Second Semester Final Exam Study Guide Flashcards
What is electric force?
The attraction or repulsion between electric charges.
What is an electric field?
A region around a charged object where the electric force is exerted. The closer the field lines, the stronger the force.
What is the difference between static and current electricity?
Static electricity is electricity that builds up on an object, but does not flow continuously. Current electricity is moving electrons (flowing).
How is current related to resistance?
The higher the resistance, the lower the current flow.
List the three basic features of an electrical circuit.
- Conducting path
- Power source
- Electrical device (load, resistor)
What does Ohm’s Law state?
Resistance = Voltage/Current
Voltage = Current x Resistance
Current = Voltage/Resistance
These three factors will affect how a current moves through a circuit.
List the four factors that affect resistance. Describe how they affect resistance.
- Material - Conductors have low resistance and insulators have high resistance.
- Length - Longer wires have more resistance than shorter wires.
- Diameter - Larger diameter wires have lower resistance compared to smaller diameter wires.
- Temperature - Higher temperatures increase the resistance and cooler temperatures decrease the resistance.
What units are used to measure voltage, resistance, and current?
- Voltage = Volts (V)
- Resistance = Ohms (ῼ)
- Current = Amperes (A)
What is the rule for the interaction of magnetic poles and electric charges?
Opposite poles/charges attract and similar poles/charges repel
List three insulators and three conductors of electricity.
Insulators - wood, plastic, glass
Conductors - vinegar, salt water, tap water
Describe how electric charges can be transferred by induction.
During induction, charges are separated by an electric field. When a charged object is brought near a neutral object the electric force within the field will separate positive and negative charges in the object (charging it).
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 devices are added, the resistance of the circuit will increase and the current 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 devices are added in parallel, then the overall resistance decreases and the current increases.
A battery converts ________ energy into __________ energy.
Chemical, electrical
What is voltage and how does it relate to current?
Voltage is the difference in electrical potential energy between two places in a circuit. Voltage can be thought of as the force pushing an electric current. The greater the voltage (difference in positive and negative) the greater the current can be.
How is voltage created in a battery?
Chemical reactions within the battery cause one side of the batter to become positively charged and the other side to become negatively charged.
What is the difference between a mechanical wave and an electromagnetic wave?
Electromagnetic waves do not require a medium to transfer energy.
Name the radiation of the electromagnetic spectrum in order of decreasing wavelengths.
Radio, microwave, infrared, visible, UV, X-Ray, Gamma
A decrease in wavelength results in an ________ in frequency.
Increase
Which have higher frequencies, radio or infrared?
Infrared
Which has more energy, radio or infrared?
Infrared
Which wave travels at a faster speed, radio or infrared?
Same, both are light
Identify the colors of the visible spectrum ranging from lowest frequency to highest frequency.
Red, orange, yellow, green, blue, indigo, violet.
Why does sunlight feel warm to your skin?
Because it contains infrared waves.
The amount of ______ carried by electromagnetic waves _________ with ________.
energy, increases, frequency
What type of radiation has more energy, infrared, visible light or ultraviolet? Why?
UV, because it has a higher frequency.
What are three things that happen when light strikes an object?
a. reflect
b. transmit
c. absorb
In which three categories can most materials be classified, based on what happens to light that strikes the material?
a. transparent
b. translucent
c. opaque
What happens to light that strikes a translucent material? Transparent material? Opaque material?
Translucent - light is scattered
Transparent - passes straight through
Opaque - reflected/absorbed
What are the primary colors of light?
Red, blue, green
When combined in equal amounts, what do all three of the primary colors of light produce?
White light
Why is a blueberry blue?
The blueberry is opaque so it reflects blue light and absorbs the rest.
What determines the color of an opaque object?
The color of light it reflects.
Why would a red apple with green leaves appear black through a green filter?
Red and green do not reflect blue wavelengths of light. The light is absorbed.
What color of light reflects all wavelengths of light?
White
What color absorbs all wavelengths of light?
Black
What are two kinds of reflection?
Diffuse and regular
Explain how both types of reflections obey the law of reflection.
Regular - light rays strike a smooth
