7 Factors Affecting the Frequency of a Vibrating String

Question 1

what is a stationary wave

Answer 1

a wave that stores but does not transfer energy

Question 2

what piece of apparatus can be used to generate a wave on a piece of string

Answer 2

a vibration generator

Question 2

how do stationary waves form on a piece of string

Answer 2

two waves with the same wavelength travelling in opposite directions interfere with each other. when this occurs they undergo superposition and a stationary wave is formed

Question 3

what is a node

Answer 3

a point of zero displacement on a standing wave. occurs when two waves are in anti phase and so destructively interfere such that they completely cancel each other out

Question 4

what is an antinode

Answer 4

a point of maximum displacement where two waves are in phase and so constructively interfere to form a maximum

Question 5

what is the arrangements of nodes and antinodes when a string is vibrating at its fundamental frequency

Answer 5

one central antinode with one node at each end

Question 6

what piece of apparatus can be used to alter the length of string oscillating

Answer 6

a bridge (triangular prism shaped object)

Question 7

why should the signal operator be operated for several minutes before use

Answer 7

it needs time for the frequency to stabilise

Question 8

in this experiment the string is tied to a clamp stand. to carry out the experiment safely what must be added to the clamp stand

Answer 8

a counterweight or a clamp to produce a counteracting moment to prevent the stand from falling over

Question 9

how does the string mass per unit length affect the frequency of the first harmonic

Answer 9

as mass per unit length increases the frequency decreases

Question 9

how does the tension in the string effect the frequency of the first harmonic

Answer 9

as the tension increase the frequency increases

Question 10

how does the length of the string effect the frequency of the first harmonic

Answer 10

there is an inverse relationship between the string length and the frequency of the first harmonic.

Question 11

how can the tension in the string be varied

Answer 11

by attaching a mass hanger to the end of it. more mass means more tension

Question 12

how can you measure the mass per unit length of a piece of string

Answer 12

measure its mass using a balance and divide it by the strings length

Question 13

what’s the advantage of using a long piece of string when measuring mass per unit length

Answer 13

the longer the piece of string the lower the percentage uncertainty in the measurement

Question 14

assuming all other factors remain constant, what is the effect of changing the frequency to double that of the first harmonic

Answer 14

the string will resonate in its second harmonic

Question 14

when vibrating in its fundamental mode, what is the wavelength relative to the length of the string

Answer 14

wave length is double the length on string

Question 15

what are the uncertainties in this experiment

Answer 15

the speed of vibrations will result in a blur at the nodes making the wavelength difficult to measure accurately. the calibration of the signal generator

Question 15

when plotting a graph of 1/f against L for a waves fundamental frequency, how can the wave speed be determined

Answer 15

the gradient will be 1/fL and wave speed is 2fL so frequency is so is given by 2/gradient