# Physics 245 MC exam1

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### Electric field lines a. circle clockwise around positive charges b. circle counter-clockwise around positive charges c. radiate outward from negative charges d. radiate outward from positive charges

d. radiate outward from positive charges

### At twice the distance from a point charge, the strength of the electric field a. is four times its original value b. is twice its original value c. is one half its original value d. is one fourth its original value e. cant answer without knowing the charge

d. is one fourth its original value

### Two electrically neutral materials are rubbed together. One acquires a net negative charge. The other must a. have lots of electrons b. have gained electrons c. have lost electrons d. have gained protons

c. have lost electrons

d. R is quarted

...

b. J/C

### A proton and electron are in a constant electric field created by oppositely charged plates. You release the proton form the positive side and the electron from the negative side. When it strikes the opposite side which one has more kinetic energy? a. proton b. electron c. both acquire the same kinetic energy d. neither- there is no change of kinetic energy e. they both acquire the same kinetic energy but with opposite signs

c. both acquire the same kinetic energy

b. electron

### Two point charges are separated by 10 meter. If the distance between them is reduced to 5.0 meters, the magnitude of the electrostatic force exerted on each: a. decreases to half its original value b. increases to twice its original value c. decreases to one quarter of its original value d. increases to four times its original value

d. increases to four times its original value

b. R is halved

### Two electrically neutral materials are rubbed together. One acquires a net negative charge, the other must.. a. have lost electrons b. have gained electrons c. have lost electrons d. have gained protons

c. have lost electrons

d. energy

b. decrease

### An alpha particle (charge 2p, mass approximately 4mp) and an electron are in a constant electric field created by oppositely charged plates. You release the alpha particle from the positive side and the electron from the negative side. When it strikes the opposite side which one has more kinetic energy? A. they both acquire the same kinetic energy but with opposite signs B. both acquire the same kinetic energy C. electron D. alpha particle

A. they both acquire the same kinetic energy with opposite signs

B. 4.5C

B. decrease

### What is the magnitude of the acceleration of an electron that is in an electric field of 600 N / C? A. 600 m / s2 B. 5.7 x 10`10 m / s2 C. 3.5 x 10`11 m / s2 D. 1.1 x 10`14 m / s2

D.1.1 x 10`14 m / s2

D. 4.4nC

### Electric field lines A. radiate outward from positive charges. B. circle counter-clockwise around positive charges. C. circle clockwise around positive charges. D. radiate outward from negative charges.

A. radiate outward from positive charges.

### Which statement about equipotential lines is true. A. They always run parallel to each other. B. They cross perpendicularly to the electric field lines. C. Their density tells you the strength of the potential. D. They start on negative charges and end on positive charges.

B. They cross perpendicularly to the electric field lines

### Which has the higher resistance, a 100-W light bulb or a 75-W light bulb? Assume that both light bulbs are designed to be connected to normal AC power. A. 100-W light bulb B. 75-W light bulb C. resistance is the same D. can not be determined

B. 75-W light bulb

A. .34Amps

### At twice the distance from a point charge, the strength of the electric potential due to the charges is A. one-half its original value. B. one-fourth its original value. C. can't answer without knowing the charge D. twice its original value.

A. one-half its original value

D.high voltage

C. 2.5ohms

### The electrical energy supplied by a battery comes from A. Charge stored on two isolated plates. B. The heat produced by an exothermic reaction. C. Chemical energy. D. The magnetic force between two different metals.

C. chemical energy

### A resistor is ohmic if its resistance A. changes proportionally to the voltage. B. changes proportionally to the current. C. does not change with voltage or current. D. decreases with temperature.

C. does not change with voltage or current

C. 32V

A. 9.0 C

A. increase

### What is the magnitude of the acceleration of a proton that is in an electric field of 300 N / C? A. 5.3 x 10`13 m / s2 B. 5.7 x 10`10 m / s2 C. 2.9 x 10`10 m / s2 D. 9.6 x 10`17 m / s2

C. 2.9 x 10'10 m / s2

### Two point charges are separated by 10 meters. If the distance between them is reduced to 5.0 meters, the magnitude of the electrostatic force exerted on each: A. decreases to half its original value B. increases to twice its original value C. decreases to one quarter of its original value D. increases to four times its original value

D. increases to four time its original value

### Electric field lines A. radiate outward from negative charges. B. circle counter-clockwise around positive charges. C. circle clockwise around positive charges. D. radiate outward from positive charges

D, radiate outward from positive charges

### Which of the following statements is true. A. Electric field lines cannot cross, but equipotential lines may cross. B. Both electric field lines and equipotential lines may cross. C. Both electric field lines equipotential lines can not cross. D. Electric field lines can cross but equipotential lines cannot cross.

C. both electric field lines are equipotential lines can not cross

### Two charges lie along the x axis at x=1 and x=10. The charge at x=1 is -2 C and the charge at x=10 is +5 C. Where will the electric field due to these two particles be zero? A. To the right of x=10. B. Between x=1 and x=10. C. To the left of x=1. D. Both between x=1 and 10 and below x=1.

C. to the left of x=1

A. 10 ohms

### The electric potential V, due to a negative charge, is zero at infinity and A. positive everywhere else. B. negative everywhere else. C. positive if a second negative charge is nearby. D. negative if a second negative charge is nearby.

B. negative everywhere else

### A resistor is ohmic if its resistance A. is proportional to the voltage. B. is proportional to the current. C. does not change with voltage or current. D. decreases with temperature

C. does not change with voltage or current

A. 9.6X10-11 J

D. 1.2X10'4 N/C

D. 9.2 x 10-9 N

C. 600eV

D. 1.35x10`4 N/C

### What is the magnitude of the acceleration of an electron that is in an electric field of 200 N/C? A. 600 m / s2 B. 5.7 x 1010 m / s2 C. 3.5 x 1013 m / s2 D. 9.6 x 10-17 m / s2 E. none of the above

C. 3.5 x 10-7 m / s2

A. 12 J

B. 1.1x10-4 F

D. 150V

### What is the magnitude of the acceleration of a proton that is in an electric field of 600 N / C? A. 600 m / s2 B. 5.7 x 10`10 m / s2 C. 3.5 x 10`11 m / s2 D. 9.6 x 10`17 m / s2 E. none of the above

B. 5.7 x 10`10 m/ s2

B. 2.0x10`6 N/C

D. 900 eV

B. 1.25 A

D. 1.2X10`4 N/C

C. 2.0 C

D. 12 V

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