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Transcript
Magnetostatics(3.2)
1. Who gave a simple explanation for the direction of the induced current in a loop
when the magnetic flux through the plane of the loop changes?
A) Ampere
B) Faraday
C) Lenz
D) Maxwell
2. The inductance of a multi-turn coil depends on Ans:C
A) current through coil
B) rate of change of current through coil
C) geometry of coil
D) voltage across the coil
3. The unit of inductance (henry) is equivalent to
A) Wb/A
B) N/A
C) T/A
D) A/T
Ans:A
E) A/Wb
4. Using inductance to shift from measuring flux changes to measuring current
changes simplifies the use of whose law? Ans:D
A) Gauss
B) Ampere
C) Coulomb
D) Faraday
5. What is the energy stored in a solenoidal inductor carrying a steady current I ? Ans:C
A) L2I/2
B) IL/2
C) I2L/2
D) I2L2/2
E) 0
6. When a battery (V) is connected across a series R-L combination, the current
will approach a final value of
Ans:A
A) V/R
B) VR
C) V/L
D) R/L
E) 0
7. The permittivity constant is generally denoted by
A) α
B) ε
C) μ
D) ρ
E) ω
Ans:B
8. Two identical coils have two different steady currents flowing through them. If
the current through the first coil is half the current through the second one, the
emf across the first coil, compared to the emf across the second, is
Ans:C
A) twice
B) half
C) same
9. If a series combination of a 0.1-H inductor and a 100-ohm resistor is connected
a cross a battery, how long will it take for the current to get within 1% of its final
value? Ans:E
A) 1
B) 2
C) 3
D) 4
E) 5
ms
10. In the circuit of Question 9, the voltage drop across the resistor will be
greatest
Ans:B
A) when the battery is first connected
B) a long time after the battery is connected
C) the voltage across the resistor is independent of time
Level 2
1. The MKS units of magnetic flux are
A. T
B. T m
C. T/m
D. T m2
2. A uniform magnetic field points directly into this page. An electron is moving towards the
right of the page. What is the direction of the magnetic force acting on the electron?
A. up, towards the top of the page.
B. down, towards the bottom of the page.
C. into the page.
D. out of the page.
3. A permanent magnet is made of a material which
A. is ferromagnetic.
B. has a permanent electric dipole moment.
C. has a non-zero net charge.
D. has a non-zero potential difference.
4. Two straight parallel wires 1 and 2 are separated by a distance D = 5.4 cm. The wires carry
currents I1 = 12.7 mA and I2 = 5.4 mA in opposite directions. What is the direction of the
external magnetic field felt by wire 2 due to the current flowing through wire 1?
A) Wire 2 moves towards wire 1
B) Wire 2 moves away from wire 1
C) can’t be said
D)None
5.In Question 4, What is the magnitude of the external magnetic field felt by wire 2 due to the
current flowing through wire 1?
A) 47 nT
B)27nT C)70nT
D)None
ANS: 1. D 2. B 3. A 4 B 5 A
Level 3
1. The magnetic force is felt by charges that are
Ans: B
A) larger than 1 C. B) moving. C) in magnets. D) in atoms. E) stationary.
2. The magnetic field produced by a current in a wire
Ans:A
A)encircles the wire.
B) points along the wire in the direction of current flow.
C)points along the wire opposite to the direction of current flow.
D) points directly away from the wire.
3. The magnetic force is always perpendicular to the magnetic field and to the
Ans:C
A)current flow.
B) charge feeling the force.
C)velocity.
D) plane formed by the magnetic field.
4. The magnetic north pole of a current loop is the region just above the loop where the magnetic field
Ans:C
A)points along the circumference of the loop along the direction of the current flow.
B)points along the circumference of the loop opposite to the direction of the current flow.
C)points out of the loop away from its center.
D) points into the loop toward its center.
5. A ferromagnetic material is a material that can have
Ans:D
A) a non-zero net charge.
B) motion relative to a given reference frame.
C) a current flowing through it.
D) a permanent magnetic field.
6. What is the direction of the magnetic force on the left section of the loop? Ans:A
A) Out of the screen
B)Into the screen
C)right
D)left
7.What is the total force on the loop? Ans:B
A) 5N
B)0
C)data insufficient
D)None
8.What is the direction of the magnetic force on the right section of the loop? Ans:B
A) Out of the screen
B)Into the screen
C)right
D)left
9.What happens if the loop is released?
A) it translates
B) it rotates
C)Data insufficient
D)None
Ans:B