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Physics > AC CIRCUIT > Flashcards

AC CIRCUIT Flashcards

1
Q

What does AC stand for in electrical circuits?

A

Alternating Current

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2
Q

True or False: In an AC circuit, the current flows in one direction only.

A

False

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3
Q

Fill in the blank: The frequency of AC is measured in _____?

A

Hertz (Hz)

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4
Q

What is the typical frequency of AC in household circuits in most countries?

A

50 or 60 Hz

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5
Q

What is the peak voltage in an AC circuit?

A

The maximum voltage reached in one cycle

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6
Q

What is the root mean square (RMS) voltage in an AC circuit?

A

The effective voltage that delivers the same power as a DC circuit

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7
Q

True or False: The RMS value of an AC voltage is always greater than the peak voltage.

A

False

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8
Q

What is the formula to calculate RMS voltage from peak voltage?

A

V_rms = V_peak / √2

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9
Q

What component is used to store energy in an AC circuit?

A

Capacitor

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10
Q

What is the role of an inductor in an AC circuit?

A

To store energy in a magnetic field

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11
Q

Fill in the blank: The total opposition to current flow in an AC circuit is called _____?

A

Impedance

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12
Q

What is the unit of impedance?

A

Ohm (Ω)

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13
Q

How is impedance in an AC circuit different from resistance in a DC circuit?

A

Impedance accounts for both resistance and reactance.

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14
Q

What is reactance?

A

The opposition to AC due to capacitance or inductance

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15
Q

True or False: Capacitive reactance decreases with increasing frequency.

A

True

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16
Q

What is the formula for capacitive reactance (Xc)?

A

Xc = 1 / (2πfC)

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17
Q

What happens to the current in a capacitive circuit when the frequency increases?

A

The current increases.

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18
Q

What is inductive reactance (Xl)?

A

The opposition to current flow due to inductance in an AC circuit

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19
Q

What is the formula for inductive reactance (Xl)?

A

Xl = 2πfL

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20
Q

True or False: Inductive reactance increases with increasing frequency.

A

True

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21
Q

What is the phase difference in an AC circuit?

A

The angle by which the current and voltage waveforms are out of sync

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22
Q

In a purely resistive AC circuit, what is the phase difference between voltage and current?

A

0 degrees

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23
Q

In a purely inductive AC circuit, what is the phase difference between voltage and current?

A

90 degrees

24
Q

In a purely capacitive AC circuit, what is the phase difference between voltage and current?

A

-90 degrees

25
Q

What is the power factor in an AC circuit?

A

The ratio of real power to apparent power

26
Q

What is the range of power factor values?

27
Q

True or False: A power factor of 1 indicates all the power is being used effectively.

28
Q

What is the formula for calculating real power (P) in an AC circuit?

A

P = V_rms * I_rms * cos(φ)

29
Q

Fill in the blank: The total power in an AC circuit is known as _____?

A

Apparent Power

30
Q

What is the unit for apparent power?

A

Volt-Ampere (VA)

31
Q

What is the relationship between real power, reactive power, and apparent power known as?

A

Power triangle

32
Q

What is reactive power (Q)?

A

Power that alternates between the source and reactive components without being consumed

33
Q

What is the formula for reactive power?

A

Q = V_rms * I_rms * sin(φ)

34
Q

What is the significance of the resonance frequency in an RLC circuit?

A

It is the frequency at which impedance is minimized and current is maximized.

35
Q

What is the formula for the resonance frequency (f₀) in an RLC circuit?

A

f₀ = 1 / (2π√(LC))

36
Q

True or False: At resonance, the inductive reactance equals the capacitive reactance.

37
Q

What type of circuit is created when a resistor, inductor, and capacitor are connected in series?

A

Series RLC circuit

38
Q

What type of circuit is created when a resistor, inductor, and capacitor are connected in parallel?

A

Parallel RLC circuit

39
Q

What is the effect of adding more resistance to an AC circuit?

A

It reduces the current.

40
Q

What is the effect of adding more capacitance to an AC circuit?

A

It increases the capacitive reactance.

41
Q

What is the effect of adding more inductance to an AC circuit?

A

It increases the inductive reactance.

42
Q

What is a transformer used for in AC circuits?

A

To change the voltage level of AC electricity.

43
Q

True or False: Transformers only work with direct current (DC).

44
Q

What is the principle of operation of a transformer?

A

Electromagnetic induction

45
Q

What are the two main types of transformers?

A

Step-up and step-down transformers

46
Q

What is the purpose of a step-up transformer?

A

To increase voltage while decreasing current.

47
Q

What is the purpose of a step-down transformer?

A

To decrease voltage while increasing current.

48
Q

What is the law of conservation of energy in relation to transformers?

A

The power input equals the power output (ignoring losses).

49
Q

What is the formula relating primary and secondary voltages in a transformer?

A

V₁ / V₂ = N₁ / N₂

50
Q

What does N₁ and N₂ represent in the transformer voltage formula?

A

The number of turns in the primary and secondary coils, respectively.

51
Q

True or False: In an AC circuit, the total current is the sum of the individual branch currents in a parallel circuit.

52
Q

What is the equivalent resistance in a parallel circuit?

A

1 / R_eq = 1 / R₁ + 1 / R₂ + … + 1 / R_n

53
Q

What happens to the total current in a parallel circuit if one branch is removed?

A

The total current will still flow through the remaining branches.

54
Q

What is the primary use of an oscilloscope in AC circuit analysis?

A

To visualize voltage waveforms.

55
Q

What is the significance of the waveform shape in AC circuits?

A

It affects the power and behavior of the circuit.

Physics (1 decks)

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