47

Amplitude of oscillations.

Question 48

What is Pitch?

Answer 48

Frequency of oscillations.

Question 49

What is Rarefactions?

Answer 49

Low-pressure regions.

Question 50

What is Sound waves?

Answer 50

Longitudinal vibrations requiring a medium.

Question 51

What is Speed of sound?

Answer 51

Distance per time travelled by sound wave.

Question 52

What are Ultrasound waves?

Answer 52

A sound wave that has a frequency >20 kHz, and is inaudible to a healthy human ear.