Q. In a uniform magnetic field, the magnetic force on a current-carrying conductor is maximum when the angle between the conductor and the field is: (2019)
A.
0 degrees
B.
90 degrees
C.
45 degrees
D.
180 degrees
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Solution
The magnetic force is maximum when the angle between the conductor and the magnetic field is 90 degrees, as sin(90°) = 1.
Correct Answer: B — 90 degrees
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Q. In a vacuum, which of the following travels the fastest?
A.
Sound
B.
Light
C.
Water waves
D.
Radio waves
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Solution
In a vacuum, light travels the fastest at approximately 3 x 10^8 m/s, while sound and water waves require a medium to travel.
Correct Answer: B — Light
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Q. In a Zener diode, what is the purpose of the reverse breakdown region? (2020)
A.
To increase voltage
B.
To regulate voltage
C.
To decrease current
D.
To store energy
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Solution
The reverse breakdown region in a Zener diode allows it to regulate voltage by maintaining a constant output voltage.
Correct Answer: B — To regulate voltage
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Q. In a zero-order reaction, the rate of reaction is independent of the concentration of the reactants. What is the unit of the rate constant (k) for a zero-order reaction? (2023)
A.
mol/L·s
B.
L^2/mol·s
C.
mol/L
D.
s^-1
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Solution
For a zero-order reaction, the rate is constant and does not depend on the concentration of reactants. The unit of the rate constant (k) is mol/L·s.
Correct Answer: A — mol/L·s
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Q. In a zero-order reaction, the rate of reaction is independent of which of the following? (2023) 2023
A.
Concentration of reactants
B.
Temperature
C.
Presence of a catalyst
D.
All of the above
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Solution
In a zero-order reaction, the rate is constant and does not depend on the concentration of the reactants.
Correct Answer: A — Concentration of reactants
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Q. In an AC circuit, if the current is given by I(t) = I0 cos(ωt), what is the RMS current? (2021)
A.
I0/√2
B.
I0
C.
2I0
D.
I0/2
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Solution
The RMS value of a cosine function is I0/√2.
Correct Answer: A — I0/√2
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Q. In an AC circuit, if the current lags the voltage by 30 degrees, what is the power factor? (2023)
A.
0.866
B.
0.5
C.
1
D.
0.707
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Solution
The power factor (PF) is given by cos(θ). If θ = 30 degrees, PF = cos(30°) = √3/2 ≈ 0.866.
Correct Answer: A — 0.866
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Q. In an AC circuit, if the frequency is 60Hz and the inductance is 0.2H, what is the inductive reactance? (2021)
A.
12.56Ω
B.
37.68Ω
C.
75.36Ω
D.
100Ω
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Solution
Inductive reactance (XL) = 2πfL = 2π(60)(0.2) ≈ 75.36Ω.
Correct Answer: B — 37.68Ω
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Q. In an AC circuit, if the frequency is increased, what happens to the inductive reactance? (2020)
A.
It increases
B.
It decreases
C.
It remains constant
D.
It becomes zero
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Solution
Inductive reactance (XL = 2πfL) increases with an increase in frequency.
Correct Answer: A — It increases
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Q. In an AC circuit, if the power factor is 0.5, what is the angle φ between the voltage and current? (2019)
A.
30 degrees
B.
60 degrees
C.
90 degrees
D.
45 degrees
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Solution
The power factor (cosφ) is 0.5, which corresponds to an angle φ of 60 degrees.
Correct Answer: B — 60 degrees
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Q. In an AC circuit, if the power factor is 0.8, what is the angle between the voltage and current? (2020)
A.
36.87°
B.
53.13°
C.
60°
D.
45°
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Solution
The angle θ can be found using cos(θ) = power factor. Therefore, θ = cos⁻¹(0.8) ≈ 36.87°.
Correct Answer: B — 53.13°
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Q. In an AC circuit, if the resistance is 10 ohms and the inductive reactance is 20 ohms, what is the impedance? (2020)
A.
10 ohms
B.
20 ohms
C.
√(10² + 20²)
D.
30 ohms
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Solution
The impedance Z = √(R² + XL²) = √(10² + 20²) = √(100 + 400) = √500 = 22.36 ohms.
Correct Answer: C — √(10² + 20²)
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Q. In an AC circuit, if the resistance is 10 ohms and the inductive reactance is 20 ohms, what is the total impedance? (2020)
A.
10 ohms
B.
20 ohms
C.
√(10² + 20²)
D.
30 ohms
Show solution
Solution
The total impedance Z = √(R² + XL²) = √(10² + 20²) = √(100 + 400) = √500 = 22.36 ohms.
Correct Answer: C — √(10² + 20²)
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Q. In an AC circuit, if the resistance is 10Ω and the inductive reactance is 20Ω, what is the total impedance? (2020)
A.
10Ω
B.
20Ω
C.
√(10² + 20²)
D.
30Ω
Show solution
Solution
The total impedance Z = √(R² + XL²) = √(10² + 20²) = √(100 + 400) = √500 = 22.36Ω.
Correct Answer: C — √(10² + 20²)
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Q. In an AC circuit, if the total current is 5A and the total voltage is 100V, what is the impedance? (2021)
A.
20Ω
B.
25Ω
C.
30Ω
D.
15Ω
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Solution
Impedance Z = V/I = 100V/5A = 20Ω.
Correct Answer: B — 25Ω
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Q. In an AC circuit, if the voltage is 120 V and the current is 10 A with a power factor of 0.8, what is the real power consumed? (2021)
A.
960 W
B.
1200 W
C.
800 W
D.
1000 W
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Solution
Real power P = V * I * power factor = 120 * 10 * 0.8 = 960 W.
Correct Answer: A — 960 W
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Q. In an AC circuit, if the voltage is 120 V and the current is 10 A, what is the power factor if the real power is 600 W? (2021)
A.
0.5
B.
0.6
C.
0.8
D.
1.0
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Solution
Power factor = Real Power / (Voltage × Current) = 600 / (120 × 10) = 0.5.
Correct Answer: C — 0.8
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Q. In an AC circuit, if the voltage is 120V and the current is 10A with a power factor of 0.8, what is the real power consumed? (2021)
A.
120W
B.
800W
C.
960W
D.
1000W
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Solution
Real power P = V * I * power factor = 120V * 10A * 0.8 = 960W.
Correct Answer: C — 960W
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Q. In an AC circuit, if the voltage is 120V and the current is 10A, what is the power factor if the real power is 600W? (2022)
A.
0.5
B.
0.6
C.
0.8
D.
1.0
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Solution
Power factor = Real Power / (Voltage x Current) = 600 / (120 x 10) = 600 / 1200 = 0.5.
Correct Answer: B — 0.6
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Q. In an AC circuit, if the voltage is given by V(t) = 100 sin(100t), what is the RMS voltage? (2023)
A.
100 V
B.
70.7 V
C.
50 V
D.
141.4 V
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Solution
The RMS voltage is V_rms = V0/√2 = 100/√2 = 70.7 V.
Correct Answer: B — 70.7 V
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Q. In an AC circuit, if the voltage is given by V(t) = 100√2 sin(1000t), what is the peak voltage? (2023)
A.
100 V
B.
100√2 V
C.
200 V
D.
50 V
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Solution
The peak voltage is given by the coefficient of sin, which is 100√2.
Correct Answer: B — 100√2 V
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Q. In an AC circuit, if the voltage is given by V(t) = V0 sin(ωt), what is the expression for the current if the circuit is purely inductive? (2023)
A.
I(t) = I0 sin(ωt)
B.
I(t) = I0 sin(ωt - π/2)
C.
I(t) = I0 cos(ωt)
D.
I(t) = I0 cos(ωt + π/2)
Show solution
Solution
In a purely inductive circuit, the current lags the voltage by 90 degrees (π/2 radians). Therefore, I(t) = I0 sin(ωt - π/2).
Correct Answer: B — I(t) = I0 sin(ωt - π/2)
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Q. In an AC circuit, if the voltage is given by V(t) = V_0 sin(ωt), what is the expression for the current if the circuit is purely inductive? (2023)
A.
I(t) = I_0 sin(ωt)
B.
I(t) = I_0 sin(ωt - π/2)
C.
I(t) = I_0 cos(ωt)
D.
I(t) = I_0 cos(ωt + π/2)
Show solution
Solution
In a purely inductive circuit, the current lags the voltage by 90 degrees (or π/2 radians). Therefore, I(t) = I_0 sin(ωt - π/2).
Correct Answer: B — I(t) = I_0 sin(ωt - π/2)
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Q. In an AC circuit, if the voltage is given by V(t) = V₀ sin(ωt), what is the expression for the current through a capacitor? (2022)
A.
I(t) = C dV/dt
B.
I(t) = V₀ sin(ωt)
C.
I(t) = V₀ cos(ωt)
D.
I(t) = V₀ sin(ωt)/R
Show solution
Solution
The current through a capacitor is given by I(t) = C dV/dt. For V(t) = V₀ sin(ωt), the current can be derived from this expression.
Correct Answer: A — I(t) = C dV/dt
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Q. In an AC circuit, if the voltage is V(t) = 120 sin(ωt), what is the RMS voltage? (2017)
A.
120 V
B.
60 V
C.
84.85 V
D.
100 V
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Solution
RMS voltage V_rms = V_peak / √2 = 120 / √2 = 84.85 V.
Correct Answer: C — 84.85 V
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Q. In an AC circuit, the average power consumed is given by which formula? (2022)
A.
P = VI
B.
P = VI cos(φ)
C.
P = V²/R
D.
P = I²R
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Solution
The average power (P) consumed in an AC circuit is given by P = VI cos(φ), where φ is the phase angle between voltage and current.
Correct Answer: B — P = VI cos(φ)
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Q. In an AC circuit, the current lags behind the voltage by 90 degrees in which type of circuit? (2020)
A.
Resistive
B.
Inductive
C.
Capacitive
D.
RLC
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Solution
In an inductive circuit, the current lags behind the voltage by 90 degrees.
Correct Answer: B — Inductive
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Q. In an AC circuit, the current lags the voltage by 90 degrees in which of the following components? (2020)
A.
Resistor
B.
Capacitor
C.
Inductor
D.
Transformer
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Solution
In an inductor, the current lags the voltage by 90 degrees.
Correct Answer: C — Inductor
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Q. In an AC circuit, the current lags the voltage by 90 degrees in which type of circuit? (2020)
A.
Resistive
B.
Capacitive
C.
Inductive
D.
RLC
Show solution
Solution
In an inductive circuit, the current lags the voltage by 90 degrees.
Correct Answer: C — Inductive
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Q. In an AC circuit, the voltage is given by V(t) = V0 sin(ωt). What is the peak voltage? (2021)
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Solution
The peak voltage in the equation V(t) = V0 sin(ωt) is V0.
Correct Answer: A — V0
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