Q. What is the power factor of a circuit with a resistance of 30Ω and a reactance of 40Ω? (2023)
A.
0.6
B.
0.75
C.
0.8
D.
1.0
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Solution
Power factor = R/Z where Z = √(R² + X²). Calculate.
Correct Answer: A — 0.6
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Q. What is the power factor of a circuit with a resistance of 4Ω and a reactance of 3Ω? (2021)
A.
0.6
B.
0.8
C.
1.0
D.
0.75
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Solution
Power factor = R/Z = R/√(R² + X²) = 4/√(4² + 3²) = 4/5 = 0.8.
Correct Answer: A — 0.6
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Q. What is the power factor of a circuit with a resistance of 5 ohms and a reactance of 5 ohms? (2022)
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Solution
Power factor = R/Z = 5/√(5² + 5²) = 5/√50 = √2/2.
Correct Answer: D — √2/2
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Q. What is the power factor of a circuit with a resistance of 5Ω and an inductive reactance of 5Ω? (2022)
A.
0.5
B.
0.707
C.
1
D.
0
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Solution
Power factor = R/Z = 5 / √(5² + 5²) = 5 / √50 = 0.707.
Correct Answer: B — 0.707
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Q. What is the power factor of a circuit with a resistance of 6Ω and a reactance of 8Ω? (2022)
A.
0.75
B.
0.8
C.
0.6
D.
1.0
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Solution
Power factor = R/Z = R/√(R² + X²) = 6/√(6² + 8²) = 6/10 = 0.6.
Correct Answer: B — 0.8
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Q. What is the power factor of a circuit with a resistance of 8Ω and a reactance of 6Ω? (2023)
A.
0.5
B.
0.6
C.
0.8
D.
1.0
Show solution
Solution
Power factor = R/Z, where Z = √(R² + X²) = √(8² + 6²) = 10. Thus, PF = 8/10 = 0.8.
Correct Answer: C — 0.8
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Q. What is the power factor of an AC circuit with a phase angle of 60°? (2022)
A.
0.5
B.
0.866
C.
1
D.
0.707
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Solution
The power factor is cos(60°) = 0.5.
Correct Answer: B — 0.866
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Q. What is the power output of a motor that does 1200 J of work in 30 seconds?
A.
20 W
B.
40 W
C.
60 W
D.
80 W
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Solution
Power = Work / Time = 1200 J / 30 s = 40 W.
Correct Answer: C — 60 W
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Q. What is the power output of a motor that does 3000 J of work in 15 seconds?
A.
200 W
B.
300 W
C.
400 W
D.
500 W
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Solution
Power = Work / Time = 3000 J / 15 s = 200 W.
Correct Answer: B — 300 W
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Q. What is the pressure exerted by a force of 100 N over an area of 5 m²? (2023)
A.
20 Pa
B.
25 Pa
C.
15 Pa
D.
30 Pa
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Solution
Pressure (P) = Force/Area = 100 N / 5 m² = 20 Pa.
Correct Answer: B — 25 Pa
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Q. What is the pressure exerted by a force of 200 N acting on an area of 4 m²? (2015)
A.
50 Pa
B.
100 Pa
C.
200 Pa
D.
400 Pa
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Solution
Pressure = Force/Area = 200 N / 4 m² = 50 Pa.
Correct Answer: B — 100 Pa
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Q. What is the principal quantum number of an electron in the ground state of a hydrogen atom? (2022)
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Solution
The ground state of hydrogen corresponds to n = 1.
Correct Answer: B — 1
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Q. What is the relationship between the frequency and the period of a wave? (2021)
A.
Frequency is the square of the period
B.
Period is the reciprocal of frequency
C.
Frequency and period are unrelated
D.
Period is the square root of frequency
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Solution
The period T is the reciprocal of frequency f, given by T = 1/f.
Correct Answer: B — Period is the reciprocal of frequency
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Q. What is the relationship between the units of energy (Joule) and force (Newton)? (2021)
A.
1 J = 1 N·m
B.
1 J = 1 N/m
C.
1 J = 1 m/N
D.
1 J = 1 N^2
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Solution
1 Joule is defined as the work done when a force of one Newton moves an object one meter, hence 1 J = 1 N·m.
Correct Answer: A — 1 J = 1 N·m
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Q. What is the relationship between the wavelength of light and the angle of diffraction in a grating? (2023)
A.
Directly proportional
B.
Inversely proportional
C.
No relationship
D.
Exponential relationship
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Solution
The angle of diffraction is directly proportional to the wavelength of light used in a diffraction grating, as described by the grating equation.
Correct Answer: A — Directly proportional
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Q. What is the relationship between the wavelength of light and the angle of diffraction in a single-slit experiment? (2023)
A.
Directly proportional
B.
Inversely proportional
C.
No relationship
D.
Exponential relationship
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Solution
The angle of diffraction is inversely proportional to the wavelength; as the wavelength increases, the angle of diffraction decreases.
Correct Answer: B — Inversely proportional
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Q. What is the resistance of a circuit if a current of 5A flows through it when a voltage of 25V is applied? (2022)
A.
5Ω
B.
10Ω
C.
15Ω
D.
20Ω
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Solution
Using Ohm's law (R = V/I), R = 25V / 5A = 5Ω.
Correct Answer: B — 10Ω
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Q. What is the SI unit of electric charge? (2020)
A.
Coulomb
B.
Ampere
C.
Volt
D.
Ohm
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Solution
The SI unit of electric charge is Coulomb (C).
Correct Answer: A — Coulomb
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Q. What is the significance of the wave function in quantum mechanics? (2023)
A.
It describes the position of a particle
B.
It gives the probability of finding a particle
C.
It determines the mass of a particle
D.
It is irrelevant
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Solution
The wave function provides the probability distribution of a particle's position.
Correct Answer: B — It gives the probability of finding a particle
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Q. What is the specific heat capacity of a substance if it requires 500 J to raise the temperature of 2 kg of the substance by 5°C? (2021)
A.
20 J/kg°C
B.
50 J/kg°C
C.
100 J/kg°C
D.
200 J/kg°C
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Solution
Specific heat capacity (c) = Q / (m * ΔT) = 500 J / (2 kg * 5°C) = 50 J/kg°C.
Correct Answer: B — 50 J/kg°C
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Q. What is the specific heat capacity of a substance if it requires 500 J to raise the temperature of 2 kg of the substance by 10°C? (2021)
A.
25 J/kg°C
B.
50 J/kg°C
C.
100 J/kg°C
D.
200 J/kg°C
Show solution
Solution
Specific heat capacity (c) = Q / (m * ΔT) = 500 J / (2 kg * 10°C) = 25 J/kg°C.
Correct Answer: B — 50 J/kg°C
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Q. What is the specific heat capacity of a substance if it takes 500 J to raise the temperature of 2 kg of the substance by 5°C? (2021)
A.
20 J/kg°C
B.
50 J/kg°C
C.
100 J/kg°C
D.
200 J/kg°C
Show solution
Solution
Specific heat capacity (c) = Q / (m * ΔT) = 500 J / (2 kg * 5°C) = 50 J/kg°C
Correct Answer: B — 50 J/kg°C
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Q. What is the specific heat capacity of water if it takes 4200 J to raise the temperature of 1 kg of water by 1°C? (2021)
A.
2100 J/kg°C
B.
4200 J/kg°C
C.
8400 J/kg°C
D.
1000 J/kg°C
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Solution
The specific heat capacity of water is defined as the amount of heat required to raise the temperature of 1 kg of water by 1°C, which is given as 4200 J/kg°C.
Correct Answer: B — 4200 J/kg°C
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Q. What is the speed of light in vacuum? (2020)
A.
3 x 10^8 m/s
B.
3 x 10^6 m/s
C.
3 x 10^7 m/s
D.
3 x 10^9 m/s
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Solution
The speed of light in vacuum is approximately 3 x 10^8 m/s.
Correct Answer: A — 3 x 10^8 m/s
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Q. What is the temperature in Celsius if the temperature in Kelvin is 273 K?
A.
0°C
B.
100°C
C.
-273°C
D.
273°C
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Solution
To convert Kelvin to Celsius, use the formula: °C = K - 273. Therefore, 273 K - 273 = 0°C.
Correct Answer: A — 0°C
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Q. What is the temperature of a gas in Kelvin if its temperature in Celsius is 25°C? (2019)
A.
273 K
B.
298 K
C.
310 K
D.
325 K
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Solution
Temperature in Kelvin (K) = Temperature in Celsius (°C) + 273.15 = 25 + 273.15 = 298.15 K.
Correct Answer: B — 298 K
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Q. What is the thermal conductivity of a material if a 1 m² area of it conducts 100 J of heat in 10 seconds with a temperature difference of 20°C?
A.
2 W/m°C
B.
5 W/m°C
C.
10 W/m°C
D.
20 W/m°C
Show solution
Solution
Using the formula Q = kA(T1-T2)t, we find k = Q / (A(T1-T2)t) = 100 J / (1 m² * 20°C * 10 s) = 0.5 W/m°C.
Correct Answer: B — 5 W/m°C
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Q. What is the time period of a wave with a frequency of 20 Hz? (2022)
A.
0.05 s
B.
0.1 s
C.
0.2 s
D.
0.5 s
Show solution
Solution
The time period T is the reciprocal of frequency, T = 1/f. Thus, T = 1/20 Hz = 0.05 s.
Correct Answer: B — 0.1 s
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Q. What is the total current flowing through a circuit with a 9V battery and a total resistance of 3Ω? (2022)
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Solution
Using Ohm's law, I = V/R = 9V / 3Ω = 3A.
Correct Answer: B — 2A
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Q. What is the total current in a circuit with a 15V battery and two 5Ω resistors in series? (2023)
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Solution
Total resistance R = 5Ω + 5Ω = 10Ω; I = V/R = 15V / 10Ω = 1.5A.
Correct Answer: B — 2A
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