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Lesson: Force on a Charge Due to an Electric Field

Sample Question Videos

Worksheet • 15 Questions • 1 Video

Q1:

A proton moving horizontally at 1 . 3 Γ— 1 0 7 m/s enters a region containing a uniform electric field produced by two charged plates. The electric field is modeled as being of uniform strength over the 12.0 cm length of the plates, as shown in the diagram. The magnitude of the electric field in the region is 3 . 5 Γ— 1 0 5 N/C. By what distance 𝑑 is the proton deflected downward in its passage through the region containing the field?

  • A 1 . 4 Γ— 1 0 βˆ’ 3 m
  • B 9 5 Γ— 1 0 βˆ’ 3 m
  • C 3 . 6 Γ— 1 0 βˆ’ 3 m
  • D 7 8 Γ— 1 0 βˆ’ 3 m
  • E 9 8 0 Γ— 1 0 βˆ’ 3 m

Q2:

An electron has a velocity of 5 . 0 0 Γ— 1 0 6 m/s when it reaches a point 𝑃 , which is the point at which the electron enters a uniform electric field of magnitude 2 . 0 0 Γ— 1 0 5 N/C, directed oppositely to the initial velocity of the electron. The electron is decelerated by the field until it comes instantaneously to rest and is then accelerated in the opposite direction to its initial velocity.

How much time passes between the electron reaching the point 𝑃 and coming instantaneously to rest?

  • A 1 . 4 2 Γ— 1 0 βˆ’ 1 0 s
  • B 4 . 0 5 Γ— 1 0 βˆ’ 9 s
  • C 4 . 4 2 Γ— 1 0 βˆ’ 9 s
  • D 6 . 2 1 Γ— 1 0 βˆ’ 1 0 s
  • E 1 . 1 4 Γ— 1 0 βˆ’ 9 s

What is the velocity of the electron when it returns to the point 𝑃 ?

  • A βˆ’ 5 . 0 0 Γ— 1 0 6 m/s
  • B βˆ’ 5 . 7 5 Γ— 1 0 6 m/s
  • C βˆ’ 2 . 2 0 Γ— 1 0 6 m/s
  • D βˆ’ 3 . 4 1 Γ— 1 0 6 m/s
  • E βˆ’ 2 . 5 0 Γ— 1 0 6 m/s

Q3:

Two charged conductive spheres of radii 𝑅 = 2 . 5 1 cm and 𝑅 2 , respectively, are connected by a wire, as shown in the diagram. A value of 𝑅 2 is chosen that will result in an electric field of magnitude 2 . 3 Γ— 1 0 6 V/m at the surface of the smaller sphere when the larger sphere is placed in an electric field of magnitude 302 V/m. Find 𝑅 2 .

  • A 3 . 3 Γ— 1 0 βˆ’ 3 cm
  • B 1 . 5 Γ— 1 0 βˆ’ 3 cm
  • C 2 . 3 Γ— 1 0 βˆ’ 3 cm
  • D 5 . 2 Γ— 1 0 βˆ’ 3 cm
  • E 4 . 2 Γ— 1 0 βˆ’ 3 cm
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