VIEWS: 2 PAGES: 7 POSTED ON: 1/1/2013 Public Domain
Please write step by step solutions Not just the answers only. Question 1 A square loop of wire is rotating around its vertical axis in a magnetic field of strength B = 0.06 T as shown in View A. The angular frequency of rotation is = 50 rad/s and the loop has a resistance of R = 5 . The length of one side of the square loop is W = 0.05 m. At the instant of time when the normal to the loop makes an angle of = 30 with respect to the B field, as shown in View B where 'N' represents the normal, calculate the current flowing in the loop. Note: View A would be the side view if = 90 or 270 . Enter I= A Question 2 A 195 turn coil has an area of 4.9 cm2 and rotates in a magnetic field of 0.5 T. (a) What frequency will generate a maximum emf of 10 V? Enter Hz [5 points] 0 attempt(s) made (maximum allowed for credit = 5) [after that, multiply credit by 0.5 up to 10 attempts] (b) If the coil rotates at 60 Hz, what is the maximum emf? Enter V Question 3 A circuit breaker is rated for a current of 15 A rms at a voltage of 240 V rms. (a) What is the largest value of Imax that the breaker can carry? Enter A [5 points] 0 attempt(s) made (maximum allowed for credit = 5) [after that, multiply credit by 0.5 up to 10 attempts] (b) What average power can be supplied by this circuit? Enter W Question 4 An inductor has a reactance of 115 ohm at 80 Hz. (a) What is its inductance? Enter H [5 points] 0 attempt(s) made (maximum allowed for credit = 5) [after that, multiply credit by 0.5 up to 10 attempts] (b) What is its reactance at 180 Hz? Enter ohm Question 5 At what frequency would the reactance of a 11 F capacitor equal that of a 1.4 mH inductor? Enter Hz Question 6 At what frequency is the reactance of a 3 F capacitor 20000 ? Enter Hz Question 7 Four resistors (R1 = 60 Ohms, R2 = 220 Ohms, R3 = 330 Ohms, and R4 = 480 Ohms), an ideal inductor (L = 8 mH), and a capacitor (C = 250 microF) are connected to a battery (V = 9 V) through a switch as shown in the figure below. The switch has been open for a long time before it is closed at t = 0. What is Ustored, the total stored energy in the circuit elements (not including the battery) a long time after the switch is closed? Enter Ustored = J Question 8 True or false: (a) An RLC circuit with a high Q factor has a narrow resonance curve. 1. true 2. false Enter [3.33 points] 0 attempt(s) made (maximum allowed for credit = 1) (b) At resonance, the impedance of a series RLC circuit equals the resistance R. 1. true 2. false Enter [3.33 points] 0 attempt(s) made (maximum allowed for credit = 1) (c) At resonance, the current and generator voltage are in phase. 1. true 2. false Enter Question 9 A 5 F capacitor is charged to 35 V and is then connected across a 9-mH inductor. (a) How much energy is stored in the system? Enter J [3.33 points] 0 attempt(s) made (maximum allowed for credit = 5) [after that, multiply credit by 0.5 up to 10 attempts] (b) What is the frequency of oscillation of the circuit? Enter Hz [3.33 points] 0 attempt(s) made (maximum allowed for credit = 5) [after that, multiply credit by 0.5 up to 10 attempts] (c) What is the maximum current in the circuit? Enter A Question 10 A resistance R and a 2.7-H inductance are in series across a 60-Hz ac voltage. The voltage across the resistor is 34 V and the voltage across the inductor is 23 V. Assume that all voltages in this problem are rms voltages. (a) What is the resistance R? Enter ohm [5 points] 0 attempt(s) made (maximum allowed for credit = 5) [after that, multiply credit by 0.5 up to 10 attempts] (b) What is the ac input voltage? Enter V Question 11 A series RLC circuit with L = 12 mH, C = 3.9 F, and R = 3.6 is driven by a generator with a maximum emf of 100 V and a variable angular frequency . (a) Find the resonant (angular) frequency 0. Enter rad/s [1.43 points] 0 attempt(s) made (maximum allowed for credit = 5) [after that, multiply credit by 0.5 up to 10 attempts] (b) Find Irms at resonance. Enter A [1.43 points] 0 attempt(s) made (maximum allowed for credit = 5) [after that, multiply credit by 0.5 up to 10 attempts] When the angular frequency = 8950 rad/s, (c) Find the capacitive reactance XC in ohms. Enter [1.43 points] 0 attempt(s) made (maximum allowed for credit = 5) [after that, multiply credit by 0.5 up to 10 attempts] Find the inductive reactance XL in ohms. Enter [1.43 points] 0 attempt(s) made (maximum allowed for credit = 5) [after that, multiply credit by 0.5 up to 10 attempts] (d) Find the impedance Z. (Give your answer in ohms.) Enter [1.43 points] 0 attempt(s) made (maximum allowed for credit = 5) [after that, multiply credit by 0.5 up to 10 attempts] Find Irms. Enter A [1.43 points] 0 attempt(s) made (maximum allowed for credit = 5) [after that, multiply credit by 0.5 up to 10 attempts] (e) Find the phase angle (in degrees). Enter degrees Question 12 The primary of a step-down transformer has 215 turns and is connected to a 120 V rms line. The secondary is to supply 29 A at 6 V. (a) Find the current in the primary. Enter A [5 points] 0 attempt(s) made (maximum allowed for credit = 5) [after that, multiply credit by 0.5 up to 10 attempts] (b) Find the number of turns in the secondary, assuming 100% efficiency. Enter