Alternating Current

A transformer consisting of 300 turns in the primary and 150 turns in the secondary gives output power of 2.2 kW. If the current in the secondary coil is 10A, then the input voltage and current in the primary coil are :

A resistance of 40 $\Omega$ is connected to a source of alternating current rated 220 V, 50 Hz. Find the time taken by the current to change from its maximum value to the rms value :

Match List - I with List - II : .tg {border-collapse:collapse;border-spacing:0;} .tg td{border-color:black;border-style:solid;border-width:1px;font-family:Arial, sans-serif;font-size:14px; overflow:hidden;padding:10px 5px;word-break:normal;} .tg th{border-color:black;border-style:solid;border-width:1px;font-family:Arial, sans-serif;font-size:14px; font-weight:normal;overflow:hidden;padding:10px 5px;word-break:normal;} .tg .tg-amwm{font-weight:bold;text-align:center;vertical-align:top} .tg .tg-0lax{text-align:left;vertical-align:top} List I List II A. AC generator I. Presence of both L and C B. Transformer II. Electromagnetic Induction C. Resonance phenomenon to occur III. Quality factor D. Sharpness of resonance IV. Mutual Induction Choose the correct answer from the options given below :

Primary side of a transformer is connected to $230 \mathrm{~V}, 50 \mathrm{~Hz}$ supply. Turns ratio of primary to secondary winding is $10: 1$. Load resistance connected to secondary side is $46 \Omega$. The power consumed in it is :

A series LCR circuit driven by 300 V at a frequency of 50 Hz contains a resistance R = 3 k$\Omega$, an inductor of inductive reactance X_L = 250 $\pi$$\Omega$ and an unknown capacitor. The value of capacitance to maximize the average power should be : (Take $\pi$² = 10)

An inductance coil has a reactance of 100 $\Omega$. When an AC signal of frequency 1000 Hz is applied to the coil, the applied voltage leads the current by 45^o. The self-inductance of the coil is

A 0.07 H inductor and a 12$\Omega$ resistor are connected in series to a 220V, 50 Hz ac source. The approximate current in the circuit and the phase angle between current and source voltage are respectively. [Take $\pi$ as ${{22} \over 7}$]

A 100$\Omega$ resistance, a 0.1 $\mu$F capacitor and an inductor are connected in series across a 250 V supply at variable frequency. Calculate the value of inductance of inductor at which resonance will occur. Given that the resonant frequency is 60 Hz.

A sinusoidal voltage V(t) = 210 sin 3000 t volt is applied to a series LCR circuit in which L = 10 mH, C = 25 $\mu$F and R = 100 $\Omega$. The phase difference ($\Phi$) between the applied voltage and resultant current will be :

The power factor of $AC$ circuit having resistance $(R)$ and inductance $(L)$ connected in series and an angular velocity $\omega$ is

In an $LCR$ series $a.c.$ circuit, the voltage across each of the components, $L,C$ and $R$ is $50V$. The voltage across the $L.C$ combination will be :

In a $LCR$ circuit capacitance is changed from $C$ to $2$ $C$. For the resonant frequency to remain unchaged, the inductance should be changed from $L$ to

Alternating current can not be measured by $D.C.$ ammeter because

The self inductance of the motor of an electric fan is $10$ $H$. In order to impart maximum power at $50$ $Hz$, it should be connected to a capacitance of

A circuit has a resistance of $12$ $ohm$ and an impedance of $15$ $ohm$. The power factor of the circuit will be

The phase difference between the alternating current and $emf$ is ${\pi \over 2}.$ Which of the following cannot be the constituent of the circuit?

In a series resonant $LCR$ circuit, the voltage across $R$ is $100$ volts and $R = 1\,k\Omega$ with $C = 2\mu F.$ The resonant frequency $\omega$ is $200$ $rad/s$. At resonance the voltage across $L$ is

In an $a.c.$ circuit the voltage applied is $E = {E_0}\,\sin \,\omega t.$ The resulting current in the circuit is $I = {I_0}\sin \left( {\omega t - {\pi \over 2}} \right).$ The power consumption in the circuit is given by

In an ac circuit, an inductor, a capacitor and a resistor are connected in series with X_L = R = X_C. Impedance of this circuit is :