## 1. What differentiates Alternating Current (AC) from Direct Current (DC)?

### Answer:

### Explanation:

The primary difference is that AC changes its direction periodically while DC flows in a constant direction.

## 2. The standard frequency of AC in most countries is:

### Answer:

### Explanation:

In most countries, the standard frequency of AC is 50 Hz, though some, like the USA, use 60 Hz.

## 3. The average value of AC over one complete cycle is:

### Answer:

### Explanation:

Over one complete cycle, the positive half cancels out the negative half, resulting in an average value of zero.

## 4. The effective or RMS value of an AC is:

### Answer:

### Explanation:

RMS (Root Mean Square) value is approximately 0.707 times the peak value for a sinusoidal AC.

## 5. In a purely resistive AC circuit, the phase difference between current and voltage is:

### Answer:

### Explanation:

In a purely resistive circuit, the current and voltage are in phase, resulting in a phase difference of 0 degrees.

## 6. In an AC circuit with only capacitance, the current leads the voltage by:

### Answer:

### Explanation:

In a purely capacitive circuit, the current leads the voltage by a phase difference of 90 degrees.

## 7. Which device allows AC to pass but blocks DC?

### Answer:

### Explanation:

A capacitor blocks DC and allows AC to pass through.

## 8. The impedance in an LCR circuit is given by:

### Answer:

### Explanation:

Impedance, Z, in an LCR circuit is given by Z = √(R^2 + (XL – XC)^2).

## 9. In an AC circuit with only inductance, the voltage leads the current by:

### Answer:

### Explanation:

In a purely inductive circuit, the voltage leads the current by a phase difference of 90 degrees.

## 10. Power factor in an AC circuit is defined as:

### Answer:

### Explanation:

Power factor is the cosine of the phase difference, defined as the ratio of resistance to impedance, i.e., cos(Φ) = R/Z.

## 11. The power consumed in a purely capacitive circuit is:

### Answer:

### Explanation:

In a purely capacitive circuit, the power consumed is zero as the phase difference between current and voltage is 90 degrees.

## 12. In a series LCR circuit at resonance, the impedance is:

### Answer:

### Explanation:

At resonance in a series LCR circuit, XL = XC, so impedance Z equals the resistance R.

## 13. Resonance in an AC circuit means:

### Answer:

### Explanation:

At resonance, the impedance is minimum, and current is maximum in a series LCR circuit.

## 14. The unit of reactance is:

### Answer:

### Explanation:

Reactance (both capacitive and inductive) is measured in Ohms.

## 15. Which of the following is not a type of transformer?

### Answer:

### Explanation:

There's no such thing as a 'step-side' transformer. Common types include step-up, step-down, and power transformers.

## 16. In an AC generator, the produced EMF is directly proportional to:

### Answer:

### Explanation:

The induced EMF in an AC generator is directly proportional to the speed of rotation and the number of turns in the coil.

## 17. In a pure inductance, the power factor is:

### Answer:

### Explanation:

For a purely inductive circuit, the power factor is zero, as the phase difference between current and voltage is 90 degrees.

## 18. In a transformer, the number of turns in the primary coil compared to the secondary coil determines:

### Answer:

### Explanation:

In a transformer, the ratio of the number of turns in the primary coil to the secondary coil determines whether the voltage is stepped up or stepped down.

## 19. The phenomenon of a current in the primary coil inducing a current in the secondary coil without any direct connection is called:

### Answer:

### Explanation:

Mutual induction is the phenomenon where a change in current in one coil induces a voltage in a nearby coil.

## 20. Choke in a tube light is essentially a:

### Answer:

### Explanation:

The choke in a tube light is essentially an inductor used to regulate the current in the circuit.