Stationary Waves

Question 1

What is a standing wave?

Answer 1

• When two waves of same wavelength, travelling in opposite direction, superpose.

Question 2

How do you create a standing wave?

Answer 2

• Waves from signal generator pass to the vibration generator to the fixed masses (end) along the string.
• Wave then reflects back along the string and superposes with the wave in the opposite direction.
  -This produces a stable wave pattern with both nodes and antinodes.

Question 3

What is a node?

Answer 3

• Area along the wave where there is always 0 displacement.

Question 4

What is an antinode?

Answer 4

• Area along the wave where it fluctuates from maximum positive to maximum negative displacement.

Question 5

Difference one btwn stationary and progressive waves:

Answer 5

Stationary:
- All points btwn two nodes oscillate in phase (same point in their cycle) with each other.
- Points btwn the next two nodes in anti phase to first set.
- Amplitude depends on position.

Progressive:
- Each point on the wave oscillates with the same amplitude.
- Phase of the point depends on the position.
- Points further from the source being delayed.

Question 6

Difference two btwn stationary and progressive waves:

Answer 6

Stationary:
- Energy stored within the wave (said to be stationary).

Progressive:
-Energy moved from one end of the wave to the other.

Question 7

Difference 3 btwn stationary and progressive waves:

Answer 7

Stationary:
- Wavelength is 2x distance btwn two adjacent nodes/antinodes.

Progressive:
- Wavelength is difference btwn two adjacent points which are in phase, e.g, peak to peak.

Question 8

What is the first frequency a standing wave occurs at called?

Answer 8

Fundamental frequency

Question 9

What is a harmonic?

Answer 9

Additional standing wave patterns at exact multiples of the fundamental frequency.