Physics 151Test Bank 2

Physics 151Test Bank 2

A rod with an unknown charge attracts a pith ball (as in the attempted lecture demonstration). Which of the following could describe the situation?

(A) The rod has negative charge and the pith ball has positive charge.

(B) The rod has positive charge and the pith ball has negative charge.

(C) They both have positive charge.

(D) They both have negative charge.

(E) Both A and B above.

A rod with an unknown charge repels a pith ball (as in the attempted lecture demonstration). Which of the following could describe the situation?

(A) The rod has negative charge and the pith ball has positive charge.

(B) The rod has positive charge and the pith ball has negative charge.

(C) They both have positive charge.

(D) They both have negative charge.

(E) Both C and D above.

The person who is generally attributed for the conventions for positive and negative charges is

(A) Archimedes.

(B) Aristotle.

(C) Ben Franklin.

(D) Alexander Graham Bell.

(E) Augustine de Coloumb.

Two charges attract each other with a force of 1x10-6 N. If the distance between the charges is doubled, then the force will

(A) become attractive.

(B) become 5x10-7 N.

(C) become 2.5x10-7 N.

(D) become 2x10-6 N.

(E) become 4x10-6 N.

An object has a positive electric charge whenever

(A) it has an excess of electrons.

(B) it has a deficit of electrons.

(C) the nuclei of its atoms are positively charged.

(D) the electrons of its atoms are positively charged.

The magnitude of the electric field in the region between two parallel oppositely charged metal plates is

(A) zero.

(B) uniform.

(C) greatest near the positive plate.

(D) greatest near the negative plate.

Electric field lines

(A) leave positive charges and enter negative charges.

(B) are close together where E is strong and far apart where E is weak.

(C) never cross.

(D) have the same patterns around a charged metal sphere as they do around a point charge.

(E) all of the above.

Total electric charge is conserved

(A) only when energy is conserved.

(B) only in conductors.

(C) only in insulators.

(D) always.

(E) never.

An electric field of magnitude 200V/m can be produced by applying a potential difference of 10V to a pair of metal plates separated by

(A) 2000 m.

(B) 20 m.

(C) .05 m.

(D) .0005 m.

When an electron and a proton are both accelerated from rest through the same size potential difference, then

(A) the electron will have more KE.

(B) the proton will have more KE.

(C) they will both have the same KE.

(D) electrons and protons do not have charge, and cannot be accelerated through an electric potential.

The dielectric constant of a material is

(A) the factor by which the capacitanceincreases when the material is inserted between the plates of a parallel plate capacitor.

(B) the factor by which the amount of chargespontaneouslyincreases when the material is inserted between the plates of a parallel plate capacitor.

(C) the factor by which the potential increases when the material is inserted between the plates of a parallel plate capacitor.

(D) the maximum electric field the material can withstand before dielectric breakdown.

The dielectric strength of a material is

(A) the factor by which the capacitance increases when the material is inserted between the plates of a parallel plate capacitor.

(B) the factor by which the amount of charge spontaneously increases when the material is inserted between the plates of a parallel plate capacitor.

(C) the factor by which the potential increases when the material is inserted between the plates of a parallel plate capacitor.

(D) the maximum electric field the material can withstand before dielectric breakdown.

The magnitude of the electric field in the region between two parallel oppositely charged metal plates is

(A) zero.

(B) uniform.

(C) greatest near the positive plate.

(D) greatest near the negative plate.

Electric Potential (measured in volts) is

(A) energy.

(B) potential energy per unit charge.

(C) force per unit charge.

(D) electric charge.

When an electron and a proton are both accelerated from rest through the same size potential difference, then

(A) the electron will have more KE.

(B) the proton will have more KE.

(C) they will both have the same KE.

(D) electrons and protons do not have charge, and cannot be accelerated through an electric potential.

The resistance of a conductor does not depend upon its

(A) mass.

(B) length.

(C) cross-sectional area.

(D) resistivity.

A rheostat

(A) can be used as an adjustable voltage divider.
(B) is a source of an EMF.
(C) is the result of a collision between charges.
(D) is the mechanism by which we create charge. /

The current versus voltage graph which best represents a device which obeys Ohm's Law:

(A)
/ (B)

(C)
/ (D)

(E) All of the above

Problems

Two charges, Q1 = -12 C and Q2 = +16 C are 3.0 meters apart.
(A) What is the electric field (magnitude and direction) at the point indicated, 1m from Q1 and 2 m from Q2?
(B) What is the electric force (magnitude and direction)on a charge of 5 C placed at the point indicated, 1m from Q1 and 2 m from Q2? /

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Two charges, Q1 = -2 C and Q2 = +8 C are 4.0 meters apart.
(A) What is the electric field (magnitude and direction) at a point indicated, 1m from Q1 and 3 m from Q2?
(B) What is the electric force (magnitude and direction)on a charge of 5 C placed halfway between them? /

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(A) For the two capacitors connected as shown, determine
a) the equivalent capacitance of the combination,
b) the potential difference across the equivalent capacitance,
c) the potential difference across each capacitor (C1 and C2).
d) the charge on each capacitor,
e) the energy stored in each capacitor /
(B) For the two capacitors connected as shown, determine
a) the equivalent capacitance of the combination,
b) the potential difference across the equivalent capacitance,
c) the charge on the equivalent capacitance
d) the charge on each capacitor,
e) the potential difference across each capacitor , and
f) the energy stored in each capacitor /

______

(A) For the two capacitors connected as shown, determine
a) the equivalent capacitance of the combination,
b) the potential difference across the equivalent capacitance,
c) the potential difference across each capacitor (C1 and C2).
d) the charge on each capacitor,
e) the energy stored in each capacitor /
(B) For the two capacitors connected as shown, determine
a) the equivalent capacitance of the combination,
b) the potential difference across the equivalent capacitance,
c) the charge on the equivalent capacitance
d) the charge on each capacitor,
e) the potential difference across each capacitor , and
f) the energy stored in each capacitor /

______

(A) For the two resistors connected as shown, determine
a) the equivalent resistance of the combination,
b) the potential difference across the equivalent resistance
c) the potential difference across each resistor.
d) the current through each resistor,
e) the power dissipated in each resistor /
(B) For the two resistors connected as shown, determine
a) the equivalent resistance of the combination,
b) the potential difference across the equivalent resistance
c) the current through the equivalent resistance,
d) the current through each resistor,
e) the potential difference across each resistor.
f) the power dissipated in each resistor /

______

(A) For the two resistors connected as shown, determine
a) the equivalent resistance of the combination,
b) the potential difference across the equivalent resistance
c) the potential difference across each resistor.
d) the current through each resistor,
e) the power dissipated in each resistor /
(B) For the two resistors connected as shown, determine
a) the equivalent resistance of the combination,
b) the potential difference across the equivalent resistance
c) the current through the equivalent resistance,
d) the current through each resistor,
e) the potential difference across each resistor.
f) the power dissipated in each resistor /

______

(A) For the two resistors connected as shown, determine
a) the equivalent resistance of the combination,
b) the potential difference across the equivalent resistance
c) the potential difference across each resistor.
d) the current through each resistor,
e) the power dissipated in each resistor /
(B) For the two resistors connected as shown, determine
a) the equivalent resistance of the combination,
b) the potential difference across the equivalent resistance
c) the current through the equivalent resistance,
d) the current through each resistor,
e) the potential difference across each resistor.
f) the power dissipated in each resistor /

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A potential difference of 30 kV is used to accelerate electrons from rest.

(a) What is the kinetic energy of the electrons in J?

(b) What is the speed of the electrons?

(c) What is the kinetic energy of the electrons in eV?

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How strong an electric field is required to support a particle with mass = 1g and charge = 10µC against the force of gravity?

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A 40  resistor is to be wound from platinum wire .10 mm in diameter. How much wire (i.e. what length) is needed? The resistivity of platinum is given by

 = 11x10-8 ( m).