Topic 5- Waves Flashcards

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1
Q

What is displacement?

A

The position of a particular point on a wave, at a particular instant in time, measured from the mean.

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2
Q

What is amplitude?

A

The magnitude of the maximum displacement, reached by an ocscillation in the wave.

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3
Q

What is frequency?

A

The number of complete wave cycles per second.

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4
Q

What is wavelength?

A

The distance from any point on a wave to an identical point on the next cycle of wave.

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5
Q

Define period?

A

The time required to complete one cycle of a wave.

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6
Q

What is a phase?

A

The stage a given point on a wave is through a complete cycle. Measured in angle units.

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7
Q

Define wave speed?

A

The rate of movement of the wave, measured in m/s

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8
Q

Equation that links, wave speed, frequency, and wavelength.

A

Wave speed=frequency x wavelength

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9
Q

Equation that links, time period and frequency?

A

Frequency = 1/time period

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10
Q

Are sound waves longitudinal or transverse?

A

Sound waves are longitudinal, so oscillations occur parallel to the direction of movement.

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11
Q

What is compression?

A

Area in longitudinal waves where the particle oscillations put them closer to each other than their equilibrium state.

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12
Q

What is a wavefront?

A

The difference between two peaks (highest point on a wave) or two troughs (lowest point on a wave). Drawn as lines.

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13
Q

What is constructive interference?

A

Where two waves arrive in step reinforcing one another (increasing the amplitude)

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14
Q

What is destructive interference?

A

Where two waves arrive out of phase (exactly 180°) cancelling one another out.

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15
Q

What is a stationary wave?

A

A stationary wave consists of oscillations in a fixed space, with reigons of significant oscillation, and regions with 0 oscillations.

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16
Q

When are waves coherent?

A

Waves are coherent if they have the same frequency and a constant phase relationship.

17
Q

What are nodes?

A

Reigons on a stationary wave where the amplitude of oscillation is 0.

18
Q

What is superposition?

A

The adding together of wave displacements that occurs when waves from 2 or more separate sources overlap. They add together.

19
Q

What’s coherence?

A

Same frequency and wavelength and a fixed phase difference.

20
Q

What kind of image is created if the object is more than one focal length away from the lens?

A

Real

21
Q

What kind of image is created if the object is less than one focal length away from the lens?

A

Virtual

22
Q

What is the critical angle?

A

The angle of incidence when the angle of refraction is 90 degrees, and all light passes along the boundary between the mediums.

23
Q

What happens when the angle of incidence is above the critical angle?

A

All light is reflected.

24
Q

What is total internal reflection?

A

Total internal reflection is where all the light is reflected inside a material, it occurs when the angles of incidence is greater than the critical angle.

25
Q

What is the focal point of a converging lens?

A

What is the focal point of a converging lens?

26
Q

What is the focal length of a lens?

A

The distance from the centre of a lens to the focal point.

27
Q

What is the equation used to calculate the power of a lens?

A

Power=1/Focal length

28
Q

What is a real image?

A

Where the light from an object comes together to form an image on a ‘screen’ - like the image formed on the eye’s retina. They are the consequence of light meeting at a focal point.

29
Q

What is a virtual image?

A

Virtual images are the consequence of rays of light appearing to meet at a point. They cannot be projected.

30
Q

Equation for magnification

A

magnification= image height / object height

31
Q

Describe a transverse wave

A

The oscillations are perpendicular to the direction of energy transfer, consists of peaks and troughs.

32
Q

What’s a standing wave?

A

A wave that stores energy rather than transferring it from one place to another.

33
Q

Evidence for the wave nature of light?

A

Thomas Youngs double slit experiment. Light expanded in wave fronts. Light propagates through space as a wave

Interference and diffraction

-Electron did france de Broglie, big bulb thing
-Crystaline structure, graphite

34
Q

If light was a wave, what would happen w photo electric effect?

A

No threshold frequency, dependant of exposure time.
KE of emitted electrons should increase with intensity.

None of this was observed.