**Unformatted text preview: **PHY2054 TEST III MULTIPLE CHOICE (8 points each). Choose the one alternative that best completes the statement or answers the question. 1) An alternating current is supplied to an electronic component with a rating that it be used only for voltages
below 16 V. What is the highest VI.ms that can be supplied to this component while staying below the voltage limit?
8) M v @li v A) 256 V
2) The primary coil of a transformer has 600 turns and its secondary coil has 150 turns. It the AC current in the primary coil is 2 A, what is the current in its secondary coil? I A)0.5A B)4A C)2A
3) A 120 V rms voltage at 100 Hz is applied to a 200 mH inductor, a 4 pF capacitor and a resistor. [f the rrns
value of the current in the circuit is 0.4 A, what is the value of the resii r? D)8V A) 50.5 o B) 250.5 0 C) 100.1 0 Q 25.5 o E) 200.5 0 4) The phase angle of an RLC series circuit operating at 1000 Hz is 40 degrees. The circuit has an inductive
reactance of 200 Q and a resistor of 200 Q. What is the value of the ca L. 'tance in the drcuit? A) 1.95 p]: B) 2.95 at: C) 3.95 pr: a) .95 HF 5) An RLC circuit has a resistance of 2.0 k0, a capacitance of 8.0 “F, and an inductance of 9.0 H. If the
frequency of the AC current is 4.0/7! kHz, what is the phase 5%”: between the voltage and the current ? E) 5.95 or A) 1.0 rad B) 3.1 rad .5 rad D) 2.5 rad 6) A 120 V rms vlotage at 60 Hz is applied to an RC circuit. The rms current is 0.6 A and it leads the voltage by
60 degrees. What is the value of the resistance in the circuit?
‘3 n D A) 1200 B)600 02000 E) 1800 Figure 1 7) In Figure 1, a bar magnet moves away from the solenoid. The induced current rough the resistor R is:
A) zero 8) from b to a om a to b 8) A 5 H inductor carries a current of 2 amps. How can a self-induced EMF of 50 volts be made to appear
across the inductor?
A Change the current to 10 amps.
at hange the current at the rate of 10 amps/sec.
C) Break the circuit instantaneously.
D) Change the current uniformly to zero in 20 seconds.
E) None of these. 1) 2) 3) 4) 5) 6) 7) 3) 9) An RL circuit consists of a switch, an emf source £0, a 5.0 K) resistor, and a 4.0 H inductor. If the potential 9)
across the resistor is 65.0 V at 2.0 ms after the switch is closed, ﬁnd the source emf, so. A)36V B)56V @w D)76V
10) A large electromagnet has a 22 T magnetic ﬁeld between its poles. What is the magnetic energy density 10)
between the poles?
J/cm3 3) 30,000 J/cm3 C) 240 J/cm3 D) as J/cm3 Regular problems (10 points each) 1]. In Figure 2, there is a uniform magnetic field of magnitude B = 2.8 T and directed into the plane of the paper in the region shown.
Outside this region the magnetic ﬁeld is zero. A rectangular loop 0.20 m by 0.60 m and of resistance 2 0 is being pulled into the
magnetic field by an external force, as shown. (a) What is the direction (clockwise or counterclockwise) of the current induced in the loop? (b) Calculate the magnitude of the external force Fe,“ required to move the loop at a constant speed of v = 3.9 m/s. The mass of the loop is 0.008 kg. 0‘) CF : AB AZO-ZK 332‘9<T‘ Figure2
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- Fall '09
- RODRIGUEZ
- Physics, Alternating Current, Magnetic Field, Inductor, primary coil, RLC series circuit, secondary coil