4. Suppose a 48-turn coil lies in the plane of the page in a uniform magnetic field that is directed out of the page. The coil originally has an area of 0.175 m². It is stretched to have no area in 0.100 s.What is the magnitude (in V) and direction (as seen from above) of the average induced emf if the uniform magnetic field has a strength of 1.30 T?magnitude V

8. Calculate the peak voltage (in V) of a generator that rotates its 215 turn, 0.100 m diameter coil at 3600 rpm in a 0.810 T field. V

9. At what velocity (in revolutions per minute) will the peak voltage of a generator be460V, if its480turn, 8.00 cm diameter coil rotates in a0.250 Tfield? rpm

10.Suppose a motor connected to a 115 V source draws 18.0 A when it first starts.(a)What is its resistance (in )? (b)What current (in A) does it draw at its normal operating speed when it develops a 100 V back emf? A

11. The motor in a toy car is powered by four batteries in series, which produce a total emf of 6.00 V. The motor draws 2.50 A and develops a 4.50 V back emf at normal speed. Each battery has a 0.105 internal resistance. What is the resistance (in ) of the motor

12 A cassette recorder uses a plug-in transformer to convert 120 V to15.0V, with a maximum current output of430mA.(a)What is the current input (in mA)? mA(b)What is the power input (in W)?

13.(a)What is the voltage output (in V) of a transformer used for rechargeable flashlight batteries, if its primary has 490 turns, its secondary 8 turns, and the input voltage is 116 V? V(b)What input current (in mA) is required to produce a 4.00 A output? mA(c)What is the power input (in W)? W

15 Two coils are placed close together in a physics lab to demonstrate Faraday's law of induction. A current of 4.00 A in one is switched off in 1.10 ms, inducing a 3.00 V emf in the other. What is their mutual inductance (in mH)? mH

16Camera flashes charge a capacitor to high voltage by switching the current through an inductor on and off rapidly. In what time (in s) must the 0.130 A current through a 2.20 mH inductor be switched on or off to induce a 460 V emf? s

17 If you want a characteristic RL time constant of 6.00 s, and you have a 445 resistor, what value of self-inductance (in H) is needed? H

18Your RL circuit has a characteristic time constant of 18.5 ns, and a resistance of 5.20 M.(a)What is the inductance (in H) of the circuit? H(b)What resistance (in M) should you use (instead of the 5.20 M resistor) to obtain a 1.00 ns time constant, perhaps needed for quick response in an oscilloscope? M

19.At what frequency (in Hz) will a 10.0 mH inductor have a reactance of 790 ? Hz

20What capacitance (in nF) should be used to produce a 1.30 M reactance at 62.0 Hz? nF

21. (a)Find the current (in A) through a 0.550 H inductor connected to a 60.0 Hz, 530 V AC source. A(b)What would the current be (in A) at 100 kHz? A