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PRACTICAL ACTIVITIES (cont’d)
B. Stationary Microwaves

By moving the probe receiver find a number of consecutive nodes and hence measure the wave length.
Explain why this is better than trying to find the distance between two nodes. Use c=f? to find the
frequency of the microwaves
(c = 3.00 x 108 ms-1)
C. Stationary Sound Waves

(Note that this set-up will only yield an approximate value for the wavelength)

Find the distance between two consecutive nodes and, hence, find the wavelength of the sound. Find
v from v=f? . Repeat the experiment for a different frequency.

REFRACTION AND THE CRITICAL ANGLE

Refer to Unit 1, Module 2, Specific Objective 2.23 and 2.25

Aim: To investigate the refraction of light at an air/Perspex boundary and use the data
obtained to find the critical angle for light traveling from Perspex to air.

Method: Use pins to trace the passage of light through a semi-circular block of perspex for
various angles of incidence. Note that the light is incident on the flat face and you
must look at the alignment of the pins through the curved surface. [If available a
light box could be used to trace the rays instead of pins]

CXC A16/U2/07v01 82