Physics Exam 1:

In a region where the electric field is uniform and points in the +x direction, the electric potential is -200V at x=8m and is +400V at x=2. What is the magnitude of the electric field? A. 200 V/m B. 300 V/m C. 400 V/m D. 500 V/m E. 600 V/m

C. 400 V/m

If the length and diameter of a wire of a circular cross section are both tripled, the resistance will be: A.Unchanges B. Tripled. C. Increased by a factor of 8. D. 1/3 of what it originally was. E. 1/9 of what it originally was.

D. 1/3 of what it originally was.

When a dielectric material is introduced between the plates of a parallel-plate capacitor and completely fills the space, the capacitor increases by factor of 4. What is the dielectric constant of the material that was introduced? A. 0.4 B. 1/4 C. 2 D. 4 E. None of the other choices is correct,

D. 4

An ideal parallel plate capacitor has a capacitance of C. If the area of the plates is doubled and the distance between the plates is halved, what is the new capacitance? A. C/4 B. C/2 C. 2C D. 4C

D. 4C

Two stationary point charges q1 and q2 are shown in the figure along with a sketch of some field lines representing the electric field produced by them. What can you deduce from the sketch? A. q1 is negative and q2 is positive; the magnitudes are equal. B. q1 and q2 have the same sign; the magnitudes are equal. C. q1 is positive and q2 is negative; the magnitudes of q1 is greater than the magnitude of q2. D. q1 is negative and q2 is positive; the magnitude of q1 is less than the magnitude of q2. E. q1 and q2 have the same sign; the magnitude of q1 is greater than the magnitude of q2.

D. q1 is negative and q2 is positive; the magnitude of q1 is less than the magnitude of q2.

Four resistors of 20Ω, 40Ω, and 80Ω, are connected in series across an ideal dc voltage source. If the current through this circuit is 0.50 A, what is the voltage of the voltage source? A. 20V B. 40V C. 60V D. 80V E. 100V

E. 100 V

Two charges of opposite sign and equal magnitude Q = 0.82 C are held 2.0m apart shown. Determine the electric potential at point P? A. 1.1E9 V B. 2.2E9 V C. 4.5E9 V D. 9.0E9 V E. Zero volts

E. Zero Volts

T/F: Doubling the capacitance of a capacitor that is holding a constant charge causes the energy stored in that capacitor to double

False

T/F: For AC current the RMS current, Irms is the maximum or peak current

False

T/F: The electron Volt (eV) is a unit of power

False

T/F: The length of a certain wire is kept the same while its radius is doubled. The resistance of this wire does not change.

False

T/F: The strength of the electric field between two oppositely charged parallel plates is not uniform from the positive plate to the negative plate

False

T/F: Two identical bulbs in series will not have the same brightness

False

T/F: Two protons are released from rest, with only the electrostatic force acting, their acceleration will keep increasing

False

T/F: if the resistance in a constant voltage is doubled, the power dissipated by that circuit will increase by a factor of two (2)

False

A charge of 12C passes through an electroplating apparatus in 2.0mins. What is the average current in the apparatus? A. 0.10A B. 0.60A C. 1.0A D. 6.0A

A. 0.10A

Two electrons are 20.0mm apart at closest approach. What is the magnitude of the maximum electric force that they exert on each other? A. 5.8E-25 N B. 2.3E10 N C. 2.3 N D. 5.8E-27 N

A. 5.8E-25 N

Four point charges of equal magnitude but with varying signs are arranged on three of the corners and at the center of the square of side d as shown in the figure. Which one of the arrows shown represents the net force acting on the center charge? A. A B. B C. C D. D

A. A

Which one of the arrows shown in the figure best represents the direction of the electric field between the two uniformly charged metal plates? A. A B. B C. C D. None of the above

A. A

Four unequal resistors are connected in a parallel with each other. Which one of the following statements is correct about this combination? A. The equivalent is less than of that of the smallest resistor. B. The equivalent resistance is equal to the average of the four resistors. C. The equivalent resistance is midway between the largest and smallest resistance. D. The equivalent is more than the largest resistance. E. None of the other choices is correct.

A. The equivalent is less than of that of the smallest resistor.

T/F: A Hydrogen nucleus, which has a charge +e, is situated to the left of a carbon nucleus , which has a charge of +6e. Is it true that the electrical force experienced by the hydrogen nucleus is to the left, and the magnitude is equal to the force exerted on the carbon nucleus.

True

T/F: A dialetric material such as paper is inserted between the plates of a capacitor as the capacitor holds a fixed charge on its plates. The electric field between the plates as the dielectric is inserted will become weaker

True

T/F: Electrically neutral objects cannot exert electrical force on each other

True

T/F: Suppose you have two capacitors and want to use them to store the maximum amount of energy by conducting them across a voltage source. You should connect them in parallel across the source

True

T/F: The amount of current in a circuit depends jointly on the battery emf and the resistance of the circuit attached to the battery

True

T/F: The fundamental charge (e) is the magnitude of the charge of an electron or proton: e= 1.60 x10-19C.

True

If the maximum voltage of an AC signal is 8.0 V, what is the rms value of this voltage? A. 2.8V B. 5.7V C. 6.2V D. 4.0V E. 16.0V

B. 5.7V

T/F: The resistivity of a material increases as the temperature goes up

True

The plates of a parallel plate capacitor are maintained with constant voltage by a battery as they are pulled apart. What happens to the strength of the electric field between the plates during this process? A. It increases. B. It decreases. C. It remains constant. D. It cannot be determined from the information given.

B. It decreases

Kirchhoff's junction rule is a statement of: A. The law of conservation of momentum. B. The law of conservation of charge. C. The law of conservation of energy. D. The law of conservation of angular momentum. E. Newton's second law.

B. The law of conservation of charge.