Tuesday, February 21, 2017

Y12 Wave Questions

Maximum of 2 marks for correctly identifying the 4 errors OR stating the 2
correct notes:

i.e. errors in notes 1, 2, 3, and 6 (shown anywhere) B2

{5 or 6 or 2 or 1 notes nominated scores ZERO, 4 correct scores 2, 3 correct scores 1}

Valid corrections score 1 mark each: do not allow “NOT” corrections apart
from note 3

Note 1: In longitudinal waves vibrations are parallel to wave direction (WTTE) B1

{OR in transverse waves vibrations are perpendicular to wave
direction (WTTE}

Note 2 light (or any of the em waves) can travel through a vacuum (WTTE) B1

{allow sound/longitudinal waves cannot travel thro’ a vacuum}

Note 3: waves carry energy/disturbance (not displacement or info)
from…. (WTTE) B1

{allow “waves do not carry the medium” and “the medium carries
the waves from…….”}

Note 6: wavelength = distance from crest to crest/trough to trough/max
to max (WTTE)

Monday, January 30, 2017

Useful data

Speed of light = 300 000 000 m/s

Speed of radio waves = 300 000 000 m/s

Speed of sound in air = 340 m/s

The Wave Equation

Useful equations

Velocity = Frequency x wavelength

Velocity = distance travelled

Time taken

A water wave has a frequency of 2 Hz and a wavelength of 10cm (trap). Calculate its velocity. 0.2 m/s

A certain metal sound of wavelength 4.3 m has a frequency of 1500 Hz. Calculate its velocity. 6450 m/s

The frequency of a radio station is 1 200 kHz. What wavelength does it transmit on? 250m

A certain note has a wavelength of 15cm. Calculate its frequency.2266.7 Hz

A ray of light has a wavelength of 0.000 000 006m. Calculate its frequency. 5 x10¹⁴ Hz

A radio station broadcasts on 1760m. Calculate its frequency. 170 kHz

The lowest frequency that the human ear can detect is 20Hz (approx). 1.7m The highest is 20 kHz 1.7 mm(trap). Work out the wavelengths of these frequencies.

The distance between successive crests of a sea wave is 4 m. They pass a stationary observer every 20 seconds. What is the velocity of the wave?

Ripples pass along a pond. The distance between successive crests is 6 cm. The waves travel 0.5 m in 3 s. v=x/t =0.5/3 = 0.16m/s What is the wavelength in m 0.06m and the frequency? 2.67 Hz

Ripples pass along a pond at 0.3 m/s. What is their wavelength if the frequency is 6 Hz? 0.05m

Two people stand some distance apart on a railway line on a still day. One person puts her ear to the rail. The other hits the rail once with a sledge hammer. The listener hears two bangs, 1 second apart. Explain.

If the speed of sound in steel is 5500m/s calculate the distance between the listener and the hammerer. 362 m