Electrostatics
What do opposite and like charges do?
Opposite charges attract. Like charges repel.
Is resistance lower in wet skin or dry skin?
Wet skin because water is a conductor that makes it easier for current to flow.
If you put a compass in a magnetic field, why way will it point?
The compass will point North.
What is a period
Is the amount of time it takes to complete one oscillation (movement back and forth).
What are the primary and secondary colors of light?
Primary colors = red, green, blue
Secondary colors = yellow, cyan, magenta
What are conductors and insulators? Provide examples.
Conductors = are materials that permit electrons to flow freely from particle to particle.
ex: water, people, metal
Insulator = are materials that impede the free flow of electrons from atom to atom and molecule to molecule.
ex: wood, plastic, cloth, rubber
Are houses wired in series or parallel circuits?
Houses are wired in parallel circuits.
Can you produce a magnetic field with a charge that is not moving?
No, because velocity is needed to create a magnetic field.
What are beats?
Two notes at the same/ similar frequency. A person then hears a pulsing noise.
Describe total internal reflection.
Light rays pass from medium to lower index of refraction. The rays are then completely reflected only if the angle of incidence is large enough.
What is the electric field inside a metal sphere?
The field inside is zero because the charge is around the surface of the sphere while inside there is no charge.
What is a short circuit?
When there is no resistance in the circuit. The wires are directly connected to the battery (voltage source). This creates a high current that combined with no resistance generates high heat that can produce an electrical fire.
Explain the 2nd RHR rule for a charge moving in a magnetic field.
Thumb = Force
Pointer = Direction of current
Curled fingers = magnetic field
Explain the difference between transverse waves and longitudinal waves.
Transverse waves = are perpendicular to the direction of the wave.
ex: visible light
Longitudinal waves = same direction of the wave
ex: sound
What kind of lenses are used to correct nearsighted and farsighted vision?
Concave lens are used to correct nearsightedness because these lenses increase the focal length. Convex lens are used to correct farsightedness by reducing the focal length.
What are the methods of charging?
Friction Charging = rubbing objects together to transfer charge from one object to another.
Conduction Charging = an object makes physical contact with a charged object.
Induction = a neutral object becomes charged without physical contact with a charged object.
What is the 3rd hole in some outlets used for?
The 3rd prong is called "ground" that is wired to the earth that provides a safe route for excess current to flow so that people do not get shocked.
What is magnetic flux?
Refers to the amount of magnetic field passing through a surface area.
What is the Doppler effect?
Refers to the change in frequency of sound caused by the movement of the course or detector. The sound is condensed and spread apart that causes a change in pitch.
ex: Ambulance
What are mirages?
the deceptive appearance of a distant object or objects caused by the bending of light rays (refraction) in layers of air of varying density
How do microwave ovens work?
Microwaves cook food through electromagnetic radiation. The electric field changes direction very quickly that polarized molecules like water. These molecules line up in the changing electric field. The produce thermal energy and heat up the food.
What are some safety features in homes to prevent too much current from coming in?
Ground outlets, Ground fault circuit interrupter (GFCI), Fuses/ Breakers
What is the difference between a motor and a generator?
An electric motor converts electricity into mechanical energy, providing a power source for machinery. A generator does the opposite of this, converting mechanical energy into electricity
What is resonance? Give an example.
Object vibrates at its natural frequency. The amplitude of the wave increases to a point of destruction.
ex: Tacoma Bridge collapse, breaking wine glass with someones voice
What does lenses do to light rays?
Convex lenses = converge light rays
Concave lenses = diverge light rays