wave behaviour - standing waves

Question 1

When do standing waves occur?

Answer 1

superposition of two identical waves travelling in opposite directions

Question 2

When are stable interference patterns seen?

Answer 2

When waves are coherent

Question 3

What is an antinode?

Answer 3

Where waves combine to make a larger oscillation

open points on diagram

Question 4

What is a node?

Answer 4

Where waves add to zero

crossing points on diagram

Question 5

What is the spacing of nodes and antinodes?

Answer 5

half a wavelength

Question 6

What is the fundamental?

Answer 6

The lowest frequency which can form a standing wave

Question 7

What sounds can be heard other than the fundamental?

Answer 7

Harmonics - higher frequencies which from shorter wavelength standing waves in the same space

Question 8

What happens at the ends of a space with two fixed ends?

Answer 8

A node at either end

Question 9

What is the formula for frequencies with two fixed ends?

Answer 9

fn = nf1

Question 10

What can the fundamental be represented by?

Answer 10

f1

Question 11

What is the formula for length of space with two fixed ends?

Answer 11

L = 1/2 n wavelengths

Question 12

Give a musical example of a space with two fixed ends

Answer 12

guitar string

Question 13

What happens at the ends of a space with two open ends?

Answer 13

An antinode at either end

Question 14

What is the formula for frequencies with two fixed ends?

Answer 14

fn = nf1

Question 15

What is the formula for length of space with two fixed ends?

Answer 15

L = 1/2 n wavelengths

Question 16

Give a musical example of a space with two open ends

Answer 16

organ pipes or flute

Question 17

What happens at the ends of a space with one open end and one fixed end?

Answer 17

A node at the fixed end and an antinode at the open end

Question 18

What is the formula for frequencies with two fixed ends?

Answer 18

Fn = (2n-1)xF1

Question 19

What is the formula for length of space with two fixed ends?

Answer 19

L = (2n-1)/4 wavelengths

Question 20

Give a musical example of a space with one fixed and one open end

Answer 20

clarinet

Question 21

What happens to a pulse at an open end?

Answer 21

Pulse is not inverted

Question 22

What happens to a pulse at a fixed end?

Answer 22

The pulse is inverted

Question 23

How is a standing wave usually formed?

Answer 23

A wave is reflected back on itself

Question 24

Why is it better to measure a standing wave near the reflector?

Answer 24

Energy, and so amplitude, is lost with distance so this is where amplitudes are most similar and the expected interference patterns are seen