Question

Use the figure at the right for problems 1 and 2. 2nswers. The [6] 1. A 5.61 m2 resistor, 1.55 pH inductor and switch are connected in series across an ideal EMF source E 9.50 V. How much energy is stored in the magnetic field of the inductor when switch S is closed and the magnetic field becomes stable? Answer: (a) 1.88 J. (b) 2.22 J (c) 2.77 J. (d) 3.20 J. (e) 3.79 J (0 [6] 2. In the previous problem, how long after switch S is closed until the magnetic field is stable? Answer: (a) 1.38 ms. (b) 1.85 ms. (c) 2.33 ms. (d) 2.79 ms (e) 3.41 ms [8] 3. An AC generator is connected to a circuit. The generator's emf is Ei)-152 V sin(a) Ifthe maimum curent that resuts is 150 mA circuit, a-5.01 x 107 rad/s and the phase angle is -85.6 degrees, complete the following it sin (ad- [8] 4. The amplitude of an alternating current is I-15.2 x 10 Amperes. What is value of I Answer: (a) 4.46 mA (b) 8.63 mA. (c) 10.7 mA (d) 13.6 mA (e) 18.5 mA (4] 5. In a series RLC circuit, the resistance is R= 25.4 m At a certain frequency the circuit is in resonance and the value of the inductive reactance at that time is X is 36.5 m Answer: (a) 0, At that time the capacitive reactance Xc must be (4) 36.5 m (e) 25.4 m (b) 12.7 m (e) 56.5 m [10] 6. Which of the following is (are) TRUE? Circle it (them) (a) A diamagnetic material is attracted to the poles of a magnet. (b) A transformer is a device that can be used to increase or decrease the amplitude of an alternating voltage. (c) A paramagnetic material is repelled by the poles of a magnet (d) A current carrying solenoid is a good example of a magnetic dipole. (e) Magnetic field lines form closed loops. [13] 7. The magnetic field through the conducting square loop at the right changes according to the relation B(t)- 2.5r-6.8t +5 T, where t is in seconds. Each side of the square is 321 cm long and the resistance is 56.8 u Determine the current (magnitude and direction) in the loop at t=5.6 seconds? (Hint: For the direction of the current you need determine if the magnetic field is increasing or decreasing with time.) Answer: (a) 1.19 x 10 A (d) 19.9 x 10 A (c) 9.80 x 10 A A. (b) 3.85 x 10 A (0 (e) 36.5 x 10° A Direction: CCW or CW Circle each of the FALSE statement(s) below. [14] 8. Faraday's Law predicts that in a circuit containing an inductor and capacitor and oscillations are taking place, energy is aheately transferred between the inductor and the capacitor. (a) Gauss Law for electrostatics predicts that it is not possible to find an isolated north or an isolated south mapetic pole in natre (b) The North magnetic pole of the earth is somewhere near the northeast of Canada. (c) Gauss' Law for magnetism predicts that an electric field is produced by a changing magnetic fux. (d) suggests that it is not possible to find isolated electric charges in nature. Ampere-Marwell's Law (e) (D. The displacement current E)is an imaginary current that is related to a real changing of an electric field. (g) When an electric current exists in an inductor, energy is stored in the magnetic field that surrounds it

Answer 1

1 (4) given Iman = 15:2x10 3 A Irms=? formula uscd Irma= tnax Irmo 15-22103 Irma = 10.78 x103 A Irma = lunt ma Answey Irms = 10.7 mA