physics revision

1. the spreading of waves when they pass through a gap or around the edges of an obstacle which has a similar size as the wavelength of the waves
4. reflection of sound that can be heard
5. sound wave at the frequency greater than 20000HZ
8. electric and magnetic disturbances that transfer energy from one place to another
11. electrical device that is used to step up the size of an alternating voltage
12. the process in which small nuclei are forced together so they fuse with each other to form a larger nucleus
13. vibration that travels through a substance
14. move to and from about a certain position along a line
15. electrical device used to charge an alternating voltage
16. a force can change the motion of an object

2. electromagentic waves between visible light and microwaves in the electromagnetic spectrum
3. increase in the wavelength of electromagnetic waves emitted by a star or galaxy due to its motion away from us
6. the network of cables and transformers used to transfer electricity from power stations to consumers
7. stretched apart
9. tiny positively charged object composed of protons and neutrons at the centre of every atom
10. electrical device that is used to step down the size of an alternating voltage
11. distance moved divided by time taken