REY MAR AQUINO 24

An electron moves from point i to point f, in the direction of a uniform electric field. During this displacement:

• work done by the field is negative and the potential energy of the electron-field system increases

• work done by the field is positive and the potential energy of the electron-field system increases

• the work done by the field is positive and the potential energy of the electron-field system decreases

• the work done by the field is negative and the potential energy of the electron-field system decreases

• the work done by the field is positive and the potential energy of the electron-field system does not change

Choose the correct statement:

• A proton tends to go from a region of low potential to a region of high potential

• The potential of a negatively charged conductor must be negative

• If En = 0 at a point P then V must be zero at P

• . V = 0 at a point P then En must be zero at P

• None of the above are correct

An electron is accelerated from rest through a potential difference V . Its final speed is proportional to:

• V

• V^2

• 1/V

• sqrt V

• 1/sqrt V

In separate experiments, four different particles each start from far away with the same speed

and impinge directly on a gold nucleus. The masses and charges of the particles are

particle 1: mass m0, charge q0

particle 2: mass 2m0, charge 2q0

particle 3: mass 2m0, charge q0/2

particle 4: mass m0/2, charge 2q0

Rank the particles according to the distance of closest approach to the gold nucleus, from

smallest to largest.

• 1, 2, 3, 4

• 4, 3, 2, 1

• 3, 1 and 2 tie, then 4

• 4, 1 and 2 tie, then 1

• 1 and 2 tie, then 3, 4

Two large parallel conducting plates are separated by a distance d, placed in a vacuum, and connected to a source of potential difference V . An oxygen ion, with charge 2e, starts from rest on the surface of one plate and accelerates to the other. If e denotes the magnitude of the electron charge, the final kinetic energy of this ion is:

• eV/2

• eV/d

• eVd

• Vd/e

• 2eV

An electron volt is :

• the energy gained by an electron in moving through a potential difference of 1 volt

• the force acting on an electron in a field of 1 N/C

• the force required to move an electron 1 meter

• the work done when 1 coulomb of charge is moved through a potential difference of 1 volt.

• the energy needed to move an electron through 1 meter in any electric field

An electron has charge −e and mass me. A proton has charge e and mass 1840me. A “proton volt” is equal to:

• 1eV

• 1840eV

• (1/1840)eV

• (sqrt1840)eV

• (1/sqrt1840)eV

Two conducting spheres are far apart. The smaller sphere carries a total charge Q. The larger

sphere has a radius that is twice that of the smaller and is neutral. After the two spheres are connected by a conducting wire, the charges on the smaller and larger spheres, respectively,

are:

• Q/2 and Q/2

• Q/3 and 2Q/3

• 2Q/3 and Q/3

• zero and Q

• 2Q and −Q

A conducting sphere with radius R is charged until the magnitude of the electric field just

outside its surface is E. The electric potential of the sphere, relative to the potential far away,

is:

• zero

• E/R

• E/R^2

• ER

• ER^2

A hollow metal sphere is charged to a potential V . The potential at its center is:

• V

• 0

• -V

• 2V

• pieV