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MCQOPTIONS
This section includes 12583 Mcqs, each offering curated multiple-choice questions to sharpen your Joint Entrance Exam - Main (JEE Main) knowledge and support exam preparation. Choose a topic below to get started.
| 3101. |
The primary of a transformer when connected to a dc battery of 10 volt draws a current of 1 mA. The I number of turns of the primary and secondary windings are 50 and 100 respectively The voltage in the secondary and the current drawn by the circuit in the secondary are respectively |
| A. | 20 V and 0.5 mA |
| B. | 20 V and 2.0 mA |
| C. | 10 V and 0.5 mA |
| D. | Zero and therefore no current |
| Answer» E. | |
| 3102. |
A transformer having efficiency of 90% is working on 200V and 3kW power supply. If the current in the secondary coil is 6A, the voltage across the secondary coil and the current in the primary coil respectively are: |
| A. | 300V, 15A |
| B. | 450V, 15A |
| C. | 450V, 13.5A |
| D. | 600V, 15A |
| Answer» C. 450V, 13.5A | |
| 3103. |
Figure shows three oscillating LC circuit with identical inductors and capacitors. If\[{{t}_{1}}\], \[{{t}_{2}}\], \[{{t}_{3}}\] are the time taken by the circuits I, II, III for fully discharge, then |
| A. | \[{{t}_{1}}>{{t}_{2}}>{{t}_{3}}\] |
| B. | \[{{t}_{1}}<{{t}_{2}}<{{t}_{3}}\] |
| C. | \[{{t}_{2}}<{{t}_{1}}<{{t}_{3}}\] |
| D. | \[{{t}_{3}}=\sqrt{{{t}_{1}}{{t}_{2}}}\] |
| Answer» D. \[{{t}_{3}}=\sqrt{{{t}_{1}}{{t}_{2}}}\] | |
| 3104. |
In an oscillating LC circuit with L = 50 mH and\[C=4.0\,\mu F\], the current is initially a maximum. How long will it take before the capacitor is fully discharged for the first time: |
| A. | \[7\times {{10}^{-4}}\,s\] |
| B. | \[14\times {{10}^{-4}}\,s\] |
| C. | \[28\times {{10}^{-4}}\,s\] |
| D. | none of these |
| Answer» B. \[14\times {{10}^{-4}}\,s\] | |
| 3105. |
In an ideal transformer, the voltage and the current in the primary coil are 200 V and 2 A, respectively. If the voltage in the secondary coil is 2000 V, the value of current in the secondary coil will be |
| A. | 0.2 A |
| B. | 2 A |
| C. | 0.416666666666667 |
| D. | 20 A |
| Answer» B. 2 A | |
| 3106. |
A transformer is used to light a 140 W, 24 V bulb from a 240 V a.c. mains. The current in the main cable is 0.7 A. The efficiency of the transformer is |
| A. | \[63.8\text{ }%\] |
| B. | \[83.3\text{ }%\] |
| C. | \[16.7%\] |
| D. | \[36.2%\] |
| Answer» C. \[16.7%\] | |
| 3107. |
If a direct current of value ampere is superimposed on an alternative current\[I=b\,\sin \,\omega t\] flowing through a wire, what is the effective value of the resulting current in the circuit? |
| A. | \[{{\left[ {{a}^{2}}-\frac{1}{2}{{b}^{2}} \right]}^{1/2}}\] |
| B. | \[{{\left[ {{a}^{2}}+{{b}^{2}} \right]}^{1/2}}\] |
| C. | \[{{\left[ \frac{{{a}^{2}}}{2}+{{b}^{2}} \right]}^{1/2}}\] |
| D. | \[{{\left[ {{a}^{2}}+\frac{{{b}^{2}}}{2} \right]}^{1/2}}\] |
| Answer» E. | |
| 3108. |
At t < 0, the capacitor is charged and the switch is opened. At t=0 the switch is closed. The shortest time T at which the charge on the capacitor will be zero is given by |
| A. | \[\pi \sqrt{LC}\] |
| B. | \[\frac{3}{2}\pi \sqrt{LC}\,\] |
| C. | \[\frac{\pi }{2}\sqrt{LC}\,\] |
| D. | \[2\pi \sqrt{LC}\,\] |
| Answer» D. \[2\pi \sqrt{LC}\,\] | |
| 3109. |
A step down transformer is connected to 2400 volts line and 80 amperes of current is found to flow in output load. The ratio of the turns in primary and secondary coil is 20:1. If transformer efficiency is 100%, then the current flowing in the primary coil will be |
| A. | 1600 amp |
| B. | 20 amp |
| C. | 4 amp |
| D. | 1.5 amp |
| Answer» D. 1.5 amp | |
| 3110. |
Figure shows an iron - cored transformer assumed to be 100% efficient. The ratio olf the secondary turns to the primary turns is 1:20. A 240 V ac supply is connected to the primary coil and a 6 W resistor is corrected to the secondary coil. What is the current in the primary coil? |
| A. | 0.10 A |
| B. | 0.14 A |
| C. | 2 A |
| D. | 40 A |
| Answer» B. 0.14 A | |
| 3111. |
Combination of two identical capacitors, a resistor R and a dc voltage source of voltage 6V is used in an experiment on a (C-R) circuit. It is found that for a parallel combination of the capacitor the time in which the voltage of the fully charged combination reduces to half its original voltage is 10 second. For series combination the time needed for reducing the voltage of the fully charged series combination by half is |
| A. | 10 second |
| B. | 5 second |
| C. | 2.5 second |
| D. | 20 second |
| Answer» D. 20 second | |
| 3112. |
In the circuit shown here, the point 'C' is kept connected to point 'A' till the current flowing through the circuit becomes constant. Afterward, suddenly, point 'C' is disconnected from point 'A' and connected to point 'B' at time t=0. Ratio of the voltage across resistance and the inductor at t = L/R will be equal to: |
| A. | \[\frac{e}{1-e}\] |
| B. | 1 |
| C. | -1 |
| D. | \[\frac{1-e}{e}\] |
| Answer» D. \[\frac{1-e}{e}\] | |
| 3113. |
A fully charged capacitor C with initial charge \[{{q}_{0}}\] is connected to a coil of self-inductance L at\[t=0.\]The time at which the energy is stored equally between the electric and the magnetic fields is: |
| A. | \[\frac{\pi }{4}\sqrt{LC}\] |
| B. | \[2\pi \sqrt{LC}\] |
| C. | \[\sqrt{LC}\] |
| D. | \[\pi \sqrt{LC}\] |
| Answer» B. \[2\pi \sqrt{LC}\] | |
| 3114. |
If we increase the driving frequency in a circuit with a purely capacitive load, then |
| A. | amplitude\[{{V}_{C}}\]increases |
| B. | amplitude\[{{V}_{C}}\]decreases |
| C. | amplitude\[{{i}_{C}}\]increases |
| D. | amplitude\[{{i}_{C}}\]decreases |
| Answer» D. amplitude\[{{i}_{C}}\]decreases | |
| 3115. |
In a series LCR circuit \[R=200\Omega \] and the voltage and the frequency of the main supply is 220V and 50 Hz respectively. On taking out the capacitance from the circuit the current lags behind the voltage by \[30{}^\circ \]. On taking out the inductor from the circuit the current leads the voltage by \[30{}^\circ \]. The power dissipated in the LCR circuit is |
| A. | 305 W |
| B. | 210W |
| C. | Zero W |
| D. | 242 W |
| Answer» E. | |
| 3116. |
An arc lamp requires a direct current of 10 A at 80 V to function. If it is connected to a 220 V (rms),50 Hz AC supply, the series inductor needed for it to work is close to : |
| A. | 0.044 H |
| B. | 0.065 H |
| C. | 80 H |
| D. | 0.08 H |
| Answer» C. 80 H | |
| 3117. |
In the circuit shown below, the key K is closed at t=0. The current through the battery is |
| A. | \[\frac{V{{R}_{1}}{{R}_{2}}}{\sqrt{R_{1}^{2}+R_{2}^{2}}}\] at t=0 and \[\frac{V}{{{R}_{2}}}\] at \[t=\infty \] |
| B. | \[\frac{V}{{{R}_{2}}}\] at t=0 and \[\frac{V({{R}_{1}}+{{R}_{2}})}{{{R}_{1}}{{R}_{2}}}\] at \[t=\infty \] |
| C. | \[\frac{V}{{{R}_{2}}}\] at t=0 and \[\frac{V{{R}_{1}}{{R}_{2}}}{\sqrt{R_{1}^{2}+R_{2}^{2}}}\] at \[t=\infty \] |
| D. | \[\frac{V({{R}_{1}}+{{R}_{2}})}{{{R}_{1}}{{R}_{2}}}\] at t=0 and \[\frac{V}{{{R}_{2}}}\] at \[t=\infty \] |
| Answer» D. \[\frac{V({{R}_{1}}+{{R}_{2}})}{{{R}_{1}}{{R}_{2}}}\] at t=0 and \[\frac{V}{{{R}_{2}}}\] at \[t=\infty \] | |
| 3118. |
In given RC circuit, capacitance of capacitor \[{{C}_{1}}=3\mu F\]and \[{{C}_{2}}=1\mu F\]. It is given that time constant of circuit between A and B is 3 millisecond. Value of R will be |
| A. | \[1\,\Omega \] |
| B. | \[10\,\Omega \] |
| C. | \[100\,\Omega \] |
| D. | \[1000\,\Omega \] |
| Answer» E. | |
| 3119. |
In an electrical circuit R, L, C and an a.c. voltage source are all connected in series. When L is removed from the circuit, the phase difference between the voltage the current in the circuit is\[\pi /3\]. If instead, C is removed from the circuit, the phase difference is again \[\pi /3\]. The power factor of the circuit is : |
| A. | \[1/2\] |
| B. | \[1/\sqrt{2}\] |
| C. | 1 |
| D. | \[\sqrt{3}/2\] |
| Answer» D. \[\sqrt{3}/2\] | |
| 3120. |
An LCR circuit contains resistance of 100 ohm and a supply of 200 volt at 300 radian angular frequency If only capacitance is taken out from the circuit and the rest of the circuit is joined, current lags behind the voltage by \[60{}^\circ \].If on the other hand, only inductor is taken out, the current leads by \[60{}^\circ \]with the applied voltage. The current flowing in the circuit is: |
| A. | 1 A |
| B. | 1.5 A |
| C. | 0.0833333333333333 |
| D. | 2.5 A |
| Answer» D. 2.5 A | |
| 3121. |
An ac source of angular frequency co is fed across a resistor R and a capacitor C in series. The current registered is I. If now the frequency of source is changed to \[\omega /3\] (but maintaining the same voltage), the current in the circuit is found to be halved. Then the ratio of reactance to resistance at the original frequency \[\omega \]is |
| A. | \[\sqrt{3/5}\] |
| B. | \[\sqrt{5/3}\] |
| C. | \[\sqrt{2/3}\] |
| D. | \[\sqrt{3/2}\] |
| Answer» B. \[\sqrt{5/3}\] | |
| 3122. |
In a uniform magnetic field of induction B a wire in the form of a semicircle of radius r rotates about the diameter of the circle with an angular frequency \[\omega \]. The axis of rotation is perpendicular to the field. If the total resistance of the circuit is R, the mean power generated per period of rotation is |
| A. | \[\frac{{{(B\pi r\omega )}^{2}}}{2R}\] |
| B. | \[\frac{{{(B\pi {{r}^{2}}\omega )}^{2}}}{8R}\] |
| C. | \[\frac{B\pi {{r}^{2}}\omega }{2R}\] |
| D. | \[\frac{{{(B\pi r{{\omega }^{2}})}^{2}}}{8R}\] |
| Answer» C. \[\frac{B\pi {{r}^{2}}\omega }{2R}\] | |
| 3123. |
Current in an ac circuit is given by\[i=3\,\sin \,\omega t+4\,\cos \,\omega t\] then |
| A. | rms value of current is 5 A |
| B. | mean value of this current in one half period will be \[6/\pi \] |
| C. | if voltage applied is \[V={{V}_{m\,}}\sin \,\omega t\] then the circuit must be containing resistance and capacitance. |
| D. | if voltage applied is \[V={{V}_{m}}\,\sin \,\omega t\], the circuit may contain resistance and inductance. |
| Answer» D. if voltage applied is \[V={{V}_{m}}\,\sin \,\omega t\], the circuit may contain resistance and inductance. | |
| 3124. |
In a series L-C-R circuit, \[C={{10}^{-11}}\] Farad, \[L={{10}^{-5}}\] Henry and R=100 Ohm, when a constant D.C. voltage E is applied to the circuit, the capacitor acquires a charge \[{{10}^{-9}}\,C\]. The D.C. source is replaced by a sinusoidal voltage source in which the peak voltage \[{{E}_{0}}\]is equal to the constant D.C. voltage E. At resonance the peak value of the charge acquired by the capacitor will be: |
| A. | \[{{10}^{-15}}\,C\] |
| B. | \[{{10}^{-6}}\,C\] |
| C. | \[{{10}^{-10}}\,C\] |
| D. | \[{{10}^{-8}}\,C\] |
| Answer» E. | |
| 3125. |
As shown in figure, value of inductive reactance \[{{X}_{L}}\] will be if source voltage is 100 volt |
| A. | \[40\,\Omega \] |
| B. | \[30\,\Omega \] |
| C. | \[50\,\Omega \] |
| D. | can have any value |
| Answer» D. can have any value | |
| 3126. |
An inductor \[20\times {{10}^{-3}}\] Henry, a capacitor \[100\,\mu F\]and a resistor \[50\,\Omega \] are connected in series across a source of EMF V=10 sin 314t. If resistance is removed from the circuit and the value of inductance is doubled, then the variation of current with time in the new circuit is - |
| A. | \[0.52\text{ }cos\text{ }314t\] |
| B. | \[0.52\text{ }sin\text{ }314t\] |
| C. | \[0.52\,\sin \,(314t+\pi /3)\] |
| D. | None of these |
| Answer» B. \[0.52\text{ }sin\text{ }314t\] | |
| 3127. |
LC circuit contains a 20 mH inductor and a \[50\,\mu F\]capacitor with an initial charge of 10 mC. The resistance of the circuit is negligible. Let the instant the circuit is closed at t=0. At what time is the energy stored completely magnetic? |
| A. | t=0 |
| B. | t=1.57 ms |
| C. | t=3.14 ms |
| D. | t= 6.28 ms |
| Answer» C. t=3.14 ms | |
| 3128. |
When the rms voltages \[{{V}_{L}}\], \[{{V}_{C}}\] and \[{{V}_{R}}\]are measured respectively across the inductor L, the capacitor C and the resistor R in a series LCR circuit connected to an AC source, it is found that the ratio \[{{V}_{L}}:{{V}_{C}}:{{V}_{R}}=1:2:3\]. If the rms voltage of the AC sources is 100 V, the \[{{V}_{R}}\] is close to: |
| A. | 50V |
| B. | 70V |
| C. | 90V |
| D. | 100V |
| Answer» D. 100V | |
| 3129. |
A series LR circuit is connected to an ac source of frequency \[\omega \] and the inductive reactance is equal to 2R. A capacitance of capacitive reactance equal to R is added in series with L and R. The ratio of the new power factor to the |
| A. | \[\sqrt{\frac{2}{3}}\] |
| B. | \[\sqrt{\frac{2}{5}}\] |
| C. | \[\sqrt{\frac{3}{2}}\] |
| D. | \[\sqrt{\frac{5}{2}}\] |
| Answer» E. | |
| 3130. |
A resistor of resistance R, capacitor of capacitance C and inductor of inductance L are connected in parallel to AC power source of voltage \[{{\varepsilon }_{0}}\,\sin \,\omega t\]. The maximum current through the resistance is half of the maximum current through the power source. Then value of R is |
| A. | \[\frac{\sqrt{3}}{\left| \left. \omega C-\frac{1}{\omega L} \right| \right.}\] |
| B. | \[\sqrt{3}\left. \left| \frac{1}{\omega C}-\omega L \right. \right|\] |
| C. | \[\sqrt{5}\left. \left| \frac{1}{\omega C}-\omega L \right. \right|\] |
| D. | None of these |
| Answer» B. \[\sqrt{3}\left. \left| \frac{1}{\omega C}-\omega L \right. \right|\] | |
| 3131. |
The current in an L-R circuit builds up to\[{{(3/4)}^{th}}\]of its steady state value in 4 seconds. The time constant of this circuit is |
| A. | \[\frac{1}{ln\,\,2}\sec \] |
| B. | \[\frac{2}{ln\,\,2}\sec \] |
| C. | \[\frac{3}{ln\,\,2}\sec \] |
| D. | \[\frac{4}{ln\,\,2}\sec \] |
| Answer» C. \[\frac{3}{ln\,\,2}\sec \] | |
| 3132. |
What is the amount of power delivered by the ac source in the circuit shown (in watts). |
| A. | 500 watt |
| B. | 1014 watt |
| C. | 1514 watt |
| D. | 2013 watt |
| Answer» D. 2013 watt | |
| 3133. |
Charges on the capacitors in four oscillating LC circuits vary as follows: (1) q=2 cos 4t, (2) q =4 cos t, (3) q = 3 cos 4t, (4) q = 4 cos 2t, with q in coulomb and t in second. In which circuit(s) current amplitude is greatest? |
| A. | (1) |
| B. | (2) |
| C. | (3) |
| D. | -4 |
| Answer» D. -4 | |
| 3134. |
In an L-C circuit shown in the figure, C=1F, L=4H at time t=0, charge in the capacitor is 4C and it is decreasing at a rate of\[\sqrt{5}\,C/s\]. Choose the correct statements. |
| A. | maximum charge in the capacitor can be 6C |
| B. | maximum charge in the capacitor can be 8C |
| C. | charge in the capacitor will be maximum after time \[2\,{{\sin }^{-1}}\](2/3) sec |
| D. | None of these |
| Answer» B. maximum charge in the capacitor can be 8C | |
| 3135. |
An LCR series circuit with \[100\,\Omega \] resistance is connected to an AC source of 200 V and angular frequency 300 radians per second. When only the capacitance is removed, the current lags behind the voltage by \[60{}^\circ \]. When only the inductance is removed, the current leads the voltage by \[60{}^\circ \]. Then the current and power dissipated in LCR circuit are respectively |
| A. | 1A, 200 watt |
| B. | 1A, 400 watt |
| C. | 2A, 200 watt |
| D. | 2A, 400 watt |
| Answer» E. | |
| 3136. |
A resistor and an inductor are connected to an ac supply of 120 V and 50 Hz. The current in the circuit is 3 A. If the power consumed in the circuit is 108 W, then the resistance in the circuit is |
| A. | \[12\,\Omega \] |
| B. | \[40\,\Omega \] |
| C. | \[\sqrt{(52\times 25)}\Omega \] |
| D. | \[360\,\Omega \] |
| Answer» B. \[40\,\Omega \] | |
| 3137. |
The power factor in a circuit connected to an A.C. The value of power factor is |
| A. | unity when the circuit contains an ideal inductance only |
| B. | unity when the circuit contains an ideal resistance only |
| C. | zero when the circuit contains an ideal resistance only |
| D. | unity when the circuit contains an ideal capacitance only |
| Answer» C. zero when the circuit contains an ideal resistance only | |
| 3138. |
The two capacitors, shown in the circuit, are initially uncharged and the cell is ideal. The switch S is closed at t=0. Which of the following functions represents the current i(t) through the cell as a function of time? Here\[{{i}_{0}},\,{{i}_{1}},\,{{i}_{2}}\]are constants. |
| A. | \[i(t)={{i}_{0}}+{{i}_{1}}{{e}^{-t/\tau }}\]; \[\tau =3C\times \frac{R}{3}\] |
| B. | \[i(t)={{i}_{0}}+{{i}_{1}}{{e}^{-t/\tau }}+{{i}_{2}}{{e}^{-t/2\tau }}\]; \[\tau =RC\] |
| C. | \[i(t)={{i}_{1}}+{{i}_{1}}{{e}^{-t/\tau }}\]; \[\tau =3C\times \frac{R}{3}\] |
| D. | \[i(t)={{i}_{0}}+{{i}_{1}}{{e}^{-t/\tau }}\]; \[\tau =3RC\] |
| Answer» C. \[i(t)={{i}_{1}}+{{i}_{1}}{{e}^{-t/\tau }}\]; \[\tau =3C\times \frac{R}{3}\] | |
| 3139. |
A coil of inductive reactance \[31\,\Omega \]has a resistance of \[8\,\Omega \]. It is placed in series with a condenser of capacitive reactance \[25\,\Omega \]. The combination is connected to an a.c. source of 110 volt. The power factor of the circuit is |
| A. | 0.64 |
| B. | 0.80 |
| C. | 0.33 |
| D. | 0.56 |
| Answer» C. 0.33 | |
| 3140. |
In the circuit shown, the symbols have their usual meanings. The cell has emf E. X is initially joined to V for a long time. Then, disjoined to Z The maximum charge on C at any later time will be |
| A. | \[\frac{E}{R\sqrt{LC}}\] |
| B. | \[\frac{ER}{2\sqrt{LC}}\] |
| C. | \[\frac{E\sqrt{LC}}{2R}\] |
| D. | \[\frac{E\sqrt{LC}}{R}\] |
| Answer» E. | |
| 3141. |
For the circuit as shown in figure; the applied Current in A.C. circuit is zero ampere and\[{{I}_{C}}=10A\]. Then the magnitude of current \[{{I}_{L}}\]is |
| A. | 0.166666666666667 |
| B. | 0.416666666666667 |
| C. | 0.208333333333333 |
| D. | undefined |
| Answer» C. 0.208333333333333 | |
| 3142. |
A condenser of capacity C is charged to a potential difference of \[{{V}_{1}}\]. The plates of the condenser are then connected to an ideal inductor of inductance L. The current through the inductor when the potential difference across the condenser reduces to \[{{V}_{2}}\] is |
| A. | \[{{\left( \frac{C(V_{1}^{2}-V_{2}^{2})}{L} \right)}^{1/2}}\] |
| B. | \[{{\left( \frac{C{{({{V}_{1}}-{{V}_{2}})}^{2}}}{L} \right)}^{1/2}}\] |
| C. | \[\frac{C(V_{1}^{2}-V_{2}^{2})}{L}\] |
| D. | \[\frac{C({{V}_{1}}-{{V}_{2}})}{L}\] |
| Answer» B. \[{{\left( \frac{C{{({{V}_{1}}-{{V}_{2}})}^{2}}}{L} \right)}^{1/2}}\] | |
| 3143. |
A resistance 'R' draws power 'P' when connected to an AC source. If an inductance is now placed in series with the resistance, such that the impedance of the circuit becomes 'Z', the power drawn will be |
| A. | \[P\sqrt{\frac{R}{Z}}\] |
| B. | \[P\left( \frac{R}{Z} \right)\] |
| C. | P |
| D. | \[P{{\left( \frac{R}{Z} \right)}^{2}}\] |
| Answer» E. | |
| 3144. |
Find the current passing through battery immediately after key (K) is closed. It is given that initially all the capacitors are uncharged. (given that \[R=6\,\Omega \] and \[C=4\mu F\]) |
| A. | 0.0416666666666667 |
| B. | 0.208333333333333 |
| C. | 0.125 |
| D. | 0.0833333333333333 |
| Answer» B. 0.208333333333333 | |
| 3145. |
A series R-C circuit is connected to an alternating voltage source. Consider two situations: When capacitor is air filled. When capacitor is mica filled. Current through resistor is i and voltage across capacitor is V then: |
| A. | \[{{V}_{a}}>{{V}_{b}}\] |
| B. | \[{{i}_{a}}>{{i}_{b}}\] |
| C. | \[{{V}_{a}}={{V}_{b}}\] |
| D. | \[{{V}_{a}}<{{V}_{b}}\] |
| Answer» B. \[{{i}_{a}}>{{i}_{b}}\] | |
| 3146. |
An inductor 20 mH, a capacitor \[50\,\mu F\]and a resistor \[40\Omega \] are connected in series across a source of emf V=10 sin 340 t. The power loss in A.C. circuit is: |
| A. | 0.51 W |
| B. | 0.67 W |
| C. | 0.76 W |
| D. | 0.89 W |
| Answer» B. 0.67 W | |
| 3147. |
The voltage time (V-t) graph for triangular wave having peak value \[{{V}_{0}}\] is as shown in figure. The rms value of V in time interval from t=0 to T/4 is |
| A. | \[\frac{{{V}_{0}}}{\sqrt{3}}\] |
| B. | \[\frac{{{V}_{0}}}{2}\] |
| C. | \[\frac{{{V}_{0}}}{\sqrt{2}}\] |
| D. | \[\frac{{{V}_{0}}}{3}\] |
| Answer» B. \[\frac{{{V}_{0}}}{2}\] | |
| 3148. |
A coil has resistance 30 ohm and inductive reactance 20 ohm at 50 Hz frequency If an ac source, of 200 volt, 100 Hz, is connected across the coil, the current in the coil will be |
| A. | 4.0 A |
| B. | 8.0 A |
| C. | \[\frac{20}{\sqrt{13}}\,A\] |
| D. | 2.0 A |
| Answer» B. 8.0 A | |
| 3149. |
An ac voltage is applied to a resistance R and an inductor L in series. If R and the inductive reactance are both equal to \[3\,\Omega \], the phase difference between the applied voltage and the current in the circuit is |
| A. | \[\pi /6\] |
| B. | \[\pi /4\] |
| C. | \[\pi /2\] |
| D. | zero |
| Answer» C. \[\pi /2\] | |
| 3150. |
The equation of alternating current is : \[I=50\sqrt{2}\,\sin \,400\pi t\,amp\]. Then the frequency and root mean square of current are respectively |
| A. | \[200\text{ }Hz,\text{ }50\text{ }amp\] |
| B. | \[400\pi \,Hz,\,\,50\sqrt{2}\,\,\,amp\] |
| C. | \[200\,Hz,\,\,\,50\sqrt{2}\,\,amp\] |
| D. | \[50\text{ }Hz,\text{ }200\text{ }amp\] |
| Answer» B. \[400\pi \,Hz,\,\,50\sqrt{2}\,\,\,amp\] | |