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Across 4. A family of different frequencies (8) 6. the property of bones allowing the absorption of x-rays (7) 10. when light changes direction due to a change in speed (10) 14. to allow an EM ray to pass through (8) 15. Light intensity falls as you go from a source by the _________ square law. (7) 17. when two variables appear to be linked together (11) 20. Speed of light is 3 x 10 ^ _________ m / s (5) 21. the distance from one part of a wave to the next similar part (10) 23. the type of EM wave emitted by the earth (8) 24. unwanted signal (5) 25. being in a position to absorb radiation (8) 26. an electromagnetic wave to be recieved (6)

Down 1. when one event directly results in another event happening (5) 2. what water, oil, glucose and fat molecules do in a microwave (8) 3. the desired outcome of taking a risk (7) 5. a potent greenhouse gas (7) 7. A measure of how quickly a wave oscillates (9) 8. Energy per unit area per second (9) 9. the property not transmitting visible light (6) 11. when an atom is stripped of an electron (10) 12. to increase the strength of a signal (7) 13. to 'take in' an EM ray (6) 16. the highest energy visible light colour (6) 18. the science to prove a causal relationship (9) 19. a packet of light energy (6) 22. to 'clean' a signal of unwanted noise (6)