A field seismologist is investigating the detection and recording of ground vibrations.
The geophone is connected to a recording unit. The electrical signal produced by the vibrating geophone is an alternating current (a.c.).
State what is meant by alternating current.
Seismic data can be transmitted wirelessly from the field to a base station using microwaves.
Suggest a property of microwaves that makes them suitable for satellite or line-of-sight terrestrial communication.
Complete the table to show uses and possible harmful effects of some other parts of the electromagnetic spectrum.
| Part of electromagnetic spectrum | Use | Possible harmful effect on people |
|---|---|---|
| ultraviolet | ||
| X-rays |
Ground vibrations are detected using an electromagnetic geophone.
The diagram shows the construction of a vertical geophone.
Describe how a geophone uses ground vibrations to produce an electrical signal.
