CHARGE!
An atom gains electrons. What happens to its overall charge and why?
It becomes negatively charged.
Atoms are overall neutrally charged, so if an atom gains extra electrons then it becomes negatively charged
What is an electric field?
An electric field is a region around an electric charge where other charges feel an electric force. Its like an invisible “force field” created by charged objects. If another charge enters that space, the field pushes or pulls on it. Electric fields help explain how charged objects can attract or repel each other without touching.
What is a subatomic particle? Give three examples of subatomic particles that we've talked about in class.
A subatomic particle is simple a particle that is smaller than an atom. The three subatomic particles that we talked most about in class are the proton, neutron, and electron. There are others that you could name, but those are the most relevant ones to what we discussed this unit.
Static electricity involves:
A) continuous charge flow
B) charge buildup/separation
C) moving protons
D) neutral atoms only
Correct answer: B
Static electricity involves charge building up or separating in one place, rather than continuously flowing through a circuit.
What is/are the minimum requirement(s) for a bulb to light in a circuit?
1) there must be a power source (like a battery) and 2) the circuit must be closed (for example, a complete loop of wire needs to connect the terminals of the bulb to the terminals of a battery in a way that allows electrons to flow in a circle)
Two objects repel each other. What can you conclude about their charges?
They must have the same type of charge.
Like charges repel. So that means the two charges could either be + and + or - and -.
A positive “test charge” is placed near a large negative charge. Which direction will the force vector point on the test charge?
Toward the negative charge.
The two charges are attracted to each other, so the positive test charge is drawn towards the negative charge. This is similar to electric field lines. The direction of the electric field lines indicates the direction of the electric force on a positive test charge.
What are the units used to measure voltage, current, and resistance? What letters/symbols do we use to represent them?
Voltage is measured in Volts (V)
Current is measured in Amps (A)
Resistance is measured in Ohms (Ω)
Why might two pieces of tape repel each other after being pulled apart?
When two pieces of tape are pulled apart, electrons can transfer from one tape to the other. This leaves both pieces with electric charges. If the two pieces end up with the same type of charge, they repel each other because like charges push away from each other.
Quick! Get a bulb, a battery, and two wires. Build a circuit that works. You have 30 seconds starting now!
If your bulb illuminated then you get points!
...But you also have to explain why your circuit works to get full points :)
What is a “charge carrier,” and why are electrons usually the charge carriers in electricity?
A charge carrier is something that can move and carry electric charge. Electrons are usually the charge carriers because they are located outside the nucleus of the atom and can move between, or be torn off from, atoms fairly easily. Protons also have charge, but they are trapped tightly inside the nucleus, so they usually cannot move through materials or across materials.
A negatively charged balloon and a positively charged balloon are placed near each other. What will happen to the balloons, and how do electric fields explain this behavior?
The balloons will attract each other because opposite charges attract. The positive balloon creates an electric field that pulls on the negative balloon, and the negative balloon creates an electric field that pulls on the positive balloon.
What is resistance? Define the term and then explain what the resistance of an insulator would be, and what the resistance of a conductor would be.
Resistance is how much a material or object opposes the flow of electric current. Higher resistance makes it harder for charge to flow. Lower resistance makes it easier for charge to flow. The resistance of an insulator would be very high (usually taken to be infinity). The resistance of a conductor would be very low (usually taken to be zero).
What is one important similarity between static electricity and current electricity? What is one important difference between static and current electricity?
Both involve electric charges and electric forces.
Static electricity involves charge buildup; current electricity involves continuous charge flow.
[See image] Uh oh! A student tried to make a circuit that lights a bulb but it failed. List at least two things that are wrong with their circuit, and then draw a picture of the correct way to make their circuit (include all components shown)
1) The batteries are not connected to anything
2) Two wires are connected to a single terminal on the switch.
(other answers are also possible)
Come up and draw your correct circuit to get full points!
Two objects attract each other. What can you conclude about their charges? Be specific and complete in your answer.
There are three valid possibilities that could be true.
1) Either the charges are opposites (one is - and the other is +
2) One is + and the is neutral
3) One is - and the other is neutral
[see image]
What is wrong in this picture?
The shape of the field lines is correct, but the direction of the field lines is wrong! Electric field lines should always point out of + and in to - ...and these do not!
List five materials that are good conductors and five materials that are good insulators. Then try to think of one material that is... somewhere in-between. Its neither a good or bad conductor.
There are many possible answers here!
Is lightning an example of static electricity, current electricity, both, or neither? Explain.
Lightning is caused by electrostatic charge buildup followed by current flow... so its involves both static electricity and momentary current electricity.
A spark from static electricity lasts only a tiny fraction of a second, while the current in a flashlight can flow continuously for hours. Explain why one situation is brief and the other can continue for a long time.
A static spark is brief because it comes from a buildup of separated charge that quickly discharges all at once. Once the extra charge has moved, the spark stops. A flashlight can keep current flowing because the battery continuously provides energy that pushes charges through the circuit for a long time.
Explain why BOTH positively charged and negatively charged objects attract neutral objects.
Charged objects can attract neutral objects because they cause charges inside the neutral object to shift slightly. This creates an opposite charge closer to the charged object, causing attraction.
If electric field lines are packed closely together in one region, what does that mean?
Closely packed electric field lines represent a stronger electric field. You can see this by looking at the field lines around a charged object. Near the charge, the field lines are drawn closer together, and the electric force is also stronger there. Farther away, the field lines spread out, and the force becomes weaker.
Two circuits both contain: one bulb, one battery, connecting wires. In Circuit A, the bulb glows brightly. In Circuit B, the bulb glows only very dimly. Give TWO different possible reasons why Circuit B might be dimmer, and explain how each reason affects the flow of charge in the circuit.
Possible answers include:
- Circuit B could have a lower-voltage battery. Lower voltage provides less push on the charge carriers, so less current flows and the bulb is dimmer.
- Circuit B could have a bulb with higher resistance. Higher resistance makes it harder for charges to flow, reducing current and brightness.
- Circuit B could contain a wire made from a poor conductor (like steel), which would also reduce current flow.
- Circuit B could have a loose or weak connection that increases resistance and reduces current.
Why is static electricity usually associated with insulators, while current electricity is usually associated with conductors?
Static electricity is usually associated with insulators because charges cannot move easily through them, so charge can build up and stay separated in one place.
Current electricity is usually associated with conductors because conductors contain charge carriers that can move freely, allowing charges to continuously flow through a circuit.
Three simple circuits each contain one battery and one light bulb:
Circuit A: 1.5 V battery, 8 Ω bulb
Circuit B: 3 V battery, 8 Ω bulb
Circuit C: 3 V battery, 4 Ω bulb
Rank the bulbs from dimmest to brightest. Assume brighter bulbs have more current flowing through them.
Circuit A is dimmest, B is brighter, and C is brightest.
Higher voltage increases current, while higher resistance decreases current. Since brighter bulbs have more current, A < B < C.