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1) An alternating current or voltage_____________________? a. fluctuates off and on b. varies in magnitude alone c. changes its direction again and again d. changes its magnitude harmonically and reverses its direction of flow after regularly recurring intervals
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2) Electromagnetic waves travel in free space with the speed of___________________? a. λ-rays b. Positive rays c. Cathode rays d. More than sound waves
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3) An electromagnetic wave consists of _____________________? a. Electric and magnetic fields moving parallel to each other b. Magnetic field moving with velocity of light in space c. Electric field moving with velocity of light d. Electric and magnetic fields moving perpendicular to each other
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4) Waves emitted from the antenna are__________________? a. Sound waves b. Electromagnetic waves c. Radio waves d. Modulated waves
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5) If capacitance of L-C circuit is made four times then frequency of the circuit becomes___________________? a. Twice b. One half c. Four times d. None
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6) The value of the steady current which when flowing through the same resistor produces heat at the same rate as the mean rate of heat produced by the alternating current is__________________? a. Average current b. Sinusoidal current c. r.m.s current d. Net current
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7) An alternating current of the r.m.s value of 4.0 A and frequency 50Hz flows in a circuit containing a 10Ω resistor. The peak current is then ? a. 20A b. 20.66A c. 6.66A d. 5.66A
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8) A changing magnetic flux produces around itself an induced_______________? a. Magnetic field b. Electric field c. Electromagnetic force d. Artificial gravitational field
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9) The direction of propagation of an electromagnetic waves is________________? a. Perpendicular to electric field b. Perpendicular to both electric and magnetic field c. Perpendicular to magnetic field d. Parallel to electric and magnetic field
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10) Electromagnetic waves transport___________________? a. Energy b. Momentum c. Mass d. Heat
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11) Electromagnetic waves emitted from antenna are________________? a. Stationary b. Longitudinal c. Transverse d. All the above
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12) A capacitor of capacitance 30µF is charged by a constant current of 10mA. If initially, the capacitor was uncharged what is the time taken for the potential difference across the capacitor to reach 300V ? a. 0.9sec b. 15 sec c. 1.5x105sec d. 0.9x102sec
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13) To find the r.m.s value of an alternating current mathematically we need to have ________________? a. Mean value of I2 b. Square root of mean value of I2 c. Square root of I2 d. Square of 1/2
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14) An alternating current is represented by the equation I = I∫sinπt which of the following equation represents an alternating current of frequency and amplitude twice that of the above current ? a. I = 2I∫Sin(πt/2) b. I = 2I∫Sin(2πt) c. I = 2ISinπt d. I = I∫sin(2πt)
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15) pure resistor circuit the voltage and current are_______________? a. Lagging each other b. They are at 90? phase difference c. They have zero phase difference d. No phase difference
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16) When A.C current passes through a capacitor then the current relationship will be_______________? a. The current lead voltage by phase angle is 90 degrees b. The voltage leads current by phase angle is 90 degrees c. The current lead voltage by phase angle is 45 degrees d. The voltage leads current by phase angle is 45 degrees
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17) In the capacitive circuit the current___________________? a. Lags behind voltage by π/2 b. Is in phase with voltage c. Opposite in phase of voltage by π d. Leads forward the voltage by π/2
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18) A 100µF capacitor with a 12V source in series having frequency 50Hz will offer a capacitive reactance of about______________? a. 32Ω b. 62Ω c. 50Ω d. 100Ω
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19) If a glass plate is inserted in between the plate of a capacitor in series with a lighted bulb the brightness of the bulb________________? a. Remains same b. Brightness increases c. Brightness decreases d. No light
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20) A wire of resistance R is coiled inductively so that its inductance is L. The impedance of the coil at a frequency of f is_______________? a. (R+2πfL) b. R+1/2πfL c. (R2+f2L2) d. (R2+4π2f2L2)
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21) Ammeter connected in an AC circuit measures______________? a. The exact value of the current b. RMS value of the current c. The net value of the current d. The peak value of the current
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22) When a pure inductor of inductance L and a pure capacitor of capacitance C are connected in parallel to a sinusoidal potential difference V the potential difference across both L & C will be_______________? a. Same b. Different c. At L will be more than at C d. At L will be less than at C
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23) What is the self-inductance of a coil in which an induced emf of 2V is set up when the current changes at the rate of 4 As-1 ? a. 0.5 mH b. 0.5H c. 2.0H d. 8.0H
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24) The frequency of a circuit consisting of a capacitance C and a resistor R is________________? a. C/R b. R/C c. 1/RC d. 1/ 2RC
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25) A 10Ω electric heater is connected to a 220V 50Hz mains supply. What is the peak value of the potential difference across the heater element ? a. 220V b. 220/ 2V c. 110V d. 220 √2V
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26) A choke is used as a resistance in_________________? a. DC circuit b. AC circuits c. Both AC and DC circuit d. Full wave rectifier circuit
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27) At resonance the value of the power factor in an L-C-R series circuit is_______________? a. Zero b. 2 c. 1 d. Not definite
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28) An A.C series circuit containing 4Ω resistance and 3Ω inductive reactance. The impedance of the circuit is______________? a. 1Ω b. 5Ω c. 7Ω d. 7Ω
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29) An inductive coil has a resistance of 100Ω. When an AC signal of frequency 1000Hz is fed to the coil the applied voltage leads the current by 45Ω. What is the inductance of the coil ? a. 10mH b. 12mH c. 16mH d. 20mH
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30) Choose the correct statement. In the case of AC circuit ohms law holds for_______________? a. Peak values of voltage and current b. Effective values of voltage and current c. Instantaneous values of voltage and current d. All of the above
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31) The phase angle between the voltage and the current in an AC circuit consisting of a resistance is______________? a. Zero b. 45° c. 90° d. 180°
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32) n an LCR series circuit, if V is the effective value of the applied voltage VR is the voltage across R VL is the effective voltage across L & Vc is the effective voltage across C a. V = VR+VL+VC b. V2 = VR2+VL2+VC2 c. V2 = VR2+(VL-VC)2 d. V2 = VL2+(VR-VC)2
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33) A voltage V = V0 cos ωt is applied across a resistor of resistance R the average power dissipated per cycle in the resistor is given by___________? a. V√/√2R b. V/√2√R c. V02/√2R d. 2/√2√R
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34) Two identical coaxial circular loops carry equal currents in the same direction. If the loops approach each other the current in______________? a. Each increase b. Each decrease c. Each remains the same d. One increases whereas that in the other decreases
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35) An inductor may store energy in ________________? a. Its electric field b. Its coils c. Its magnetic field d. Both electric and magnetic fields
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36) Addition of vector obeys_____________? a. Commutative law b. Distributive law c. Associative law d. All given laws in A, B and C
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37) The direction of a vector in space is specified by_______________? a. One angle b. Two angle c. Three angle d. No angle
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38) A vector can be multiplied by a number. The number may be_______________? a. Dimensionless b. Dimensional scalar c. Negative d. All A, B and C are correct
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39) Unit vector n^ is along______________? a. X-axis b. Normal on a surface c. Y-axis d. Z-axis
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40) The rectangular coordinate system is also called______________? a. Polar coordinate system b. Cartesian coordinate system c. Cylindrical coordinate system d. Spherical coordinate system
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