WAVES
Wavelength & Amplitude
The distance
between X & Y is 4m. What is the wavelength? 4m
The distance
between X & Y is 3m. Calculate the wavelength? 2m
The distance
between X and Y is 18m. Calculate the wavelength. 2m
The distance
between X and Y is 25cm. Calculate the wavelength 4.17cm
Frequency
A.
The
string on a violin completes 4500 vibrations in 4 seconds. Calculate the
frequency. 1125 Hz
B.
The
cone on a loudspeaker completes 500 vibrations in 0.53 seconds. Calculate the
frequency. 943.4 Hz
C.
Mains
ac completes 1 complete oscillation in 0.2 s. Calculate the frequency. 5Hz
D.
A
fishing boat is tossed up and down on the stormy sea. Captain Haddock counts 12
complete wave peaks in 1 minute (seconds). Calculate the frequency of the
waves. 12 ÷ 60 = 0.02Hz
E.
The
earth rotates once every 24hrs. Calculate the frequency.
1
÷ 86400 = 0.000012 Hz
Wave
Equation
1.
A
mighty ocean wave has a frequency
of 3Hz. The wave has
wavelength of 8m. Calculate
the velocity of the wave. 24m/s
2.
A
ripe plum falls off a tree into still pond. It produces ripples which have a wavelength of 5 cm (0.05m). The ripples have
a frequency of 6Hz. Calculate the velocity of the waves? 0.3 m/s
3.
An
irritating child twangs a ruler on the edge of the desk. It produces a note of
170Hz. The speed of sound is 340m/s. Calculate the wavelength of the sound. 2m
4.
A
slinky vibrates at a frequency of 20Hz. The wave it produces in the slinky
travels at 10m/s. Calculate the wavelength of the vibrations. 0.5 m/s
5.
A
vandal hits a railway line with a hammer. The sound travels through the steel
line at 5000m/s. It has a wavelength of 10cm (0.1m). Calculate the frequency of
the sound. 50 000 Hz
6.
A
seagull lands on a telephone wire and sets it bouncing. The wave in the wire
travels at 5 m/s. the wavelength is 60cm (how many metres?). Calculate the
frequency of the wave. 8.33 Hz
Questions about light and
other electromagnetic waves.
Now try
these.
a. WCKA broadcasts to the good folk of Jacksonville,
AL on 810 Mhz. Calculate the wavelength. (remember
speed of light) 0.37 m
b.
The
lowest frequency of light our eyes can detect is about 390 nm. Calculate the
frequency of this blue light. 7.69 x 1014 Hz
c.
The
Marconi wireless set on the Titanic broadcast at 500kHz. Calculate the
wavelength of those radio waves. 600m
d.
Our
warm bodies emit i-r of wavelength 9.36 x 10-4 m. Calculate the
frequency.
3.21 x 1011 Hz
e.
Apollo
13 alerted Houston of its problem using radio waves of a frequency 2272.5MHz.
Calculate the wavelength of the radio waves.
0.13 m
f.
A
microwave oven produces electromagnetic waves with a wavelength of 122 mm (÷
1000). Calculate the frequency of these waves. 2.46 x109
Hz
Questions that require you to
think.
Now try these
i.
A
sound wave has a wavelength of 1.8m. The speed of sound in air is 340m/s. show its
frequency is approximately 190 Hz. The sound then enters water where its speed
is 1500 m/s. What is the frequency of the sound in water. 188.9 Hz Calculate its new wavelength. 1.8m
ii.
Blue
light has a wavelength of 475 nm. The speed of light in water is 225 000 km/s
(x 1000 for m/s). Show the frequency of this light is approximately 5 x1014
Hz.
.
The light enters diamond where the speed of light is 1.1 x 108 m/s. What
is the frequency of light in diamond? 4.74 x 1014
Hz Calculate the wavelength of the light in diamond. 2.32 x 10-7 Hz
iii.
A
sound wave passes through a steel rail. It has a frequency of 4 kHz and a
wavelength of 1.25 m. Calculate the velocity of sound in steel. 5000 m/s The sound passes from the steel to air where
its velocity is 342 m/s. What is the frequency of sound in air? 4 kHz Calculate the wavelength of this note. 0.0855 m/s
iv.
Hospital
sonographers emit sound of frequency 18MHz.In soft tissue the sound has a
velocity of 1500 m/s. Show that the wavelength is approximately 8 x 10-5
m.
8.33 x 10-5 m/s The ultrasound then enters bone where
the speed is 3400 m/s. What is the frequency of the sound in bone? 18MHz Calculate the wavelength of the sound in bone. 1.89 x10-4 m
