先进材料疑固实验室 State of matter Laboratory of Advanced Materials Solidification In a solid,the particles(ions,atoms or molecules)are closely packed together.The forces between particles are strong so that the particles cannot move freely but can only vibrate. A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a(nearly)constant volume independent of pressure.The volume is definite if the temperature and pressure are constant. A gas is a compressible fluid.Not only will a gas conform to the shape of its container but it will also expand to fill the container. Like a gas,plasma does not have definite shape or volume.Unlike gases,plasmas are electrically conductive,produce magnetic fields and electric currents and respond strongly to electromagnetic forces. 上浒充通大学 SHANGHAI JIAO TONG UNIVERSITYState of matter In a solid, the particles (ions, atoms or molecules) are closely packed together. The forces between particles are strong so that the particles cannot move freely but can only vibrate. A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. The volume is definite if the temperature and pressure are constant. A gas is a compressible fluid. Not only will a gas conform to the shape of its container but it will also expand to fill the container. Like a gas, plasma does not have definite shape or volume. Unlike gases, plasmas are electrically conductive, produce magnetic fields and electric currents and respond strongly to electromagnetic forces