Electrostatics and Electromagnetism

Question 1

Coulomb’s Law

Answer 1

• F = (k |q₁| |q₂|)/r²
• The magnitude of the electrical force F that each of the two charges exerts on the other can be expressed in terms of the above equation
• Like charges will repel, while opposite charges will attract

Question 2

Electric Field

E = ?

Answer 2

• An electric field is a region of space where a charged particle would feel an electrostatic force, if it were moved there
• Electric field lines emenate from the + charge and travel to the - charge
• Distance between the field lines is inversely proportional to the strength of the field at that point
• E = F/q’
  
  • The ratio of the net electrical lforce F acting on a test charge to the value of the charge

Question 3

Movement of Charges

Answer 3

• • charges move in the direction of field lines, towards the - charge
• • charges move in the opposite direction of field lines, towards the + charge

Question 4

Equipotential Lines

Answer 4

• An equipotential line connects all poinots within an electric field sharing the same potential
  
  • No work is done by moving a charge along said equipotnetial line

Question 5

Electric Potential Energy

Answer 5

• ΔPE = kq₁q₂(1/r_f - 1/r_i)
• The electrical potential energy of particles with like charges increases when the charges are brought towards eachother; EQP of opposite charges decreases when brought close toghether
• Generally speaking if you must do work to move the charged particles, then they’ve been moved to a state of higher electrical potential energy

Question 6

Electrical Potential Difference

Answer 6

• The electrical potential difference a moving charged particle is subjected to as it moves from some region A to some region B is the difference in electrical potential energy ΔPE_q at those two regions, divided by the value associated with the charged particle q
  
  • V_AB = ΔPE_AB/q = (PE_qB - PE_qA)/q
  • ΔPE_q = qV

Question 7

Dielectric Constant

Answer 7

• Dielectrics are placed between two charged plates, effectively decreasing the net electric field
• F_medium = F_vacuum/K
• As the dielctric constant increases, the capicitor becomes more polarized

Question 8

Electric Dipole

Answer 8

• An electric dipole is created when two charges of opposite signs are separated from one another by some distance L
• p = qL
  
  • q = product of the charge

Question 9

Magnetic Fields

Answer 9

• Magnetic fields, B, are genearted from charges moving through space
• Magnetic field lines emenate from the north pole and travel to the south pole
• F_mag = qvB_{perpendicular}

Question 10

Right Hand Rule

Answer 10

1. Thumb point in the direction of charge movement
2. Fingers point in the direction of the magnetic field lines
3. Palm points in the direction of the resultant magnetic force
   
   1. For a negative charge, flip the direction of the resultant magnetic force

Question 11

Lenz’s Law

Answer 11

• When a conducting loop experiences a change in the magntic flux within its boundaries, a current will be induced in the loop that creats a magnetic flux opposing the change in the external magnetic flux
• Think Le Châtlier

Question 12

Induced Current in a Loop

Answer 12

• Counterclockwise current will generate field lines pointing out of the page
• Clockwise current will generate field lines pointing into the page

Question 13

Faraday’s Law

Answer 13

• States that as you increase the rate at which the loop enters a B field, the magnitude of the induced current increases

Question 14

Solenoid

Answer 14

• A solenoid is helical winding of a conducting wire; when a current is passed though, a magnetic field can be generated

Question 15

Mass Spectrometer

Answer 15

• F_radial = mv²/r = qvB
• r = mv/qB