The primary and secondary coils of an ideal transformer have 100 and 5000 turns respectively. The magnetic flux linking the primary coil is given by $\varphi$= 20t + 10. The output voltage across the secondary coil is

1. 20 V

2. 500 V

3. 1000 V

4. 10000 V

In the LCR-circuit shown below, if the reading of the voltmeters $V_{1<mspace\; width="1em"></mspace>}$and $V_2$ are same, then

1. ${\omega }^2=\frac{1}{LC}$

2. Reading of the voltmeter V is 50 V

3. Reading of the ammeter A is 5 A

4. All of these

If \(R\) and \(L\) are resistance and inductance of a choke coil and \(f\) is the frequency of current through it, then the average power of the choke coil is proportional to:
1. \(R ~\)
2. \(\frac{1}{f^2}\)
3. \(\frac{1}{L^2}\)
4. All of these

Which of the following is/are copper loss/losses in a transformer?

1. Hysteresis loss

2. Eddy current loss

3. Heat loss in the primary and second coils

4. Both (1) & (2)

Half power frequencies for the circuit shown below are 200rad/s and 800 rad/s. The value of the product LC is $(is<mspace\; width="1em"></mspace>secon{d}^2/radia{n}^2)$

$1.<mspace\; width="1em"></mspace>6.25<mspace\; width="1em"></mspace>\times {10}^{-3}$
$2.<mspace\; width="1em"></mspace>6.25\times {10}^{-6}$
$3.<mspace\; width="1em"></mspace>1.25\times {10}^{-3}$
$4.<mspace\; width="1em"></mspace>1.25\times {10}^{-5}$

The power factor of the given circuit is:
             

In LC oscillation, what is the current in the circuit when the total energy is stored in the form of magnetic energy?
(q₀ is the maximum charge stored by the capacitor)

$1.$ $Zero$ $$
$2.$ $\frac{q_0}{\sqrt{Lc}}$ $$
$3.$ $\frac{q_0}{LC}$ $$
$4.$ $q_0\sqrt{LC}$

The variation of alternating current (l) with time (t) is shown in the given graph. The average value of current for half cycle is:
         

$1.<mspace\; width="1em"></mspace>\frac{2{/}_0}{\pi }$
$2.<mspace\; width="1em"></mspace>\frac{l_0}{\sqrt{2}}$
$3.<mspace\; width="1em"></mspace>\frac{l_0}{2}$
$4.<mspace\; width="1em"></mspace>Zero<mspace\; width="1em"></mspace>$

A capacitor and a resistor are connected in series across a.c. supply. Which of the following phasor diagram may be correct?

1.

2.

3.

4.