Electric Forces and Fields

Which of the following best characterizes electrical conductors?

• low mass density

• high tensile strength

• electric charges move freely

• poor heat conductors

Two-point charges are 4 cm apart. They are moved to a new separation of 2 cm. By what factor does the resulting mutual force between them change?

• 1/2

• 2

• 1/4

• 4

Tags

NGSS.HS-PS2-4

Two-point charges, separated by 1.5 cm, have charge values of +2.0 µC and -4.0 µC, respectively. What is the value of the mutual force between them?

• 320 N

• 3.6 x 10^-8 N

• 8.0 x 10^-12 N

• 3.1 x 10^-3 N

Tags

NGSS.HS-PS2-4

A 6.0 µC charge is placed at the origin and a second charge is placed on the x-axis at x = 0.30 m. If the resulting force on the second charge is 5.4 N in the positive x-direction, what is the value of its charge?

• 9.0 µC

• 9.0 nC

• –9.0 µC

• –9.0 nC

Tags

NGSS.HS-PS2-4

Electric field is dimensionally equivalent to which of the following?

• Nm/C

• N/C

• Nm²/C²

• N/C²

Tags

NGSS.HS-PS2-4

NGSS.HS-PS3-5

Two point charges are placed along a horizontal axis with the following values and positions: +3.0 µC at x = 0 cm and -7.0 µC at x = 20 cm. At what point along the x axis is the electric field zero?

• 8.0 cm

• -44 cm

• -69 cm

• -38 cm

Tags

NGSS.HS-PS2-4

Two charges, +Q and -Q, are located two meters apart and there is a point along the line that is equidistant from the two charges as indicated. Which vector best represents the direction of the electric field at that point?

• Vector E_A

• Vector E_B

• Vector E_C

• The electric field at that point is zero.

Tags

NGSS.HS-PS2-4

A charge of +2 C is at the origin. When charge Q is placed at 2 m along the positive x axis, the electric field at 2 m along the negative x axis becomes zero. What is the value of Q?

• -3 C

• -6 C

• -7 C

• -8 C

Tags

NGSS.HS-PS2-4

NGSS.HS-PS3-5

Two point charges, separated by 1.5 cm, have charge values of +2.0 µC and -4.0 µC, respectively. Suppose we determine that 10 field lines radiate out from the +2.0 µC charge. If so, what might be inferred about the -4.0 µC charge with respect to field lines?

• 20 radiate out

• 5 radiate out

• 20 radiate in

• 10 radiate in

Tags

NGSS.HS-PS3-5

We have an initially uncharged hollow metallic sphere with radius of 5.0 cm. I place a small object with a charge of +10 µC at the center of the sphere through a hole in the surface. Find the electric field present at a point 10 cm from the sphere’s center. (k_e = 8.99 ´ 10⁹ N×m²/C²)

• 1.1 x 10⁶ N/C

• 2.3 x 10⁶ N/C

• 9.0 x 10⁶ N/C

• 36 x 10⁶ N/C

Tags

NGSS.HS-PS2-4