A comprehensive review lesson for a Physics unit on Electric Forces, covering atomic structure, electric fields, Coulomb's Law calculations, and real-world applications of electrostatics.
What happens to the negative charges in the soil as the negative cloud base approaches? How does this change the surface charge of the ground?
Question B: Lightning Rods
Metal
Resistivity (\( 10^{-8} \, \Omega\text{m} \))
Lead
22.0
Copper
1.68
Iron
9.75
Why is Copper the best choice for a lightning rod? Reference the table.
B. 1.0 m
C. 10 m
D. 100 m
09
An object becomes charged without making physical contact with another charged object. This process is called:
A. Conduction
B. Induction
C. Friction
D. Polarization
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10
A student calculates the force between an electron and a proton separated by \( 5.3 \times 10^{-11} \text{ m} \). The resulting force should be:
A. Attractive, because they have opposite charges.
B. Repulsive, because they have opposite charges.
C. Zero, because an atom as a whole is usually neutral.
D. Attractive, because electrons are larger than protons.
11
During a lightning strike, the ground beneath the negative cloud base becomes positively charged. This induction occurs because:
A. Protons are attracted from deep soil layers up to the surface.
B. Electrons on the surface are repelled deeper into the Earth.
C. The cloud shoots protons at the ground to neutralize it.
D. The ground loses its neutrons to the ionizing air.
12
Which of the following materials would be the POOREST choice for a lightning rod based on its resistivity?
A. Copper
B. Silver
C. Rubber
D. Aluminum
13
The Law of Conservation of Charge implies that:
A. Charge can be created from scratch if enough energy is applied.
B. The total amount of charge in an isolated system remains constant.
C. Positive charges always naturally outnumber negative charges.
D. Charge only exists when objects are in physical motion.
14
Which quantity is defined as the electrostatic force per unit charge (\( F/q \)) at a given point?
A. Electric Potential
B. Magnetic Field
C. Electric Field Strength
D. Gravitational Force
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15
If you double the charge of both objects AND double the distance between them, the resulting force:
A. Stays the same
B. Doubles
C. Halves
D. Quadruples
16
Which vector diagram correctly represents the electrostatic forces between two protons?
Choice A
Choice B
17
A neutral metal sphere is touched by a negatively charged rod. As a result, the sphere:
A. Gains electrons and becomes negatively charged.
B. Gains protons and becomes positively charged.
C. Loses electrons and becomes positively charged.
D. Remains neutral but becomes permanently polarized.
18
The SI unit for electric charge is named after which scientist?
A. Newton
B. Ampere
C. Volta
D. Coulomb
19
Two point charges are separated by distance \( d \). If the distance is reduced to \( d/2 \), the force between them becomes:
A. \( 2F \)
B. \( 4F \)
C. \( F/2 \)
D. \( F/4 \)
20
Which statement best describes the primary function of a lightning rod?
A. To capture and store electrical energy from the clouds.
B. To prevent lightning from discharging in the surrounding atmosphere.
C. To provide a low-resistance path for charge to reach the ground safely.
D. To increase the building's electrical resistance.
End of Mock Exam • Unit 6 Assessment Prep
Bringing a negatively charged balloon near a neutral wall without touching it, causing the wall's surface to polarize.
Conduction Induction Friction
Station 6
Lightning Physics
Task: Analyze the real-world application of electrostatics.
During a storm, the bottom of a cloud becomes heavily NEGATIVELY charged. The ground below is neutral, but the cloud's charge causes the ground to become POLARIZED.
Question:
Does the negative cloud attract or repel the electrons in the soil? What charge is left at the very surface of the ground?
