When charged particles move through a conductor such as copper wire, what moves? conduction electrons conduction neutrons conduction protons
Which of these particles has the smallest amount of positive charge? proton neutron electron
Which can be produced in a pair production? two protons an electron and a positron an electron and a proton two electrons two neutrons
A positively charged metal sphere A is brought into contact with an uncharged metal sphere B. As a result: both spheres are positively charged A is positively charged and B is neutral A is positively charged and B is negatively charged A is neutral and B is positively charged A is neutral and B is negatively charged
If excess charge is put on a spherical nonconductor, it spreads a little from where it was placed but not over the whole sphere it remains where it was placed it spreads uniformly throughout the volume of the conductor it spreads uniformly over the surface of the sphere if the sphere is small it spreads uniformly over the surface of the sphere
In defining an electric field, a test charge is used. Is the test charge positively or negatively charged? Which describes the direction of the electric field vector? Negatively charged. The field vector is in the same direction as the force on the test charge. Negatively charged. The field is in the opposite direction from the force on the test charge. Positively charged. The field vector is in the same direction as the force on the test charge. Positively charged. The field is in the opposite direction from the force on the test charge.
What is the direction of the electric field vectors set up by a positively charged particle? perpendicular to a radial line extending from the particle radially toward the particle radially away from the particle
Which describes the direction of the dipole moment vector for an electric dipole? It points from the positive charge to the negative charge. It is along the perpendicular bisector of the line connecting the two charges. It points from the negative charge to the positive charge.
Which describes a volume charge density? the charge per unit length the charge per unit area the charge per unit volume the length per unit charge the area per unit charge the volume per unit charge
Which describes the electric field on the central axis through a disk of uniform positive charge? The field vectors point along the axis and toward the disk on both sides of the disk. The field vectors point along the axis and away from the disk on both sides of the disk. The field vectors point along the axis and away from the disk on one side of the disk and toward the disk on the opposite side.
A small object has charge Q > 0. Charge q(0 ≤ q ≤ Q) is removed from it and placed on a second small object. The two objects are placed 1 m apart. For the force that each object exerts on the other to be a maximum, q should be: 3Q/4 Q Q/2 Q/4 0
A 5.0-C charge is 10 m from a -2.0-C charge. The electrostatic force is on the positive charge is: 9.0×108 N toward the negative charge 9.0×108 N away from the negative charge 9.0×109 N toward the negative charge 9.0×109 N away from the negative charge none of these
In the Rutherford model of the hydrogen atom, a proton (mass M, charge Q) is the nucleus and an electron (mass m, charge q) moves around the proton in a circle of radius r. Let k denote the Coulomb force constant (1 /4πε0) and G the universal gravitational constant. The ratio of the electrostatic force to the gravitational force between electron and proton is: kMm/GQq kQq/GMmr2 GMm/kQq kQq/GMm GQq/kMm
Particle 1 with charge q1, and particle 2, with a charge q2, are on the x axis, with particle 1 at x = a with and particle 2 at x = −2a. For the net force on a third charged particle, at the origin to be zero q1 and q2 must be related by q2=: 2q1 4q1 −2q1 −4q1 −q1/4
A charge Q is spread uniformly along the circumference of a circle of radius R. A point particle with charge q is placed at the center of this circle. The total force exerted on the particle q can be calculated by Coulomb's law: if you use R for the distance if you use 2R for the distance if you use 2πR for the distance and the result of the calculation is zero none of the above
Two identical conducting spheres A and B carry equal charge and exert electrostatic forces of magnitude F on each other. They are separated by a distance much larger than their diameters. A third identical conducting sphere C is uncharged. Sphere C is first touched to A, then to B, and finally removed. As a result, the electrostatic force between A and B becomes: F/2 F/4 3F/8 F/16 0
The electric field at a distance of 10 cm from an isolated point particle with a charge of 2×10−9 C is: 1.8 N/C 18 N/C 180 N/C 1800 N/C none of these
An isolated charged point particle produces an electric field with magnitude E at a point 2 m away. At a point 1 m from the particle the magnitude of the field is: E 2 E 4 E E/2 E/4
Two point particles, with charges of q1 and q2, are placed a distance r apart. The electric field is zero at a point P between the particles on the line segment connecting them. We conclude that: q1 and q2 must have the same magnitude and sign P must be midway between the particles q1 and q2 must have equal magnitudes and opposite signs q1 and q2 must have opposite signs and may have different magnitudes q1 and q2 must have the same sign but may have different magnitudes
Two point particles, one with charge +8×10−9 C and the other with charge −2×10−9 C, are separated by 4 m. The electric field midway between them is: 22.5 N/C 9×109 N/C 36×10−9 N/C 13,500 N/C 135,000 N/C
A uniform electric field of 300 N/C makes an angle of 25∘ with the dipole moment of an electric dipole. If the torque exerted by the field has a magnitude of 2.5×10−7 N⋅m, the dipole moment must be: 8.3×10−10 C⋅m 9.2×10−10 C⋅m 2.0×10−9 C⋅m 8.3×10−5 C⋅m 1.8×10−4 C⋅m
The dipole moment of a dipole in a 300-N/C electric field is initially perpendicular to the field, but it rotates so it is in the same direction as the field. If the moment has a magnitude of 2×10−9 C⋅m the work done by the field is: −12×10−7 J −6×10−7 J 0 J 6×10−7 J 12×10−7 J
A disk has a hole in its center. The outer radius of the disk is 4.25 cm and the inner radius is 2.65 cm. A charge of +6.95 nC is spread uniformly over the disk. What is the magnitude of the electric field strength (N/C) 8.50 cm from the center of the disk along a line perpendicular to its center? 3.78×103 6.19×104 5.24×103 6.82×103 3.41×104 1.37×104 4.17×103 9.62×103 4.26×103 7.12×104
Earth's atmosphere is constantly bombarded by cosmic ray protons that originate somewhere in space. If the protons all passed through the atmosphere, each square meter of Earth's surface would intercept protons at the average rate of 2000 protons per second. What would be the electric current in amperes intercepted by a 15×107 km2 area on the planet? Number Units
Two particles are fixed on an x axis. Particle 1 of charge 40.8 μC is located at x = −11.1 cm; particle 2 of charge Q is located at x = 11.2 cm. Particle 3 of charge magnitude 42.8 μC is released from rest on the y axis at y = 11.1 cm. What is the value of Q if the initial acceleration of particle 3 is in the positive direction of (a) the x axis and (b) the y axis? (a) Number Units (b) Number Units
We know that the magnitudes of the negative charge on the electron and the positive charge on the proton are equal. Suppose, however, that these magnitudes differ from each other by 0.00032%. With what force would two copper coins, placed 1.2 m apart, repel each other? Assume that each coin contains 2.5×1022 copper atoms. (Hint: A neutral copper atom contains 29 protons and 29 electrons.) Number Units
Two charged beads are on the plastic ring in Figure (a). Bead 2, which is not shown, is fixed in place on the ring, which has radius R = 62.9 cm. Bead 1 is initially on the x axis at angle θ = 0∘. It is then moved to the opposite side, at angle θ = 180∘, through the first and second quadrants of the xy coordinate system. Figure (b) gives the x component of the net electric field produced at the origin by the two beads as a function of θ, and Figure (c) below gives the y component. The vertical axis scales are set by Exs = 5.70× 104 N/C and Eys = −10.26×104 N/C. (a) At what positive angle θ is bead 2 located? (Note: bead 2 is negative charged). What are the charges of (b) bead 1 and (c) bead 2? (a) (b) (c)
Part (a) of the figure shows two charged particles fixed in place on an x axis with separation L. The ratio q1/q2 of their charge magnitudes is 4.00. Part (b) of the figure shows the x component Enet,x of their net electric field along the x axis just to the right of particle 2. The x axis scale is set by xs = 30.3 cm. (a) At what value of x > 0 is Enet , x maximum? (b) If particle 2 has charge −3e, what is the value of that maximum? Assume e = 1.602×10−19 C. (a) (a) Number (b) Number (b)
In the figure a nonconducting rod of length L = 8.44 cm has charge −q = −4.50 fC uniformly distributed along its length. (a) What is the linear charge density of the rod? What are the (b) magnitude and (c) direction (positive angle relative to the positive direction of the x axis) of the electric field produced at point P, at distance a = 14.9 cm from the rod? What is the electric field magnitude produced at distance a = 65 m by (d) the rod and (e) a particle of charge −q = −4.50 fC that replaces the rod?
Two small charged objects repel each other with a force F when separated by a distance d. If the charge on each object is reduced to one-fourth of its original value and the distance between them is reduced to d/2 the force becomes: F/16 F/8 F/4 F/2 F
In the figure a "semi-infinite" nonconducting rod (that is, infinite in one direction only) has uniform linear charge density λ = 4.50 μC/m. Find (including sign) (a) the component of electric field parallel to the rod and (b) the component perpendicular to the rod at point P(R = 45.4 m). (a) Number 3 Units (b) Number Units
A total charge of 6.3×10−8 C is distributed uniformly throughout a 2.7−cm radius sphere. The volume charge density is 6.9×10−6 C/m2 3.7×10−7 C/m3 7.6×10−4 C/m3 6.9×10−6 C/m3 2.5×10−4 C/m3
Experimenter A uses a test charge 3q0 and experimenter B uses a test charge 5q0 to measure an electric field produced by stationary charges. A finds a field that is the same as the field found by B. either greater or less than the field found by B, depending on the masses of the test charges. either greater or less than the field found by B, depending on the accelerations of the test charges. less than the field found by B. greater than the field found by B.
As used in the definition of electric field, a "test charge" None of the choices are correct. must be a proton must be an electron has zero charge has charge of magnitude 1.6×10−19 C
Negative charge −q is uniformly distributed on the upper half of a rod and positive charge +q is uniformly distributed on the lower half. What is the direction of the electric field at point P, on the perpendicular bisector of the rod?
Two identical conducting spheres are touched together and separated to a distance of 0.0010 m. Before touching, Qa = 2.0 C and Qb = −4.0 C. What is the magnitude of the net force on sphere A? 0 N 3.6E 16 N 7.2E16 N 9.0E15 N
Two conducting spheres have charges of Qa = +1 C and Qb = +1 C. They are touched together and then separated. Afterward, you measure the electrostatic force between them. You repeat the experiment, but this time you double the initial charge of both particles. The second experiment reveals that the electrostatic force has doubled. has quadrupled. has decreased. is unchanged.
In the Millikan Oil Drop experiment, Robert Millikan and Harvey Fletcher determined the elementary electric charge. By dropping a negatively charged oil drop through an electric field, they balanced the downwards force of gravity with an upwards electric force. You conduct a similar experiment by levitating a negatively charged oil drop. If the electrostatic force is 1.96E−30, what is the mass of the particle in kg? kg
0.200 coulombs of charge pass a point in a wire in 5.00 seconds. The current in Amps is: A
The electric field along the axis of a ring-shaped charge of total charge q distributed uniformly is given by E = qz 4πε0(z2 + R2)3/2, where R is the radius of the ring and z is the distance from the center of the ring. The electric field at the center of the ring is zero and at great distances from the ring approaches zero. At a certain distance along the z-axis the electric field strength is maximum. What is the electric field strength at this point?
The figure shows two unequal point charges of opposite sign, Q and q. Charge q has a smaller magnitude than charge Q. In which of the regions, A, B, or C, will there be a point at which the net electric field due to these two charges is zero? All three regions. Only region B. Only region C. Only regions A and C. Only region A.
Two conducting spheres have charges of Qa = 1C and Qb = −1C. They are touched together and then separated. Afterward, you measure the electrostatic force between them. You repeat the experiment, but this time you double the initial charge of both particles. The second experiment reveals that the electrostatic force has doubled. has decreased. is unchanged. has quadrupled.
Indicate which of the following statements concerning the electric field lines is true. Electric field lines point inward toward negative charges. Electric field lines make circles around negative charges. Electric field lines make circles around positive charges. Electric field lines may cross each other in the region between two point charges.
Two conducting spheres have charges of Qa = +3C and Qb = +1 C. They are touched together and then separated. Afterward, you measure the electrostatic force between them. You repeat the experiment, but this time you double the initial charge of both particles. The second experiment reveals that the electrostatic force is unchanged. has quadrupled. has doubled. has decreased.
Three charges are placed in a line. Charge A is at x = −0.0500 m, Charge B is at the origin, and Charge C is at x = 0.0800 m. Based on the charges given below, what is the magnitude of the net force on Charge B in newtons? Qa = 2.00×10−5 C, Qb = 4.00×10−5 C, Qc = 3.00×10−5 C N
The figure shows the velocity of an object for 0 ≤ t ≤ 24. Calculate the following estimates of the distance the object travels between t = 0 and t = 24, and indicate whether each result is an upper or lower estimate of the distance traveled. (a) A left sum with n = 2 subdivisions NOTE: Enter units that match those on the graph. The distance traveled is estimated to be This is (b) A right sum with n = 2 subdivisions. NOTE: Enter units that match those on the graph. The distance traveled is estimated to be This is
Here's a graph of the velocity (in ft/sec) of an object moving along a horizontal line. (a) Over the interval 0 ≤ t ≤ 24, determine the intervals when the object is speeding up and the intervals when the object is slowing down. (b) From the end of Section 5.1 of the textbook, distance traveled is the area under the velocity vs. time graph. Use this to compute the distance traveled by the object from t = 0 to t = 8 seconds, in feet. (c) Compute the distance traveled by the object from t = 8 to t = 20 seconds, in feet.
The maker of an automobile advertises that it takes 15 seconds to accelerate from 15 kilometers per hour to 80 kilometers per hour. Assuming constant acceleration, compute the following. (a) The acceleration in meters per second per second (Round your answer to three decimal places.) m/sec2 (b) The distance the car travels during the 15 seconds (Round your answer to two decimal places.) m