PHYS 202 Final Exam

There are three types of charge: positive, negative and neutral

False

When an object becomes charged, it is normally due to a transfer of positive charges.

False

An electron and a proton have different magnitudes of charge.

False

In a conducting material some electrons are loosely bound to their atoms and can move freely within the material.

True

Electric charge can be created or destroyed depending on the process.

False

The nucleus of an atom has a net positive charge.

True

Charging an object by conduction will produce the same type charge on the charged object as the charging object.

True

When the needle of an electroscope deflects, we can conclude it is negatively charged.

False

Grounding occurs when an object is connected to the earth by a conductor.

True

If a glass rod is charged positively by rubbing with silk, the silk will also be charged positively.

False

If a positively charged rod is brought near, but does not touch, the end of an isolated neutral rod, a negative charge will be induced on this end of the neutral rod, but the rod will remain neutral.

True

An atomic nucleus has a charge of +40e. What is the magnitude of the electric field at a distance of 1m from the nucleus?

5.8 * 10^-8 N/C

Is it possible to have a zero electric field value between two positive charges along the line joining the two charges?

Yes, regardless of the magnitude of the two charges.

If the electric field between the plates of a given capacitor is weakened, the capacitance of that capacitor

does not change

A uniform electric field, with a magnitude of 500 V/m, points in the +x direction. If the electric potential at x=5m is 2500 V, what is the potential at x=2m?

4000V

It takes 20J of energy to move 5.0C of charge from point A to B. What is the potential difference between points A and B?

4.0V

Sphere A carries a net positive charge, and sphere B is neutral. They are placed near each other on an insulated table. Sphere B is briefly touched with a wire that is grounded. Which statement is correct?

Sphere B is now negatively charged.

Two charged objects are separated by a distance d. The first charge is larger in magnitude than the second charge.

The charges exert forces on each other equal in magnitude and opposite in direction.

The absolute potential at the center of a square is 3.0V when a charge of +Q is located at one of the square's corners. What is the absolute potential at the square's center when a second charge of -Q is placed at one of the remaining corners?

zero

Two charges are separated by a distance d and exert mutual forces of F on each other. If the charges are separated by a distance of 3d, what are the new mutual forces?

F/9

A solid block of mental in electrostatic equilibrium is placed in a uniform electric field. Give a statement concerning the electric field in the block's interior.

There is no electric field in the block's interior.

One coulomb per volt is a

farad

A surface on which all points are at the same potential is referred to as

an equipotential surface

Conventional current (I) is assumed to be the flow of positive charge

True

Batteries create or supply charge

False

Potential (or voltage) "flow" through the circuit.

False

Conventional current goes from points of higher potential (higher voltage) to points of lower potential.

True

Charge loses potential energy going through a resistor, so there is a drop in the potential across the resistor when crossing the resistor in the direction of current (or in the assumed direction of current).

True

We usually assume that the wires in a circuit have resistance of zero, thus any two points in a circuit connected by a wire are at the same potential.

True

Resistors in parallel always have the same current through them.

False

Conservation of energy implies that the sum of the voltage rises and drops in complete trip around a closed circuit loop must be zero.

True

Two 20pF and one 10pF capacitors are connected in series. The equivalent capacitance is:

5.00pF

A 5.0uF, and a 13uF and a 30uF capacitor are connected in parallel. How much capacitance would a single capacitor need to have to replace the three capacitors?

48 uF

At a particular instant, an electron moves to at the right at speed v in a uniform magnetic field that is directed straight downward. The magnetic force that acts on it is

directed out of the page

Consider two copper wires. One has twice the length of the other. How do the resistances of these two wires compare?

The longer wire has twice the resistance of the shorter wire.

As more and more capacitors are connected in parallel, the equivalent capacitance of the combination increases.

Always true

Kirchhoff's junction rule is an example of

conservation of charge

A charged particle is injected into a uniform magnetic field such that its velocity vector is perpendicular to the magnetic field vectors. Ignoring a particle will

follow a circular path

A galvanometer can be converted to a voltmeter by the addition of a

large resistance in series

If the current flowing through a circuit of constant resistance is doubled, the power is dissipated by that circuit will

quadruple

P=I^2 R

A charged particle moves and experiences no magnetic force. From this we can conclude that

either no magnetic field exists or the particle is moving parallel to the field.

Two long parallel wires placed side-by-side on a horizontal table carry identical size currents in opposite directions. The wire on your right carries current toward you, and the wire on your left carries current away from you. From your point of view, the magnetic field at the point exactly midway between the two wires

points down

A 9 Volt battery is hooked up to two resistors in series. One has a resistance of 5 Ohms, and the other has a resistance of 10 Ohms. Several locations along the circuit are marked with letters, as shown....

The current A is equal to the current B, which is equal to the current at C, which is equal to the current D

The south pole of a magnet point towards the Earth's

South Pole

The primary coil of an ideal transformer has 200 turns and its secondary has 100 turns. If the input voltage to the primary is 100 V, we can expect the output voltage of the secondary to be

50V

At the second maxima on either side of the central bright spot in a double-slit experiment, light from

one opening travels two wavelengths of light farther than light from the other opening

For all transparent material substances, the index of refraction

is greater than 1

According to Lenz's law, the direction of an induced current in a conductor will be that which tends to produce which of the following effects?

oppose the effect which produces it

In the figure above, a coil of wire is placed on the axis of a solenoid carrying a DC current. Which of the following will NOT result in a EMF being induced in the coil?

Rotate the coil about the z-axis

In an electromagnetic wave in free space, the electric and magnetic field are

perpendicular to one another and perpendicular to the direction of wave propagation

An object is placed at a concave mirror's center of curvature. The image produced by the mirror is located

at the center of curvature

If a single lens forms a virtual image of an object, then

The lens could be either diverging or converging lens

The colors on an oil slick are caused by reflection and

interference

The critical angle for a beam of light passing from water into air is 48.8 degrees. This means that all light rays with an angle of incidence less than this angle will be

partially reflected and partially transmitted

A circular coil lies flat on a horizontal surface. A bar magnet is held fixed above the center of the coil with its north pole pointing downward. What is the direction of the induced current in the coil, as viewed from above?

There is no current in the coil

A single convex spherical mirror produces an image which is

always virtual

A radioactive sample has a half-life of 5 min. What fraction of the sample is left after 15 min?

1/8

When a B+ particle is emitted from an unstable nucleus, the atomic number of the nucleus, Z,

decreases by 1

Why do heavy nuclei contain more neutrons than protons?

Neutrons counter act the electric repulsion of the protons

If an atom's atomic number is given by Z, its atomic mass number by A, and its neutron number by N, which of the following is correct?

N=A-Z

In beta minus decay

an electron is emitted

Atoms with the same atomic number but with different numbers of neutrons are referred to as

isotopes

Which of the following statements concerning the nuclear force is false?

The nuclear force is very weak and much smaller in relative magnitude than the electrostatic and gravitational forces.

What happens to the half-life of a radioactive substance as it decays?

It remains constant

A gamma ray is also known as

a photon

In all three types of radioactive decay, what value is conserved in addition to electric charge, energy, and momentum?

nucleon number

The mass of an atom is

concentrated in the nucleus