Microwave ovens, mobile phones, radar Use this information to decide which set of results were more valid: A more valid set of results only changes one variable. The results are valid because the experiment is a fair test. If another variable changes, the validity decreases. Use this information to decide which set of results were more reliable: A more reliable set of results Have been repeated. The more repeats you do, the more reliable the result becomes. Use this information to write a definition of an isotope: Two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element. Particle Mass Charge Proton 1 +1 Neutron None Electron 1/2000 -1 Use this information to write a description of the electromagnetic spectrum: The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object. Part of the EM spectrum Wavelength Frequency Sources Radio waves    103 metres  1-1000 MHz  AM radio transmitters Microwaves  10-2 metres  1010 Hz  Microwave ovens, mobile phones, radar Infra red  10-5 metres  1013 Hz  Remote controls Visible light  0.5-6 metres  1015 Hz  Light bulbs, the sun Ultraviolet  10-8 metres  1016 Hz  The sun, black lights X rays  10-10 metres  1018 Hz  X-ray machines Gamma rays  10-12 metres  1021 Hz  Radioactive elements Use this information to describe how DNA can influence characteristics: In the nucleus the DNA present consists of many base pairs. When mRNA is made by producing a complementary strand, different bases are paired with the DNA strand. Each three bases is known as a triplet. A triplet is the code for one amino acid. Different triplets code for different amino acids. When different amino acids are joined together in the ribosome, a protein is produced. Different proteins contain different amino acids in unique sequences. Because everyone’s DNA is unique, different proteins will be made by everyone. This means that each cell will have individual characteristics. For instance, if someone has DNA that codes for a blue protein, you may have blue eyes. If you have DNA that codes for a brown protein, you may have brown eyes.