Microwaves that are vertically polarised are produced by a source. A receiver, linked to a cathode-ray oscilloscope (CRO), detects these microwaves. On the CRO screen, the displayed waveform has an amplitude of $2.6\,\text{cm}$. A metal wire grid acting as a polarising filter is then inserted between the source and the receiver. The filter is set so that the plane of polarisation of the transmitted wave makes an angle of $20^\circ$ with the vertical. The separation between the source and receiver stays the same. The CRO settings are also kept unchanged. What is the amplitude of the waveform now shown on the CRO screen?
- A$0.30\,\text{cm}$
- B$0.89\,\text{cm}$
- C$2.3\,\text{cm}$
- D$2.4\,\text{cm}$