A student is investigating portable green-energy devices. One device is a kinetic "shake-to-charge" emergency torch.
Shaking the torch back and forth produces an alternating current (a.c.) inside its internal coil, which is used to charge an energy-storage capacitor.
What is alternating current?
The torch contains an indicator light that emits visible green light.
Suggest a reason why visible light, rather than ultraviolet radiation, is used for user indicator lights on portable devices.
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 |
|---|---|---|
| X-rays | ||
| Microwaves |
The diagram shows the internal construction of the shake-to-charge torch.
Describe how shaking the torch back and forth produces an electrical current in the coil to charge the device.
