I. Characteristics of Magnets Ch. 14 - Magnetism I. Characteristics of Magnets Magnetism Magnetic poles Magnetic field Magnetic domain 1

A. Magnetism Magnetism force of attraction or repulsion between unlike or like poles due to the arrangement of electrons closely related to electricity

B. Magnetic Poles Magnetic Poles like poles repel unlike poles attract a broken magnet creates new poles

C. Magnetic Field Magnetic Field area around a magnet where magnetic forces act field lines show direction of field (NS)

D. Magnetic Domain Magnetic Domain groups of atoms with aligned magnetic poles domain in a magnetized object, domains are all aligned

II. Uses of Magnetic Fields Electromagnet Speaker Motor Ch. 14 - Magnetism II. Uses of Magnetic Fields Electromagnet Speaker Motor 1

A. Electromagnet Electromagnet strong, temporary magnet formed when current is passed through a coil of wire surrounding an iron core acts like a bar magnet when current is on

B. Speaker Speaker electrical energy  mechanical energy wire coil moves back & forth as its magnetic field interacts with the field of a fixed magnet forced vibration causes the cone to move  sound

C. Motor Motor electrical energy  mechanical energy electromagnet rotates between the poles of a fixed magnet commutator reverses the poles of the e’magnet

brushes & wires to battery C. Motor assembled motor armature & commutator field magnet brushes & wires to battery

III. Producing Electric Current Ch. 14 - Magnetism III. Producing Electric Current Electromagnetic Induction Electric Generator DC & AC Transformer 1

A. Electromagnetic Induction producing a current by moving a wire through a magnetic field some microphones work just like mini-speakers in reverse sound waves cause coil to move  current Dynamic Microphone Coil

B. Electric Generator Electric Generator mechanical energy  electrical energy armature is rotated between magnet poles magnetic field induces a current in the wire coil GENERATOR MOTOR

B. Electric Generator Hydroelectric Dam PE of lake water is converted to KE mechanical KE turns the generator shaft which creates electrical energy

C. DC & AC Direct Current (DC) current flows in one direction dry cells Alternating Current (AC) current reverses its direction at regular intervals electrical outlets

D. Transformer Transformer increases or decreases AC voltage primary coil AC produces a magnetic field that induces AC in the secondary coil voltage ratio = ratio of turns in each coil

D. Transformer Step-up Transformer Step-down Transformer increases the voltage more turns power plants Step-down Transformer decreases the voltage fewer turns household appliances (hairdryers, etc.)

I. Electromagnetic Radiation Ch. 15 - Light I. Electromagnetic Radiation EM Radiation EM Spectrum Types of EM Radiation

A. EM Radiation Electromagnetic Radiation transverse waves produced by the motion of electrically charged particles does not require a medium speed in a vacuum = 300,000 km/s electric and magnetic components are perpendicular

A. EM Radiation Photons tiny, particle-like bundles of radiation absorbed and released by electrons energy increases with wave frequency

B. EM Spectrum long  low f low energy short  high f high energy

C. Types of EM Radiation Radiowaves lowest energy EM radiation

C. Types of EM Radiation Radiowaves FM - frequency modulation AM - amplitude modulation Microwaves penetrate food and vibrate water & fat molecules to produce thermal energy

C. Types of EM Radiation Infrared Radiation (IR) slightly lower energy than visible light can raise the thermal energy of objects thermogram - image made by detecting IR radiation

C. Types of EM Radiation Visible Light small part of the spectrum we can see ROY G. BIV - colors in order of increasing energy R O Y G. B I V red orange yellow green blue indigo violet

C. Types of EM Radiation Ultraviolet Radiation (UV) slightly higher energy than visible light Types: UVA - tanning, wrinkles UVB - sunburn, cancer UVC - most harmful, sterilization

C. Types of EM Radiation Ultraviolet Radiation (UV) Ozone layer depletion = UV exposure!

C. Types of EM Radiation X rays higher energy than UV can penetrate soft tissue, but not bones

C. Types of EM Radiation Gamma rays highest energy EM radiation emitted by radioactive atoms used to kill cancerous cells Radiation treatment using radioactive cobalt-60.