Quiz 3.1

A positive charge  $Q$  is placed very close to the positive plate of a parallel plate capacitor that produces an electric field  $E$ . Once released, the positive charge reaches the negative plate a distance  $d$  away with a kinetic energy of

•  $Ed$  

•  $QEd$  

•  $2Ed$  

•  $2QEd$  

Tags

NGSS.HS-PS3-5

A point charge  $-Q$  is placed a distance  $d$  from another point charge  $+2Q$ . How much work was required to place the negative charge at this location?

•  $-\frac{1}{4\pi\epsilon_0}\frac{Q}{d}$  

•  $\frac{1}{4\pi\epsilon_0}\frac{2Q}{d}$  

•  $-\frac{1}{4\pi\epsilon_0}\ \frac{2Q^2}{d}$  

•  $\frac{1}{4\pi\epsilon_0}\frac{2Q^2}{d}$  

How much potential energy is stored in a system of charges that consists of 3 charges, each with charge $+Q$  placed at the corners of an equilateral triangle of side length  $d$ ? 

•  $\frac{1}{4\pi\epsilon_0}\ \frac{Q}{d}$  

•  $\frac{1}{4\pi\epsilon_0}\ \frac{2Q}{d}$  

•  $\frac{1}{4\pi\epsilon_0}\ \frac{3Q}{d}$  

•  $\frac{1}{4\pi\epsilon_0}\ \frac{4Q}{d}$  

A student generates an equipotential map of a point charge and notices the electric potential decreases the further away from the charge. From only this information the student can determine which of the following?

• The charge is positive

• The charge is negative

• The magnitude of the charge

• Nothing, more information is required

A charge moves between two equipotential surfaces of 24 V to 15 V. If these surfaces are 2 cm apart, what is the magnitude of the average electric field in-between these surfaces?

• 0 V/m

• 4.5 V/m

• 450 V/m

• 45000 V/m

A positive charge  $+Q$  is placed a distance  $d$  from a negative charge  $-Q$ . Note these charges have the same magnitude but different sign. Which of the following is true about the electric field and the electric potential at a point midway between the two charges? 

• The electric field is zero and the electric potential is zero

• The electric field is not zero and the electric potential is zero

• The electric field is zero and the electric potential is not zero

• The electric field is not zero and the electric potential is not zero

Tags

NGSS.HS-PS2-4

NGSS.HS-PS3-5

A charge  $q$  with mass  $m$  is placed in a uniform electric field  $E$  and experiences a potential energy change of  $qEd$  as it moves between two points a distance  $d$  apart. Which of the following gives the velocity of the charge at this new location?

•  $\sqrt{\frac{qEd}{m}}$  

•  $\sqrt{\frac{2qEd}{m}}$  

•  $\frac{qEd}{m}$  

•  $\frac{2qEd}{m}$  

Tags

NGSS.HS-PS2-1

NGSS.HS-PS2-4

Which of the following is a correct expression for the potential energy of a charge placed near another charge?

• $qEd$

• $qE$

• $qV$

• $\frac{1}{4\pi\epsilon_0}\ \frac{Q}{r}$

These form a surface where the electric potential is constant everywhere on the surface.

• Gaussian surface

• Flux surface

• Equipotential lines

• Equatorial lines

An electron is placed on an equipotential surface of 20 V. On one side of this surface there is another equipotential surface of 16 V and on the other side there is an equipotential surface of 24 V. Towards which equipotential line will the electron move towards?

• Towards the 16 V line

• Towards the 24 V line

• Perpendicular to the page

• The electron will not move since there's an equal potential difference on both sides