      Ms. Pearson's Science Site Things to know for 04-05 Semester #2 pg2    Home Physical Science Class Physical science LFC Semester Exams (Review) AP Enviromental Science science fair project  • Fixed pulley

 Does not multiply force. Changes the direction of the effort force. Mechanical advantage is equal to one.

• Movable pulley

 Multiplies effort force but cannot change direction of the effort force. Mechanical advantage is the effort distance divided by the resistance distance.

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• Wheel and axle  a lever that rotates in a circle around an axle.
• Two wheels of different sizes connected - the axle being the smaller wheel.
• EF applied to the wheel is multiplied at the axle.

• Electricity
• Properties and types of electric charge (positive, negative, what repels, what attracts)
• Electrostatic charge
• how objects become charged
• rubbing, contact with a charged object, induction
• (gaining electrons or losing electrons, moving electrons within the object)
• Electrical force
• Coulomb’s Law of electrostatics: dependence on charge and distance
• Similarities and differences from gravitational force
• Electric field
• electric potential (potential energy per unit charge, units: volts)
• electric potential difference (difference in electric potential between two points, units: volts)
• electric current (units: Amperes (or Amps))
• electric circuits
• how to make (what must be the case to have an electric circuit?)
• definition of resistance (units: Ohms)
• Ohm’s Law
• Series and parallel circuits (how they work, how to find V, I, R, P in different circuits)
• How to find equivalent resistance of complex (more than one resistor) circuits
• Electric power (P = IV = energy/time)
• Which is more dangerous- high voltage or high current flow?
• conductors, insulators, semi-conductors
• Magnetism
• magnetic poles (north, south, what repels, what attracts)
• magnetic force, magnetic field, dependence of force on distance
• Magnetic domains, what makes an object "magnetic"
• Ferromagnetic, paramagnetic, and diamagnetic materials
• Relationship between electric and magnetic fields
• moving charges (current) produce a magnetic field (electromagnet)
• magnetic fields affect moving charges
• changing magnetic fields induce a current (electromagnetic induction)
• light (electromagnetic radiation) is a self-propagating electromagnetic disturbance
• Important general concepts:
• Like charges (or magnetic poles) repel, opposite charges (or magnetic poles) attract
• An object in which a charge has been induced behaves like a charged object even though there is
• no net positive or negative charge on the object.
• The concept of a force field helps us quantify the effect of forces which act at a distance for any
• point in space.
• Electric fields and magnetic fields are intimately related.     