Download Practice Quiz 9

Practice Quiz 10
1) A simple RL circuit contains a 6.0- Ω resistor and 18-H inductor. What is this circuit time constant?
A) 108 s
B) 3.0 s
C) 0.33 s
D) None of above
Answer: B
2) A 4.0 mH coil carries a current of 5.0 A. How much energy is stored in the coil’s magnetic field?
A) 2.0 mJ
B) 10 mJ
C) 20 mJ
D) None of above
Answer: D
3) An air filled solenoid has an inductance L. The solenoid is then filled with iron core of permeability 2000 µ The
inductance of the coil is now?
A) still L
B) 5.0 × 10-4 L
C) 2000 L
D) 4.0 × 106 L
Answer: C
4) A simple RL circuit contains a 12.0- Ω resistor and 35-mH inductor, an 18-V battery and a switch. When the
switch is closed, what is the initial current in the circuit?
A) 0.2 A
B) 0.27 A
C) 0.75 A
D) 0 A
Answer: D
5) In an LC circuit with an inductance of 40 mH and capacitance of 1.2 mF, the maximum charge on the capacitor is
45 mC during the oscillations which occur. What is the maximum current through the inductor during the
oscillations?
A) 0.2 A
B) 6.5 A
C) 0.75 A
D) 0 A
Answer: B
6) Tripling the number of turns of solenoid of fixed length L causes self-inductance to
A) increase by factor 3
B) decrease by factor 3
C) increase by factor 9
D) decrease by factor 9
Answer: C
7) The SI unit for self-inductance is
A) the henry
B) the self henry
C) Volt x Second
D) Volt/Second
Answer: C
8) What is the energy density in the magnetic field 25 cm from a long straight wire?
A) still L
B) 5.0 × 10-4 L
C) 2000 L
D) 4.0 × 106 L
Answer: C
9) At what rate would the current in a 100 mH inductor have to change to induce an emf of 1000 V?
A) 10 A/s
B) 100 A/s
C) 1.000 A/s
D) 10.000 A/s
Answer: A
10) As the current is increased in a conductor energy is stored in the associated magnetic field. At what current
would the energy stored be half the energy stored when the current is 20 A?
A) 0.2 A
B) 0.27 A
C) 14 A
D) 0 A
Answer: C
11) The H equal
A) one Vx s/A
B) one Ω x s
C) both a) and b)
D) neither a) and b)
Answer: C