# AC Circuits Questions and Answers

Physics

AC Circuitsthe source Voltage leads circuit current at known frequency f If f is lowered slightly the circuit impedance will 1 Increase 2 Decrease 3 Remain same 4 Need to know whether the phase angle is less than 45 or greater than 45

Physics

AC CircuitsThe current I time t according to the graph given below Which one of the following graphs gives the variation of voltage in the coil with time 1994 A B C D V t V A t V Ho V

Physics

AC CircuitsIn case of phase lag compensation used in system gain cross over frequency band width and undamped frequency are respectively 1 decreased decreased decreased 2 increased increased increased 3 increased increased decreased 4 increased decreased decreased

Physics

AC CircuitsThe equation of emf in an ac circuit is given by E 200 2 sin 200rt volt what is the minimum time taken for the emf to change from 200 V to 200 V 200 a 1 100 Icl 100s E b 200s d 1 200 s

Physics

AC CircuitsA town situated 20 km away from a power plant generating power at 440 V requires 600 kW of electric power at 200 V The resistance of the two wire line carrying power is 0 42 per km The town gets power from the line through a 3000 220 V step down transformer at a substation in the town i Find the line power losses in the form of heat ii How much power must the plant supply assuming there is negligible power loss due to leakage CBSE OD 03 19 CAO LIAZ

Physics

AC CircuitsA common emitter amplifier has a voltage gain of 50 an input impedance of 10002 and an output impedance of 2002 The power gain of the amplifier is a 500 2010 c 1250 b 1000 d 50

Physics

AC CircuitsOF The peak value of an alternating emf E given by E E cos oot is 10 V and its frequency is 50 Hz At a time t s the instantaneous value of the emf is 100 a 10 V c 5V The power loss in AC ci EET b 5 3 v d 1V it will be minimum when

Physics

AC Circuitssingle strand The self inductance of a choke coil is 10 mH When it is conected with a 10V D C source then the los of power is 20 watt When it is connected with 10 volt A C source loss of power is 10 watt Th frequency of A C source will be RPMT 1995 1 50 Hz 2 60 Hz 3 80 Hz 4 100 Hz If the frequency of the source e m f in an AC circuit is n the power varies with a frequency

Physics

AC Circuitsag ti An a 20 mH inductor and a 50 uF capacitor with an initial charge of 10 mC The resistance of the circuit is negligible this is som Let the instant the circuit is closed be t 0 le at a What is the total energy stored initially Is it conserved during LC oscillations b What is the natural frequency of the circuit c At what time is the energy stored I T Y completely electrical i e stored in the capacitor ii completely magnetic i e stored in the inductor 18 d At what times is the total energy shared equally between the inductor and the capacitor a resistor is inserted in the circuit how much energy is eventually dissipated as heat A coil of inductance 0 50 H and resistance 100 2 is connected to a 240 V 50 Hz ac supply imum current in the coil oltage maximum and the

Physics

AC CircuitsThe battery shown in figure is ideal The values are 10 V R 502L 2H current through the battery at t 2sect 1 Initially the current in the inductor is zero The is 2102 in Ampere Find Io Inductor is ideal EL

Physics

AC CircuitsA cone rolls without slipping on the horizontal surface so that its apex remains fixed and the axis of once is horizontal The radius of base of cone is 1 and the semi vertex angle is a The centre of bas of cone is C and it moves with constant speed vo Find the speed of point A and point B relative to surface ACB 90 Point A and B lies on circumference of the base of cone A 2v V 2 tan c B V V 2 tan a C 2V Vo 1 tan a 24 Front View

Physics

AC CircuitsA solenoid has an inductance of 20H and a resistance of 40 It is connected to a 20V battery How long will it take for the magnetic energy to reach 1 9th of its maximum value A 5ln 3 2 B 5ln 2

Physics

AC CircuitsJuctor in Figur ding all insulated metal wire around a core of soft magnetic material ferrite The cylindrical coil has 9 turns a length of 458 mm and a diameter of 16 mm The core has a relative permeability of 325 and negligible resistance End Y End X iii iv End P Oll Figure Q1a A cylindrical coil inductor At t 0 s the student completes a series circuit by connecting end X of the wire to the positive terminal of a power supply and end Y to a 10 2 resistor that was connected to the negative terminal of the supply The power supply has an emf of 12 V and a negligible internal resistance i i ii iii End Q a i Show that the inductance of this inductor is approximately 15 H Calculate the time constant of this LR circuit ii Calculate the current in the circuit at time t 3 us Calculate the time taken for the current in the circuit to reach 1 1 A The student leaves the inductor connected to the power supply until the current reaches a steady value b Calculate the magnitude of the magnetic field strength inside the inductor Which end P or Q of the inductor is the North pole State the name of the rule you have used to determine this How much magnetic flux is coming out of the North pole of the inductor Calculate the amount of energy stored within the magnetic field of the inductor The student now places the inductor and the 10 resistor in series with a 180 nF capacitor and an 80 kHz AC power supply of negligible internal resistance c Calculate the capacitive reactance the inductive reactance the impedance and the phase angle for this LCR circuit and hence draw a fully labelled phasor diagram showing all of these values Finally the student removes the AC power supply and uses the series inductor and capacitor combination from part c within a radio receiver circuit d Calculate the wavelength of the radio signal that this circuit will pick up 11 5 6 3

Physics

AC CircuitsA student constructs an inductor shown in Figure Q1a by winding an insulated metal wire around a core of soft magnetic material ferrite The cylindrical coil has 9 turns a length of 458 mm and a diameter of 16 mm The core has a relative permeability of 325 and negligible resistance End X End Y End P a i ii iii End Q Figure Q1a A cylindrical coil inductor At t 0 s the student completes a series circuit by connecting end X of the wire to the positive terminal of a power supply and end Y to a 10 2 resisto that was connected to the negative terminal of the supply The power supply has an emf of 12 V and a negligible internal resistance Show that the inductance of this inductor is approximately 15 H Calculate the time constant of this LR circuit Calculate the current in the circuit at time t 3 s

Physics

AC CircuitsIn the given A C circuit the r m s voltage of the source is 60 V then the r m s current passing through the source is 10 x A then the value of x is X 352 oooooooo 4 X 30 C 2 R 592 wwww Xc 192 X 792 H1 mmmmmmm C L

Physics

AC CircuitsA 150 F capacitor in series with a 1502 resistance is connected to a 200 V 50 Hz supply a Determine the average power dissipated per cycle of the AC b Determine the current amplitude in the circuit c Determine the time lag between the current maximum and the voltage maximum d Determine the impedance of the circuit n of