final exam

what does it mean if an object has a positive charge?

it means it has more protons than electons

the antimatter counterpart of the electron has…

a positive charge

in a physics lab, a student uses a hand-held Van de Graaff generator to attract a neutral, aluminum soda can. What is the correct explanation for the attraction?

electrons are free to move in the conducting aluminum can, so they pile up near the VdG generator if it is positively charged, and on the opposite side if it is negatively charged. The induced “unlike charge” is closer than the induced “like charge”, so there is an attraction.

in electrostatics, the “excess charge” of a charged conductor is found…

only on the surface

in electrostatics, the electric field just outside a conductor is…

perpendicular to the surface

what is an electron-Volt?

a unit of energy

you and some friends decide to go camping in the mountains. Looking over the maps and contemplating the terrain reminds you of the analogy between gravitational and electric forces. In this analogy, the curving contour lines correspond to…

equipotential surfaces

you and some friends decide to go camping in the mountains. Looking over the maps and contemplating the terrain reminds you of the analogy between gravitational and electric forces. In this analogy, the courses of streams and creeks correspond to…

electric field lines

You and some friends decide to go camping in the mountains. Looking over the maps and contemplating the terrain reminds you of the analogy between gravitational and electric forces. In this analogy, the height of the terrain at any given point correspond to…

the value of the electric potential

You and some friends decide to go camping in the mountains. Looking over the maps and contemplating the terrain reminds you of the analogy between gravitational and electric forces. In this analogy, the steepness of the terrain at any given point correspond to…

the magnitude of the electric field

the voltage (electric potential) inside a conductor must…

be a constant everywhere, but not necessarily zero

in electrostatics, the electric field inside a conductor is…

zero

what is resistivity?

material property that depends on

• chemical structure

• temperature

several resistors are combined in series, so the effective resistance is…

larger than the resistance of the largest resistor

several resistors are all combined in parallel, so the resulting effective resistance is…

less than the resistance of the smallest resistor

where does most of an atom’s mass come from?

protons and neutrons — both have about the same mass

“nucleons” is the name for…

protons and neutrons considered as a group

what is the atomic number for symbol 56 (on top) 26 (on bottom) Fe (iron)?

26

what is the atomic mass number for symbol 56 (on top) 26 (on bottom) Fe (iron)?

56

how many protons does an atom of 56 (on top) 26 (on bottom) Fe (iron) have?

26

how many neutrons does an atom of 56 (on top) 26 (on bottom) Fe (iron) have?

30

how many nucleons does an atom of 56 (on top) 26 (on bottom) Fe (iron) have?

56

what are isotopes?

atoms of the same element but with different numbers of neutrons

what is a photon?

the modern name for a discrete packet of energy making up light

in Bohr’s original planetary model of the atom, the electrons…

orbit the nucleus in circles with radii that can only be specific discrete number

what was the main advantage of Bohr’s planetary model?

it explained the existence of spectral lines

in quantum mechanics, everything has…

some particle and some wave properties

what can De Broglie waves be regarded as?

waves of probability

what does a Neon sign not produce?

an absorption spectrum

the sun’s spectrum consists of a bright background crossed by dark lines. what does this suggest?

the sun is a hot object surrounded by a “cool“ atmosphere

what is the difference between adjacent energy levels in the hydrogen atom?

it’s larger for small principal quantum numbers

when is a hydrogen atom said to be in a ground state?

whenever its electron is in the lowest energy level

what is the Pauli Exclusion Principle?

rule that says no two electrons in the same atom can have all their quantum numbers be identical at the same time

what is the atomic mass number of an atom?

how many total neutrons and protons an atom has