
An AC ammeter is used to measure the current in a circuit. When a given direct current passes through the circuit, the AC ammeter reads \(6~\text A.\) When another alternating current passes through the circuit, the AC ammeter reads \(8~\text A.\) Then the reading of this ammeter if DC and AC flow through the circuit simultaneously is:
1. \(10 \sqrt{2}~\text A\)
2. \(14~\text A\)
3. \(10~\text A\)
4. \(15~\text A\)
A direct current of \(5~ A\) is superimposed on an alternating current \(I=10sin ~\omega t\) flowing through a wire. The effective value of the resulting current will be:
| 1. | \(15/2~A\) | 2. | \(5 \sqrt{3}~A\) |
| 3. | \(5 \sqrt{5}~A\) | 4. | \(15~A\) |
An ideal resistance \(R,\) ideal inductance \(L,\) ideal capacitance \(C,\) and AC voltmeters \(V_1, V_2, V_3~\text{and}~V_4 \)

| 1. | reading in \(V_3\) = reading in \(V_1\) |
| 2. | reading in \(V_1\) = reading in \(V_2\) |
| 3. | reading in \(V_2\) = reading in \(V_4\) |
| 4. | reading in \(V_2\) = reading in \(V_3\) |
| 1. | \(50\) V | 2. | \(50 \sqrt{2} ~\text{V}\) |
| 3. | \(100\) V | 4. | \(0\) V |
An AC voltage source is connected to a series \(LCR\) circuit. When \(L\) is removed from the circuit, the phase difference between current and voltage is \(\dfrac{\pi}{3}\). If \(C\) is instead removed from the circuit, the phase difference is again \(\dfrac{\pi}{3}\) between current and voltage. The power factor of the circuit is:
1. \(0.5\)
2. \(1.0\)
3. \(-1.0\)
4. zero
The circuit is in a steady state when the key is at position \(1\). If the switch is changed from position \(1\) to position \(2\), then the steady current in the circuit will be:
| 1. | \(E_o \over R\) | 2. | \(E_o \over 3R\) |
| 3. | \(E_o \over 2R\) | 4. | \(E_o \over 4R\) |
| 1. | \(2500\) W | 2. | \(250\) W |
| 3. | \(5000\) W | 4. | \(4000\) W |
In a box \(Z\) of unknown elements (\(L\) or \(R\) or any other combination), an ac voltage \(E = E_0 \sin(\omega t + \phi)\) is applied and the current in the circuit is found to be \(I = I_0 \sin\left(\omega t + \phi +\frac{\pi}{4}\right)\). The unknown elements in the box could be:

| 1. | Only the capacitor |
| 2. | Inductor and resistor both |
| 3. | Either capacitor, resistor, and an inductor or only capacitor and resistor |
| 4. | Only the resistor |
| 1. | \(V_r=V_L>V_C\) |
| 2. | \(V_R \neq V_L=V_C\) |
| 3. | \(V_R \neq V_L \neq V_C\) |
| 4. | \(V_R=V_C \neq V_L\) |