Electricity/EM Spectrum/Light Final Study Guide
Remember to study the vocabulary words too!
Draw a diagram (using electric field lines) of two electric charges interacting.
1. Attraction
Field Lines coming together.
2. Repulsion
Field lines pushing apart.
Draw a diagram of a series circuit that has three resistors and a battery (use the
symbols from class).
Draw a diagram of a parallel circuit that has three resistors and a battery (use the
symbols from class).
Draw a diagram of an open circuit with a switch (use the symbols from class).
How is current related to resistance?
The amount of current in a circuit depends on the resistance in the circuit.
For a given voltage, the greater the resistance, the less the current in the
circuit.
List the three basic features of an electric circuit.
1. Source of electrical energy
2. Conducting path
3. Resistor
Write the formula for Ohm’s law showing how to solve for each variable.
V= IR
R= V/I
I= V/R
List and then describe how the four factors that affect resistance.
1. Material – conductors have loosely held electrons and insulators have
electrons that are tightly held to the atom.
2. Length – the longer the wire the higher the resistance, the shorter the wire
the lower the resistance. Electrons have more contact with the material
causing an increase in resistance.
3. Diameter – The greater the diameter, the lower the resistance. The smaller
the diameter, the higher the resistance.
4. Temperature – The higher the temperature, the higher the resistance. The
lower the temperature, the lower the resistance.
A toaster is plugged into a 120 V socket. If it has a current of 0.25 A in its coils,
what is the resistance of the toaster? Show your work.
R = V/I
R= 120V/0.25A = 480Ω
A circuit has a resistance of 15.2 Ω and a current of 0.10 A. What is the voltage of
the circuit? Show your work.
V = IR
V = 0.10A X 15.2Ω = 1.52V
What units are used to measure voltage, resistance, and current?
Voltage = volts = V
Current = amperes = A
Resistance = ohm = Ω
What is the rule for the interaction of magnetic poles and electric charges?
Opposites attract and likes repel
List three insulators and three conductors.
Insulators- Examples: glass, wood, rubber, Styrofoam, plastic
Conductors- Examples: tap water, gold, silver, copper, graphite
Identify and describe each method that can be used to transfer an electric
charge.
1. Friction = rubbing two objects together
2. Conduction = transfer of electrical charge by direct contact
3. Induction = the movement of electrons to one part of an object that is
caused by the electric field of a second object.
What event neutralizes two charged objects?
Static discharge
What do circuit breaker and fuses do in a house?
In order to prevent circuits from overheating and causing a fire, fuses and
circuit breakers are added to circuits.
What does the severity of a shock depend on?
Electric current
What is a short circuit and how can a person accidently become part of one?
A short circuit is a connection that allows current to take the path of least
resistance. Touching a downed power line or an exposed wire could cause a
person to receive a shock that could be fatal.
Describe what happens to the current and resistance in a series circuit when more
devices are added and the voltage remains constant?
If voltage remains constant and more resistors (devices) are added to a series
circuit, then resistance will increase and the electric current flowing through
the circuit will decrease.
Describe what happens to the current and resistance in a parallel circuit when
more devices are added and the voltage remains constant?
If voltage remains constant and more resistors (devices/branches) are added
to a parallel circuit, then the overall resistance of the circuit decreases and
the current flowing through the circuit will increase.
Define chemical reaction.
The process in which substances undergo chemical changes that result in the
formation of new substances.
A battery converts chemical energy in electrical energy.
How is voltage created in a battery?
Chemical reactions occur between the electrolyte and the electrodes in an
electrochemical cell. These reactions cause one electrode to becomes positively
charged and the other one to become negatively charged. Because the
electrodes have opposite charges, there is voltage between them.
Using a graphic organizer, compare and contrast series and parallel circuits. You
should have at least two similarities and a total of three contrasts (2 each).
Parallel – multiple paths for current to follow, one device out the rest stay on,
looks like rungs of a ladder, buildings are wired in parallel, as more branches
are added the overall resistance decrease and current increases
Series – one path for current to take, one device out and all devices are out,
looks like a circle, simple to build and design, as resistors are added the total
resistance increase and the current decreases
Similar – paths for current to follow, operates electrical devices, requires the
three basic features to be a circuit (path, resistor, power source)
Electromagnetic Spectrum
1. What is the difference between a mechanical wave (like sound) and an
electromagnetic wave?
2. Name the radiation of the electromagnetic spectrum in order of decreasing
wavelengths.
3. A decrease in wavelength, results in a __________________ in frequency.
4. Which have higher frequencies, radio or infrared?
5. Which has more energy, radio or infrared?
6. Which wave travels at a faster speed, radio or infrared?
7. Identify the colors of the visible spectrum ranging from lowest frequency to
highest frequency.
8. Why does sunlight feel warm to your skin?
9. The amount of _____________________ carried by an electromagnetic
wave ________________________ with ______________________.
Word bank for the above question (frequency, energy, increases, decreases,
speed, amplitude)
10. Which type of radiation has more energy, infrared, visible light, or
ultraviolet? WHY?
Light and Color
1. What are three things that can happen when light strikes an object?
a.
b.
c.
2. In which three categories can most materials be classified, based on what
happens to light that strikes the material?
a.
b.
c.
3. What happens to light that strikes a translucent material? Transparent
material? Opaque material?
4. What are the primary colors of light?
5. When combined in equal amounts, what do all three of the primary colors of
light produce?
6. Why is a blueberry blue?
7. What determines the color of an opaque object?
8. Why would a red apple with green leaves appear black through a blue filter?
9. What color light reflects all wavelengths of light?
10. What color of light absorbs all wavelengths of light?
Reflection and Mirrors
1. What are two kinds of reflections?
2. Explain how both types of reflections obey the law of reflection.
3. What is the difference between a real image and a virtual image?
4. What is a focal point?
5. Why are images produced by a convex mirror always virtual and reduced?
6. What is a good use for a convex mirror? Why?
7. Draw a Venn diagram and use the word bank below to compare and contrast
concave and convex mirrors.
Word Bank: reduced image, virtual images, curves outward, curves inward,
enlarged images, real images, focal point behind mirror, focal point in front of
mirror
Refraction/Lenses and Seeing Light
1.
What causes light rays to bend when they enter a new medium at an angle?
2. A____________________ lens is thicker in the center than at the edges. Light rays
parallel to the optical axis pass through and are _________________. This type of lens
produces a _____________________ image and a _____________________ image
depending on the location of the object relative to the ___________________ point.
3. A _________________________ lens is thinner in the center than at the edges. Light
rays parallel to the optical axis pass through the lens and are
_______________________. This causes light rays to never meet. This type of lens only
produces ______________________ images that are always upright and
_______________________ than the object.
4.
The ______________ of _____________________ is a measure of how much a ray of
light bends when it enters a material.
5. An object with a ___________________ index of refraction bends light the most.
6. The ____________ is a layer of cells that line the inside of the eyeball. This area is made
up of light sensitive cells called ______________ and _________________. Cells that
work in low levels of light are called the _____________. Cells that respond to color are
called ______________.
7. The type of lens found in the eye is a __________________ lens.
8. To correct nearsightedness, a _________________ lens is used in glasses/contact lenses.
To correct farsightedness, a _______________ lens is used in glasses/contact lenses.