RP 1 stationary waves on a string

Question 1

what is the overall aim of this practical?

Answer 1

• to measure how the frequency of the first harmonic is affected by changing:
• length, tension or mass per unit length

Question 2

what is the general method for carrying out this practical?

Answer 2

• set up apparatus
• adjust length of string so it is 1m, measured using metre ruler
• increase frequency until string oscillator at first harmonic, read value
• repeat prodecudre with different lengths
• repeat frequency readings at least two times and take an average
• measure tension using t=mg

Question 3

what do we plot in this experiment?

Answer 3

• mean value of frequency against 1/L

Question 4

what is the gradient in this experiment?

Answer 4

• gradient is fL
• wave speed is 2x gradient

Question 5

how can we verify the signal generators readings?

Answer 5

• use an oscilloscope

Question 6

how can we stabilise the signal generator?

Answer 6

• leave it on for 20 mins beforehand

Question 7

how can we reduce systematic errors in measurements?

Answer 7

• decerease string length by same increment each time

Question 8

how can we overcome the biggest problem when determining when the first harmonic has been reached?

Answer 8

• adjust frequency whilst looking closely at a node, as looking at amplitude will be less reliable as wave is very fast

Question 9

what are some safety precautions?

Answer 9

• stand away from masses
• use goggles if metal wire
• use rubber string instead of metal wire