Secondary Winding

Q.

A 60 μF capacitor is connected to a 110 V, 60 Hz ac supply. Determine the rms value of the current in the circuit.

Q.

The electric potential decreases uniformly from $120V$ to $80V$ as one move on the x-axis from $x=-1cm$ to $x=+1cm$. The electric field at the origin?

Q.

The electric potential V at any point in space is given V=20x3 volt, where x is in meter. Calculate the electric intensity at point P(1, 0, 2).

Q. $2000\text{V}-200\text{V},20\text{kVA}$ transformers have $66$ turns in the secondary winding. If $I_P$ and $I_S$ represents primary and secondary full-load current respectively, then : (Neglect the power losses in the transformer)

1. $I_P=10\text{A}$
2. $I_P=5\text{A}$
3. $I_S=50\text{A}$
4. $I_S=100\text{A}$

Q.

The current passing through the choke coil of 14 H is decreasing at the rate of 0.32 ampere per second. The e.m.f developed across the coil is

1. 44.8 V

2. 4.48 V

3. 4.5 V

4. 4 V

Q. The electric potential decreases uniformly from 100V to 50V as one moves along the x-axis from x=0 to x=5m.The electric field at x=2m must be equal to 10V/m.Is this statement true or false.

Q. A voltmeter of full scale deflection 10 volt has grading as 10000 ohm/V. What is done to convert it for 25 V at full scale deflection? Find the new grading of the meter.

Q.

1 ohm is equal to

1. 1 volt per ampere

2. 1 ampere per volt

3. 1 ampere per millivolt

4. 1 milliampere per volt

Q. In a step up transformer the turn ratio is $1:3.$ A Daniel cell of emf $1.5\text{V}$ is connected across the primary, the voltage across the secondary is-

1. $13.5\text{V}$
2. $4.5\text{V}$
3. $7.5\text{V}$
4. $0\text{V}$

Q.

Calculate the phase difference between voltage and current, when R = 200 Ohms, L = 1

H, . v = 200/2πHz

1. 0 degrees

2. 60 degrees

3. 90 degrees

4. 45 degrees

Q.

Figure 3.33 shows a potentiometer with a cell of 2.0 V and internal resistance 0.40 Ω maintaining a potential drop across the resistor wire AB. A standard cell which maintains a constant emf of 1.02 V (for very moderate currents up to a few mA) gives a balance point at 67.3 cm length of the wire. To ensure very low currents drawn from the standard cell, a very high resistance of 600 kΩ is put in series with it, which is shorted close to the balance point. The standard cell is then replaced by a cell of unknown emf ε and the balance point found similarly, turns out to be at 82.3 cm length of the wire.

(a) What is the value ε ?

(b) What purpose does the high resistance of 600 kΩ have?

(c) Is the balance point affected by this high resistance?

(d) Is the balance point affected by the internal resistance of the driver cell?

(e) Would the method work in the above situation if the driver cell of the potentiometer had an emf of 1.0 V instead of 2.0 V?

(f ) Would the circuit work well for determining an extremely small emf, say of the order of a few mV (such as the typical emf of a thermo-couple)? If not, how will you modify the circuit?

Q. A coil of resistance 40 Ω is connected across a 4.0 V battery. 0.10 s after the battery is connected, the current in the coil is 63 mA. Find the inductance of the coil.

Q. Match List I with List II.

List I	List II
$a.$ Rectifier $b.$ Stabilizer $c.$ Transformer $d.$ Filter	$i.$ Used either for stepping up or stepping down the A.C. Voltage. $ii.$ Used to convert A.C. voltage into D.C. voltage. $iii.$ Used to remove any ripple in the rectified output voltage. $iv.$ Used for constant output voltage even when the input voltage or load current change.

Choose the correct answer from the options given below:

1. $\left(a\right)-\left(ii\right),\left(b\right)-\left(i\right),\left(c\right)-\left(iv\right),\left(d\right)-\left(iii\right)$
2. $\left(a\right)-\left(ii\right),\left(b\right)-\left(iv\right),\left(c\right)-\left(i\right),\left(d\right)-\left(iii\right)$
3. $\left(a\right)-\left(ii\right),\left(b\right)-\left(i\right),\left(c\right)-\left(iii\right),\left(d\right)-\left(iv\right)$
4. $\left(a\right)-\left(iii\right),\left(b\right)-\left(iv\right),\left(c\right)-\left(i\right),\left(d\right)-\left(ii\right)$

Q. The power delivered in the plate circular of a diode is 1.0 W when the plate voltage is 36 V. Find the power delivered if the plate voltage is increased to 49 V. Assume Langmuir-Child equation to hold.

Q.

Calculate the load current and load voltage in the following transformer circuit. Soyrce : 30v AC, Np = 100, Ns =100, Rs =100 Ω

1. 5V, 0.35 A

2. 10V, 0.7 A

3. 6V, 0.3 A

4. 12V, 0.6 A

Q. The current in a conductor and the potential difference across its ends are measured by an ammeter and a voltmeter. The meters draw negligible currents. The ammeter is accurate but the voltmeter has a zero error (that is, it does not read zero when no potential difference is applied). Calculate the zero error if the readings for two different conditions are 1.75 A, 14.4 V and 2.75 A, 22.4 V.

Q. An average emf of 20 V is induced in an inductor when the current in it is changed from 2.5 A in one direction to the same value in the opposite direction in 0.1 s. Find the self-inductance of the inductor.

Q.

A storage battery of e.m.f. $8V$ and internal resistance $0.5$$\Omega$ is being charged by a $120V$ supply using a series resistor of $15.5$$\Omega$. The terminal voltage of battery during charging is

1. $120V$

2. $8.5V$

3. $11.5V$

4. $3.5V$

Q.

Calculate the load current and load voltage in the following transformer circuit. Soyrce : 30v AC, Np = 100, Ns =100, Rs =100 Ω

1. 5V, 0.35 A

2. 10V, 0.7 A

3. 6V, 0.3 A

4. 12V, 0.6 A

Q.

Calculate the load current and load voltage in the following transformer circuit. Soyrce : 30v AC, Np = 100, Ns =100, Rs =100 Ω

1. 5V, 0.35 A

2. 10V, 0.7 A

3. 6V, 0.3 A

4. 12V, 0.6 A

Q.

Calculate the load current and load voltage in the following transformer circuit. Soyrce : 30v AC, Np = 100, Ns =100, Rs =100 Ω

1. 5V, 0.35 A

2. 10V, 0.7 A

3. 6V, 0.3 A

4. 12V, 0.6 A

Q. Consider the situation of the previous problem. Define displacement resistance R_d = V/i_d of the space between the plates, where V is the potential difference between the plates and i_d is the displacement current. Show that R_d varies with time as $R_d=R(e^{t/\tau }-1)$.

Q. Solve this:
Q. In a R-L circuit discharging current is given by $I=I_0{e}^{\raisebox{1ex}{$-t$}\!\left/ \!\raisebox{-1ex}{$\tau $}\right.}$, where $\tau$ is the time constant of the circuit. The average current for the period t = 0 to t = $\tau$ is

Q.

How is potentiometer superior than voltmeter

Q. The dynamic plate resistance of a triode value is 10 kΩ. Find the change in the plate current if the plate voltage is changed from 200 V to 220 V.

Q. Find the current measured by the ammeter in the circuit shown in the figure (32-E18).

Q. A shunt resistance 20 ohm is connected across a galvanometer in parallel, and the combination is connected to a cell of emf E through a resistance of 40 ohm. the ratio of potential difference across the shunt to that of the resistor is 1:3. what is the resistance of the galvanometer?