Question 1

An LC circuit has an oscillation frequency of 105 Hz. If C = 0.1 $\mu$F, then L must be about:

Accepted Answer

A)  10 mH 
B)  1 mH 
C)  25 $\mu$H 
D)  2.5 $\mu$H 
E)  1 pH 
A)  10 mH 
B)  1 mH 
C)  25 $\mu$H 
D)  2.5 $\mu$H 
E)  1 pH C

Question 2

A generator supplies 100 V to the primary coil of a transformer. The primary has 50 turns and the secondary has 500 turns. The secondary voltage is:

Accepted Answer

A)  1000 V 
B)  500 V 
C)  250 V 
D)  100 V 
E)  10 V 
A)  1000 V 
B)  500 V 
C)  250 V 
D)  100 V 
E)  10 V A

Question 3

In an ideal 1:8 step-down transformer, the primary power is 10 kW and the secondary current is 25 A. The primary voltage is:

Accepted Answer

A)  25,600 V 
B)  3200 V 
C)  400 V 
D)  50 V 
E)  6.25 V 
A)  25,600 V 
B)  3200 V 
C)  400 V 
D)  50 V 
E)  6.25 V B

Question 4

An RC series circuit is connected to an emf source having angular frequency $ \omega $. The current:

Accepted Answer

A)  leads the source emf by tan-1(1/$ \omega $CR) 
B)  lags the source emf by tan-1(1/$ \omega $CR) 
C)  leads the source emf by tan-1($ \omega $CR) 
D)  lags the source emf by tan-1($ \omega $CR) 
E)  leads the source emf by $\pi$/4 
A)  leads the source emf by tan-1(1/$ \omega $CR) 
B)  lags the source emf by tan-1(1/$ \omega $CR) 
C)  leads the source emf by tan-1($ \omega $CR) 
D)  lags the source emf by tan-1($ \omega $CR) 
E)  leads the source emf by $\pi$/4

Question 5

The resistance of the primary coil of a well designed, 1:10 step-down transformer is 1 $\Omega$ . With the secondary circuit open, the primary is connected to a 12 V ac generator. The primary current is:

Accepted Answer

A)  essentially zero 
B)  about 12 A 
C)  about 120 A 
D)  depends on the actual number of turns in the primary coil 
E)  depends on the core material 
A)  essentially zero 
B)  about 12 A 
C)  about 120 A 
D)  depends on the actual number of turns in the primary coil 
E)  depends on the core material

Question 6

An LC circuit consists of a 1 $\mu$F capacitor and a 4 mH inductor. Its oscillation frequency is approximately:

Accepted Answer

A)  0.025 Hz 
B)  25 Hz 
C)  60 Hz 
D)  2500 Hz 
E)  15,800 Hz 
A)  0.025 Hz 
B)  25 Hz 
C)  60 Hz 
D)  2500 Hz 
E)  15,800 Hz

Question 7

An RLC series circuit, connected to a source E, is at resonance. Then:

Accepted Answer

A)  the voltage across R is zero 
B)  the voltage across R equals the applied voltage 
C)  the voltage across C is zero 
D)  the voltage across L equals the applied voltage 
E)  the applied voltage and current differ in phase by 90 $\degree$ 
A)  the voltage across R is zero 
B)  the voltage across R equals the applied voltage 
C)  the voltage across C is zero 
D)  the voltage across L equals the applied voltage 
E)  the applied voltage and current differ in phase by 90 $\degree$

Question 8

An RLC series circuit is driven by a sinusoidal emf with angular frequency $ \omega $d. If $ \omega $d is increased without changing the amplitude of the emf the current amplitude increases. If the L is inductance, C is the capacitance, and R is the resistance, this means that:

Accepted Answer

A) $ \omega $dL > 1/$ \omega $dC B) $ \omega $dL dC C) $ \omega $dL = 1/$ \omega $dC D) $ \omega $dL > R E) $ \omega $dL < R A) $ \omega $dL > 1/$ \omega $dC B) $ \omega $dL dC C) $ \omega $dL = 1/$ \omega $dC D) $ \omega $dL > R E) $ \omega $dL < R

Question 9

A series RL circuit is connected to an emf source of angular frequency $ \omega $. The current:

Accepted Answer

A)  leads the applied emf by tan-1($ \omega $L/R) 
B)  lags the applied emf by tan-1($ \omega $L/R) 
C)  lags the applied emf by tan-1($ \omega $R/L) 
D)  leads the applied emf by tan-1($ \omega $R/L) 
E)  is zero 
A)  leads the applied emf by tan-1($ \omega $L/R) 
B)  lags the applied emf by tan-1($ \omega $L/R) 
C)  lags the applied emf by tan-1($ \omega $R/L) 
D)  leads the applied emf by tan-1($ \omega $R/L) 
E)  is zero

Question 10

An RLC circuit has a capacitance of 12$\mu$F, an inductance of 25 mH, and a resistance of 60  $\Omega$ . The current oscillates with an angular frequency of:

Accepted Answer

A)  1.2 * 103 rad/s 
B)  1.4 * 103 rad/s 
C)  1.8 * 103 rad/s 
D)  2.2 *103 rad/s 
E)  2.6* 103 rad/s 
A)  1.2 * 103 rad/s 
B)  1.4 * 103 rad/s 
C)  1.8 * 103 rad/s 
D)  2.2 *103 rad/s 
E)  2.6* 103 rad/s

Question 11

Consider the mechanical system consisting of two springs and a block, as shown. Which one of the five electrical circuits (I, II, III, IV, V) is the analog of the mechanical system?

Accepted Answer

A)  I 
B)  II 
C)  III 
D)  IV 
E)  V 
A)  I 
B)  II 
C)  III 
D)  IV 
E)  V

Question 12

In a sinusoidally driven series RLC circuit the current lags the applied emf. The rate at which energy is dissipated in the resistor can be increased by:

Accepted Answer

A)  decreasing the capacitance and making no other changes 
B)  increasing the capacitance and making no other changes 
C)  increasing the inductance and making no other changes 
D)  increasing the driving frequency and making no other changes 
E)  decreasing the amplitude of the driving emf and making no other changes 
A)  decreasing the capacitance and making no other changes 
B)  increasing the capacitance and making no other changes 
C)  increasing the inductance and making no other changes 
D)  increasing the driving frequency and making no other changes 
E)  decreasing the amplitude of the driving emf and making no other changes

Question 13

Iron, rather than copper, is used in the core of transformers because iron:

Accepted Answer

A)  can withstand a higher temperature 
B)  has a greater resistivity 
C)  has a very high permeability 
D)  makes a good permanent magnet 
E)  insulates the primary from the secondary 
A)  can withstand a higher temperature 
B)  has a greater resistivity 
C)  has a very high permeability 
D)  makes a good permanent magnet 
E)  insulates the primary from the secondary

Question 14

An RLC series circuit is connected to an oscillator with a maximum emf of = 100 V. If the voltage amplitudes VR, VL, and VC are all equal to each other, then VR must be:

Accepted Answer

A)  33 V 
B)  50 V 
C)  67 V 
D)  87 V 
E)  100 V 
A)  33 V 
B)  50 V 
C)  67 V 
D)  87 V 
E)  100 V

Question 15

In a purely inductive circuit, the current lags the voltage by:

Accepted Answer

A)  0 
B)  one-fourth of a cycle 
C)  one-half of a cycle 
D)  three-fourths of a cycle 
E)  one cycle 
A)  0 
B)  one-fourth of a cycle 
C)  one-half of a cycle 
D)  three-fourths of a cycle 
E)  one cycle

Question 16

The impedance of an RLC series circuit is definitely increased if:

Accepted Answer

A)  C decreases 
B)  L increases 
C)  L decreases 
D)  R increases 
E)  R decreases 
A)  C decreases 
B)  L increases 
C)  L decreases 
D)  R increases 
E)  R decreases

Question 17

We desire to make an LC circuit that oscillates at 100 Hz using an inductance of 2.5 H. We also need a capacitance of:

Accepted Answer

A)  1 F 
B)  1 mF 
C)  1 $\mu$F 
D)  100$\mu$F 
E)  1 pF 
A)  1 F 
B)  1 mF 
C)  1 $\mu$F 
D)  100$\mu$F 
E)  1 pF

Question 18

In a sinusoidally driven series RLC circuit, the inductive resistance is XL = 200 $\Omega$, the capacitive reactance is XC = 100$\Omega$ and the resistance is R = 50 $\Omega$. The current and applied emf would be in phase if:

Accepted Answer

A)  the resistance is increased to 100 $\Omega$, with no other changes 
B)  the resistance is increased to 200 $\Omega$, with no other changes 
C)  the inductance is reduced to zero, with no other changes 
D)  the capacitance is doubled, with no other changes 
E)  the capacitance is halved, with no other changes 
A)  the resistance is increased to 100 $\Omega$, with no other changes 
B)  the resistance is increased to 200 $\Omega$, with no other changes 
C)  the inductance is reduced to zero, with no other changes 
D)  the capacitance is doubled, with no other changes 
E)  the capacitance is halved, with no other changes

Question 19

An ac generator producing 10 V (rms) at 200 rad/s is connected in series with a 50-$\Omega$ resistor, a 400-mH inductor, and a 200-$\mu$F capacitor. The rms voltage (in volts) across the capacitor is:

Accepted Answer

A)  2.5 
B)  3.4 
C)  6.7 
D)  10.0 
E)  10.8 
A)  2.5 
B)  3.4 
C)  6.7 
D)  10.0 
E)  10.8

Question 20

The angular frequency of a certain RLC series circuit is $ \omega $0. A source of sinusoidal emf, with angular frequency 2$ \omega $, is inserted into the circuit. After transients die out the angular frequency of the current oscillations is:

Accepted Answer

A)  $ \omega $0/2 
B)  $ \omega $0 
C)  2$ \omega $0 
D)  1.5$ \omega $0 
E)  3$ \omega $0 
A)  $ \omega $0/2 
B)  $ \omega $0 
C)  2$ \omega $0 
D)  1.5$ \omega $0 
E)  3$ \omega $0

Exam 31: Electromagnetic Oscillations and Alternating Current

An LC circuit has an oscillation frequency of 105 Hz. If C = 0.1 μ\muμ F, then L must be about:

A generator supplies 100 V to the primary coil of a transformer. The primary has 50 turns and the secondary has 500 turns. The secondary voltage is:

In an ideal 1:8 step-down transformer, the primary power is 10 kW and the secondary current is 25 A. The primary voltage is:

An RC series circuit is connected to an emf source having angular frequency ω \omega ω . The current:

The resistance of the primary coil of a well designed, 1:10 step-down transformer is 1 Ω\OmegaΩ . With the secondary circuit open, the primary is connected to a 12 V ac generator. The primary current is:

An LC circuit consists of a 1 μ\muμ F capacitor and a 4 mH inductor. Its oscillation frequency is approximately:

An RLC series circuit, connected to a source E, is at resonance. Then:

An RLC series circuit is driven by a sinusoidal emf with angular frequency ω \omega ω d. If ω \omega ω d is increased without changing the amplitude of the emf the current amplitude increases. If the L is inductance, C is the capacitance, and R is the resistance, this means that:

A series RL circuit is connected to an emf source of angular frequency ω \omega ω . The current:

An RLC circuit has a capacitance of 12 μ\muμ F, an inductance of 25 mH, and a resistance of 60 Ω\OmegaΩ . The current oscillates with an angular frequency of:

Consider the mechanical system consisting of two springs and a block, as shown. Which one of the five electrical circuits (I, II, III, IV, V) is the analog of the mechanical system?

In a sinusoidally driven series RLC circuit the current lags the applied emf. The rate at which energy is dissipated in the resistor can be increased by:

Iron, rather than copper, is used in the core of transformers because iron:

An RLC series circuit is connected to an oscillator with a maximum emf of = 100 V. If the voltage amplitudes VR, VL, and VC are all equal to each other, then VR must be:

In a purely inductive circuit, the current lags the voltage by:

The impedance of an RLC series circuit is definitely increased if:

We desire to make an LC circuit that oscillates at 100 Hz using an inductance of 2.5 H. We also need a capacitance of:

In a sinusoidally driven series RLC circuit, the inductive resistance is XL = 200 Ω\OmegaΩ , the capacitive reactance is XC = 100 Ω\OmegaΩ and the resistance is R = 50 Ω\OmegaΩ . The current and applied emf would be in phase if:

An ac generator producing 10 V (rms) at 200 rad/s is connected in series with a 50- Ω\OmegaΩ resistor, a 400-mH inductor, and a 200- μ\muμ F capacitor. The rms voltage (in volts) across the capacitor is:

The angular frequency of a certain RLC series circuit is ω \omega ω 0. A source of sinusoidal emf, with angular frequency 2 ω \omega ω , is inserted into the circuit. After transients die out the angular frequency of the current oscillations is:

Measurement

Motion Along a Straight Line

Vector

Motion in Two and Three Dimensions

Force and Motion I

Force and Motion II

Kinetic Energy and Work

Potential Energy and Conservation of Energy

Center of Mass and Linear Momentum

Rotation

Rolling, Torque, and Angular Momentum

Equilibrium and Elasticity

Gravitation

Fluids

Oscillations

Waves I

Waves II

Temperature, Heat, and the First Law of Thermodynamics

The Kinetic Theory of Gases

Entropy and the Second Law of Thermodynamics

Electric Charge

Electric Fields

Gauss Law

Electric Potential

Capacitance

Current and Resistance

Circuits

Magnetic Fields

Magnetic Fields Due to Currents

Induction and Inductance

Maxwells Equations; Magnetism of Matter

Electromagnetic Waves

Images

Interference

Diffraction

Relativity

Photons and Matter Waves

More About Matter Waves

All About Atoms

Conduction of Electricity in Solids

Nuclear Physics

Energy From the Nucleus

Quarks, Leptons, and the Big Bang

Filters

An LC circuit has an oscillation frequency of 10⁵ Hz. If C = 0.1 $\mu$ F, then L must be about:

An RC series circuit is connected to an emf source having angular frequency $\omega$ . The current:

The resistance of the primary coil of a well designed, 1:10 step-down transformer is 1 $\Omega$ . With the secondary circuit open, the primary is connected to a 12 V ac generator. The primary current is:

An LC circuit consists of a 1 $\mu$ F capacitor and a 4 mH inductor. Its oscillation frequency is approximately:

An RLC series circuit is driven by a sinusoidal emf with angular frequency $\omega$ _d. If $\omega$ _d is increased without changing the amplitude of the emf the current amplitude increases. If the L is inductance, C is the capacitance, and R is the resistance, this means that:

A series RL circuit is connected to an emf source of angular frequency $\omega$ . The current:

An RLC circuit has a capacitance of 12 $\mu$ F, an inductance of 25 mH, and a resistance of 60 $\Omega$ . The current oscillates with an angular frequency of:

An RLC series circuit is connected to an oscillator with a maximum emf of = 100 V. If the voltage amplitudes V_R, V_L, and V_C are all equal to each other, then V_R must be:

In a sinusoidally driven series RLC circuit, the inductive resistance is X_L = 200 $\Omega$ , the capacitive reactance is X_C = 100 $\Omega$ and the resistance is R = 50 $\Omega$ . The current and applied emf would be in phase if:

An ac generator producing 10 V (rms) at 200 rad/s is connected in series with a 50- $\Omega$ resistor, a 400-mH inductor, and a 200- $\mu$ F capacitor. The rms voltage (in volts) across the capacitor is:

The angular frequency of a certain RLC series circuit is $\omega$ ₀. A source of sinusoidal emf, with angular frequency 2 $\omega$ , is inserted into the circuit. After transients die out the angular frequency of the current oscillations is: