Physics
Q. In a thin film interference experiment, what type of interference occurs when light reflects off a denser medium? (2023)
A.
Constructive interference
B.
Destructive interference
C.
No interference
D.
Total internal reflection
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Solution
When light reflects off a denser medium, a phase change of π occurs, leading to destructive interference for certain path differences.
Correct Answer: B — Destructive interference
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Q. In a thin film of oil on water, what color will be seen if the film thickness is such that destructive interference occurs for blue light? (2021)
A.
Red
B.
Green
C.
Blue
D.
Yellow
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Solution
If destructive interference occurs for blue light, the color seen will be the complementary color, which is red.
Correct Answer: A — Red
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Q. In a thin film of oil on water, which color will appear at the center of the pattern if the film thickness is such that it causes constructive interference for red light? (2022)
A.
Red
B.
Blue
C.
Green
D.
Yellow
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Solution
The color that appears at the center of the pattern corresponds to the wavelength that experiences constructive interference, which in this case is red light.
Correct Answer: A — Red
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Q. In a thin film of oil on water, which color will appear at the center of the pattern if the film is viewed in white light? (2022)
A.
Red
B.
Blue
C.
Green
D.
Yellow
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Solution
At the center of the thin film interference pattern, the color that appears is typically green due to the constructive interference of wavelengths in that range.
Correct Answer: C — Green
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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 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 0.8, 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
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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
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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 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 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 voltage is given by V(t) = V0 sin(ωt). What is the peak voltage if V0 = 10V? (2021)
A.
5V
B.
10V
C.
15V
D.
20V
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Solution
The peak voltage V0 is given directly in the equation as 10V.
Correct Answer: B — 10V
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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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Q. In an adiabatic process, the temperature of an ideal gas decreases. What happens to its pressure?
A.
Increases
B.
Decreases
C.
Remains constant
D.
Depends on volume
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Solution
In an adiabatic process, as the temperature decreases, the pressure also decreases due to the ideal gas law.
Correct Answer: B — Decreases
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Q. In an isochoric process, which of the following remains constant? (2022)
A.
Pressure
B.
Volume
C.
Temperature
D.
Internal Energy
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Solution
In an isochoric process, the volume remains constant.
Correct Answer: B — Volume
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Q. In an RLC circuit, if the resistance is 6Ω, inductive reactance is 8Ω, and capacitive reactance is 4Ω, what is the total impedance? (2021)
A.
10Ω
B.
12Ω
C.
14Ω
D.
16Ω
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Solution
Total impedance Z = √(R² + (XL - XC)²) = √(6² + (8 - 4)²) = √(36 + 16) = √52 ≈ 10Ω.
Correct Answer: B — 12Ω
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Q. In an RLC circuit, if the resistance is increased, what happens to the quality factor (Q)? (2021)
A.
Increases
B.
Decreases
C.
Remains the same
D.
Becomes zero
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Solution
The quality factor Q is inversely proportional to resistance. Increasing resistance decreases Q.
Correct Answer: B — Decreases
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Q. In an RLC series circuit, if the inductive reactance is greater than the capacitive reactance, the circuit is said to be: (2022)
A.
Resonant
B.
Inductive
C.
Capacitive
D.
Purely resistive
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Solution
If the inductive reactance (XL) is greater than the capacitive reactance (XC), the circuit is inductive.
Correct Answer: B — Inductive
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Q. In an RLC series circuit, if the resistance is 10 Ω, inductance is 0.1 H, and capacitance is 100 μF, what is the resonant frequency? (2023)
A.
50 Hz
B.
100 Hz
C.
159 Hz
D.
200 Hz
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Solution
The resonant frequency f0 = 1/(2π√(LC)) = 1/(2π√(0.1 * 100e-6)) = 159 Hz.
Correct Answer: C — 159 Hz
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Q. In an RLC series circuit, if the total impedance is 20Ω and the resistance is 15Ω, what is the inductive reactance? (2022)
A.
5Ω
B.
10Ω
C.
15Ω
D.
20Ω
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Solution
Using Z = √(R² + (XL)²), solve for XL.
Correct Answer: A — 5Ω
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Q. In an RLC series circuit, if the total impedance is 20Ω and the resistance is 15Ω, what is the reactance? (2022)
A.
5Ω
B.
10Ω
C.
15Ω
D.
20Ω
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Solution
Using Z = √(R² + X²), we find X = √(Z² - R²). Here, Z = 20Ω, R = 15Ω.
Correct Answer: A — 5Ω
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Q. In an RLC series circuit, if the total impedance is 50 ohms and the resistance is 30 ohms, what is the reactance? (2020)
A.
40 ohms
B.
30 ohms
C.
20 ohms
D.
10 ohms
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Solution
Using Z = √(R² + X²), we find X = √(Z² - R²) = √(50² - 30²) = √(2500 - 900) = √1600 = 40 ohms.
Correct Answer: A — 40 ohms
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