Test One Conceptual Questions
(c) the charge on the capacitor had increased
An air-filled parallel-plate capacitor is connected to a battery and allowed to charge up. Now a slab of dielectric material is placed between the plates of the capacitor while the capacitor is still connected to the battery. After this is done, we find that A) the energy stored in the capacitor had decreased. B) the voltage across the capacitor had increased. C) the charge on the capacitor had increased. D) the charge on the capacitor had not changed. E) None of these choices are true. (practice exam 4)
(a) conductor
An electric...................allows charge to easily move through it. a) Conductor b) Insulator c) Semi-Conductor (practice exam one)
(a) neutral
An object is said to be.................if all positive charges in the object are balanced by a negative charge, leaving no net charge. a) Neutral b) Positively charged c) Negatively charged (practice exam one)
(b) conduction
Applying a charge by touching a charged object to a neutral object is.................. a) Induction b) conduction (practice exam one)
(b) conduction
Separating the charges in an object without touching it is called................ a) Induction b) Conduction (practice exam one)
(b) dipole
The combination of two separated point charges of opposite sign but equal magnitude is called an electric: a. monopole. b. dipole. c. quadrupole. d. magnapole. (practice exam 2)
(d) perpendicular outward and away from the charge
The electric field at the surface of a positively charged conductor has a direction characterized by which of the following? a. tangent to the surface b. perpendicular inward toward the charge c. at a 45 degree angle to the surface d. perpendicular outward and away from the charge (practice exam 2)
(a) twice as strong as the field of one charge alone and points toward the negative charge
The electric field midway between equal positive and negative charges is. . . (a) twice as strong as the field of one charge alone and points toward the negative charge (b) twice as strong as the field of one charge alone and points toward the positive charge (c) is zero (practice exam 2)
(c) electric field acting on the test charge
The electric force acting on a test charge (q) at a point divided by the value of the charge is the: (a) acceleration of the charge (b) electric field created by the test charge (c) electric field acting on the test charge (d) the energy of the test charge (practice exam 2)
(a) zero everywhere
The static electric field inside an object made from a conducting material is. . . (a) zero everywhere (b) constant in magnitude only (c) constant in magnitude and direction, but not necessarily zero (d) greater than the electric field outside (practice exam 2)
True
True or False? A coulomb of charge corresponds to 6.24 X 1018 elementary charges of size e= 1.602 X10-19C? (practice exam one)
True
True or False? A negative ion is an atom that has gained electrons? (practice exam one)
False
True or False? A positive ion is an atom that has gained protons? (practice exam one)
true
True or False? A region of uniform electric field has parallel field lines. (practice exam 2)
False
True or False? As current flows through a uniform wire, the wire gets hotter because the electrons stop moving and therefore transform their lost kinetic energy into thermal energy in the wire. (practice exam 4)
true
True or False? Electric field lines point towards negative charges and away from positive charges (practice exam 3)
false
True or False? Electric field lines point towards positive charges and away from negative charges. (practice exam 2)
False
True or False? In a conductor like copper metal, all of its electrons are free to move (practice exam 3)
False
True or False? In a vertically upward electric field, the electric potential increases with height (practice exam 2)
true
True or False? Insulators are materials that lack free charges (practice exam 2)
False
True or False? Net charge of a conductor distributes itself throughout the volume of the object (practice exam 3)
false
True or False? The electric force on an electrically neutral object is always zero (practice exam 2)
True
True or False? The equipotentials between oppositely charged parallel plates are planes (practice exam 2)
False
True or False? The net charge of a piece of metal is the same as its free charge (practice exam 3)
False
True or False? a 2uF and 4uF capacitor in a series have equal voltages between their plates (practice exam 3)
False
True or False? a Van de Graaff generator cannot attract neutral objects (practice exam 3)
false
True or False? a region with parallel electric field lines has a constant electric potential (practice exam 3)
false
True or False? electric field lines close together indicate weak electric field strength (practice exam 3)
true
True or False? good conductors are materials that have a lot of free charges (practice exam 2)
false
True or False? the electric field inside a conductor carrying a current is zero (practice exam 3)
True
True or false? An insulator is a material that is lacking in free charge? (practice exam 2)
False
True or false? Net charge of a conductor distributes itself throughout the volume of the object (practice exam 2)
False
True or false? The electric potential increases as you move in the direction of the electric field (practice exam 2)
false
True or false? The electron-volt is a unit of electron potential (practice exam 2)
False
True or false? The region with parallel electric field lines has a constant electric potential (practice exam 2)
True
True or false? When oppositely charged objects are moved apart, their electric potential energy increases (practice exam 2)
True
True or false? Where electric field lines are crowded together, the electric field strength is high (practice exam 2)
False
True or false? a Van de Graaff generator cannot attract neutral objects (practice exam 2)
True
True or false? electric field strength is largest near the sharp points of a charged conductor (practice exam 2)
False
True or false? in a conductor like copper metal, all of its electrons are free to move (practice exam 2)
False
True or false? the net charge of a piece of metal is the same as its free charge (practice exam 2)
(a) in series
Two capacitors are identical. They can be connected in series or in parallel. If you want the smallest equivalent capacitance for the combination, how should you connect them? a) in series b) in parallel c) either way because both combinations have the same capacitance (practice exam 3)
(a) the charge on C2 increases
Two capacitors, C1 and C2, are connected in series across a source of potential difference. With the potential source still connected, a dielectric is now inserted between the plates of capacitor C1. What happens to the charge on capacitor C2? A) The charge on C2 increases. B) The charge on C2 decreases. C) The charge on C2 remains the same. (practice exam 4)
(c) 1/4F
Two identical small charged spheres are a certain distance apart, and each one initially experiences an electrostatic force of magnitude F due to the other. With time, charge gradually leaks off of both spheres. When each of the spheres has lost half its initial charge, the magnitude of the electrostatic force will be (a) 1/16F (b) 1/8F (c) 1/4F (d) 1/2F (practice exam one)
(a) electrons were added to the object
Two lab partners are doing a static electricity investigation. They begin with a neutral pop can. After conducting the procedure, they observe that the pop can has become charged negatively.Which statement accurately explains how this happened? a. Electrons were added to the object. b. Protons were added to the object. c. Electrons were removed from the object. d. Protons were removed from the object. (practice exam one)
(a) towards the negative plate
Two parallel metal plates are separated by 5cm and given equal and opposite charges, producing a nearly uniform electric field of strength E = 250 N/C between them. The electric field caused by the charged plates points . . . (a) parallel to the plates (b) towards the positive plate (c) towards the negative plate (practice exam 3)
I, III, IV
Which statements are true for an electron moving in the direction of an electric field? (There may be more than one correct choice.) I. Its electric potential energy increases as it goes from high to low potential. II. Its electric potential energy decreases as it goes from high to low potential. III. Its potential energy increases as its kinetic energy decreases. IV. Its kinetic energy decreases as it moves in the direction of the electric field. V. Its kinetic energy increases as it moves in the direction of the electric field. (practice exam 4)
I-III-IV
Which statements are true? I. If positive charge moves direction of E, field does positive work on charge II. If negative charge moves direction of E, field does positive work on charge III. If negative charge moves opposite direction of E, field does positive work on charge. IV. Positive charge moves opposite to E, potential energy decreases (practice exam 2)
(d) X is negative and Y is positive
X and Y are two uncharged metal spheres on insulating stands, and are in contact with each. other. A positively charged rod R is brought close to X. Sphere Y is now moved away from X. What are the final charges of X and Y? A) Both X and Y are neutral. B) X is positive and Y is neutral. C) X is neutral and Y is positive. D) X is negative and Y is positive. E) Both X and Y are negative. (practice exam one)
thermal energy
a battery is connected to a resistor. As charge flows, the chemical energy of the battery is dissipated as . . . (practice exam 4)
(b) decrease the current in the circuit
a battery is connected to a resistor. Increasing the resistance of the resistor will. . . (a) increase the current in the circuit (b) decrease the current in the circuit (c) not affect the current in the circuit (practice exam 4)
electrons
the charge carriers in metals are. . . (practice exam 4)
(b) the resistance of a wire is directly proportional to the length of the wire
Which one of the following is the correct statement regarding the resistance? A) The resistance of a conductor decreases with temperature. B) The resistance of a wire is directly proportional to the length of the wire. C) None of the above statements is correct. D) All of the above statements are correct. (practice exam 4)
(b) The charge of an electron is negative, while the charge of a proton is positive. They both have the same magnitude, 1.6 × 10-19C
How does the charge of an electron differ from the charge of a proton? How are they similar? a) The charge of an electron is positive, while the charge of a proton is negative. They both have the same magnitude, 1.6 × 10-19C b) The charge of an electron is negative, while the charge of a proton is positive. They both have the same magnitude, 1.6 × 10-19C (practice exam one)
(c) must have a negative net charge
If a positively charged plastic rod repels an object, that other object a. must have a net positive charge. b. must have no net charge. c. must have a negative net charge. d. must have a net charge induced by the rod. (practice exam one)
(a) increases
In a certain region of space, a uniform electric field is in the x direction. A particle with negative charge is carried from x = 20.0 cm to x = 60.0 cm. The electric potential energy of the charge-field system: a) increases. b) remains constant. c) decreases. d) changes unpredictably. (practice exam 3)
(d) increasing the gap between the charged plates
In a parallel-plate capacitor; how can the capacitance be decreased? (a) increasing the stored charge in the capacitor (b) decreasing the stored charge in the capacitor (c) decreasing the gap between the charged plates (d) increasing the gap between the charged plates (practice exam 3)
(e) 4F
When two equal but opposite charges q1= −q2 are separated by 1.00 cm, they exert a Coulomb force of magnitude F on each other. If each charge is doubled in magnitude, the force becomes a) F/4 b) F/2 c) F d) 2F e) 4F (practice exam one)
(a) the potential difference across each capacitor is the same
When two or more capacitors are connected in parallel across a potential difference A) the potential difference across each capacitor is the same. B) each capacitor carries the same amount of charge. C) the equivalent capacitance of the combination is less than the capacitance of any of the capacitors. D) All of the above choices are correct. E) None of the above choices are correct. (practice exam 4)
(D) all of the above choices are correct
When two or more capacitors are connected in series across a potential difference, A) the potential difference across the combination is the algebraic sum of the potential differences across the individual capacitors. B) each capacitor carries the same amount of charge. C) the equivalent capacitance of the combination is less than the capacitance of any of the capacitors. D) All of the above choices are correct. E) None of the above choices are correct. (practice exam 4)
(c) the rod gains electrons and the fur loses electrons
When you rub a plastic rod with fur, the plastic rod becomes negatively charged and the fur becomes positively charged. As a consequence of rubbing the rod with the fur, A. the rod and fur both gain electrons B. the rod and fur both lose electrons C. the rod gains electrons and the fur loses electrons D. the rod loses mass and the fur gains mass. E none of the above. (practice exam one)
(a) equipotential are perpendicular to the electric field vector
Which of the following is false? (a) equipotential are perpendicular to the electric field vector (b) the surface of a conductor is an equipotential surface (c) the electric field vector points towards higher potential (d) the electric field inside a conductor in electrostatic equilibrium is zero (practice exam 3)
the electron
A proton and an electron are placed in an electric field. Which undergoes the greater acceleration? (practice exam 4)
(b) 100eV
A proton is moved through a potential difference of 100 volts in an electric field. How much work in electron-volts was required to move this charge? a. 10eV b. 100eV c. 10J d. 100V (practice exam 2)
1 and 2
Which of these statements are right? 1. Good conductors are materials that have a lot of free charges. 2. Insulators are materials that lack free charges. 3. The electric force on an electrically neutral object is always zero. (practice exam one)
(b) it has zero net charge
A tiny styrofoam ball is suspended on a thread. Tests show it gets attracted to a positively charged rod, and also attracted by a negatively charged rod. What can you can conclude about the tiny styrofoam ball? a. It has a negative net charge b. It has zero net charge. c. It has positive net charge. d. Its net charge changes when then rods are placed near it. (practice exam one)
(a) negative
A balloon acquires a positive charge when rubbed on a sweater. As a result, the charge acquired by the sweater is (a) negative (b) zero (c) positive (practice exam 2)
(c) potential difference
A capacitor remains connected to a battery while each of its plates are moved further apart. Which of these quantities remains unchanged? (a) charge (b) capacitance (c) potential difference (d) electric field (practice exam 3)
(d) the capacitance remains the same, and the charge doubles
A capacitor stores charge Q at a potential difference DV. What happens if the voltage applied to the capacitor by a battery is doubled to 2 DV? a) The capacitance falls to half its initial value, and the charge remains the same. b) The capacitance and the charge both fall to half their initial values. c) The capacitance and the charge both double. d) The capacitance remains the same, and the charge doubles. (practice exam 3)
(b) from low potential to high potential
A negative charge, if free, will tend to move A) from high potential to low potential. B) from low potential to high potential. C) toward infinity. D) away from infinity. E) in the direction of the electric field. (practice exam 4)
(b) the electric force between charged particles decreases with increasing distance.
A positively charged piece of plastic exerts an attractive force on an electrically neutral piece of paper. This is because A. electrons are less massive than atomic nuclei. B. the electric force between charged particles decreases with increasing distance. C. an atomic nucleus occupies only a small part of the volume of an atom. D. a typical atom has many electrons but only one nucleus. E. plastic and paper have different densities. (practice exam one)
loosely bound
Charge carriers in a metal are electrons rather than protons because electrons are. . . (practice exam 4)
(a) inversely proportional
Coulomb's Law states that the magnitude of the force between two charges is _______ to the square of the distance between them. a) inversely proportional b) proportional (practice exam one)
(a) true
Electrostatics is the study of electric charges that are not moving. a) True b) False (practice exam one)
(b) coulomb
What is the SI unit of charge? a) Newton b) Coulomb c) Watt (practice exam one)
(E) at none of the above speeds
When electric current is flowing in a metal, the electrons are moving A) at nearly the speed of light. B) at the speed of light. C) at the speed of sound in the metal. D) at the speed of sound in air. E) at none of the above speeds. (practice exam 4)
quadrouples
When the distance between two charges is halved, the electrical force between the charges (practice exam 4)
(a) 1/4
When the separation between two-point charges is doubled, the electric force acting between them changes by a factor of (a) 1/4 (b) 1/2 (c) 1 - no change (d) 2 (e) 4 (practice exam 2)
(b) 1/2
When the separation between two-point charges is doubled, their electric potential energy changes by a factor of (a) 1/4 (b) 1/2 (c) 1 - no change (d) 2 (e) 4 (practice exam 2)
