Waves

Question 1

E =kA^2

Answer 1

E₁/A₁^2 = E₂/A₂^2

E = Energy (J)
A = Amplitude (m)

Question 2

Travelling wave equation

y = Asin2π(ft - x/λ)

for a wave travelling left to right

y = Asin2π(ft + x/λ)

for a wave travelling right to left

Answer 2

y = displacement (m)
x = distance from the origin of the particle (m)
f = frequency (Hz)
t = time (s)
λ = wavelength (m)

Question 3

Phase Difference

ø = 2π(x/λ)

Answer 3

ø = Phase angle (rad)
π = pi
x = distance between points on a wave (m)
λ = wavelength (m)

Question 4

Stationary Waves

Answer 4

are formed by the interference of two waves that are REFLECTED the waves have the same frequency and amplitude, travelling in opposite directions. A stationary wave can be described in terms of nodes and antinodes.

The incident and reflected waves interfere.

Question 5

how do you calculate λ from this travelling wave equation

y = 9.50x10^-4sin(922t-4.50x)

Answer 5

2π has been factored into both the frequency and the wavelength thus

4.50 = 2π/λ
so
λ = 2π/4.50

Question 6

how do you calculate λ from this travelling wave equation

y = 0.250sin2π (118t - 0.357x)

Answer 6

2π has NOT been factored in this equation.

thus

0.357 = 1/λ
so
λ= 1/0.357

Question 7

if the frequency of a stationary wave is increased what will happen to the sound?

Answer 7

the sound will get quieter until the frequency has doubled.

Question 8

if the frequency is doubled then what happens to the wavelength

Answer 8

the wavelength is then halved.

as frequency and wavelength are proportional to each other.