Q. What is the change in entropy when 1 kg of water at 100°C is converted to steam at 100°C?
A.
2260 J/K
B.
100 J/K
C.
540 J/K
D.
0 J/K
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Solution
The change in entropy (ΔS) for the phase change is calculated as ΔS = Q/T = 2260 J / 373 K = 6.06 J/K, but for 1 kg, it is 2260 J/K.
Correct Answer:
A
— 2260 J/K
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Q. What is the change in entropy when 1 mole of an ideal gas expands isothermally from 10 L to 20 L at 300 K?
A.
0.5 J/K
B.
1.0 J/K
C.
1.5 J/K
D.
2.0 J/K
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Solution
ΔS = nR ln(Vf/Vi) = 1 * 8.314 * ln(20/10) = 1.0 J/K.
Correct Answer:
B
— 1.0 J/K
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Q. What is the charge stored in a capacitor of 5 µF at a voltage of 10 V?
A.
50 µC
B.
100 µC
C.
25 µC
D.
75 µC
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Solution
Charge Q = C * V = 5 x 10^-6 F * 10 V = 50 µC.
Correct Answer:
A
— 50 µC
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Q. What is the charge stored in a capacitor of 5 µF when connected to a 10 V battery?
A.
0.05 mC
B.
0.1 mC
C.
0.2 mC
D.
0.5 mC
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Solution
Charge Q = C * V = 5 x 10^-6 F * 10 V = 0.05 mC.
Correct Answer:
B
— 0.1 mC
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Q. What is the coefficient of linear expansion for a material that expands 0.01 m when heated from 20°C to 100°C over a length of 2 m?
A.
5 x 10^-5 /°C
B.
1 x 10^-4 /°C
C.
2 x 10^-4 /°C
D.
1 x 10^-5 /°C
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Solution
The coefficient of linear expansion α = ΔL / (L0 * ΔT) = 0.01 / (2 * 80) = 1.25 x 10^-5 /°C.
Correct Answer:
B
— 1 x 10^-4 /°C
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Q. What is the coefficient of linear expansion for a material that expands by 0.01 m when heated from 20°C to 100°C over a length of 2 m?
A.
5 x 10^-5 /°C
B.
1 x 10^-4 /°C
C.
2 x 10^-4 /°C
D.
1.5 x 10^-4 /°C
Show solution
Solution
The coefficient of linear expansion (α) is calculated as α = ΔL / (L0 * ΔT) = 0.01 / (2 * 80) = 1 x 10^-4 /°C.
Correct Answer:
B
— 1 x 10^-4 /°C
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Q. What is the concept of time dilation in special relativity?
A.
Time moves faster for objects in motion.
B.
Time moves slower for objects in motion.
C.
Time is the same for all observers.
D.
Time can be reversed.
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Solution
Time dilation is a phenomenon in special relativity where time is observed to move slower for an object in motion relative to a stationary observer.
Correct Answer:
B
— Time moves slower for objects in motion.
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Q. What is the concept of wave-particle duality?
A.
Particles can exhibit both wave-like and particle-like properties.
B.
Waves can only exist in one state at a time.
C.
Particles cannot interfere with each other.
D.
Light can only behave as a wave.
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Solution
Wave-particle duality is a fundamental concept in quantum mechanics that states that every particle or quantum entity can be described as either a particle or a wave, depending on the experimental conditions.
Correct Answer:
A
— Particles can exhibit both wave-like and particle-like properties.
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Q. What is the condition for a rolling object to be in pure rolling motion?
A.
The object must not slide at all.
B.
The object must have a constant velocity.
C.
The object must have a constant acceleration.
D.
The object must be on a flat surface.
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Solution
Pure rolling motion occurs when the point of contact between the rolling object and the surface is at rest relative to the surface, meaning there is no sliding.
Correct Answer:
A
— The object must not slide at all.
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Q. What is the condition for constructive interference in two coherent waves?
A.
Path difference = (n + 0.5)λ
B.
Path difference = nλ
C.
Path difference = (n + 1)λ/2
D.
Path difference = (n - 0.5)λ
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Solution
Constructive interference occurs when the path difference between two coherent waves is an integer multiple of the wavelength, nλ.
Correct Answer:
B
— Path difference = nλ
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Q. What is the condition for constructive interference of two waves?
A.
Path difference is an odd multiple of half the wavelength
B.
Path difference is an even multiple of the wavelength
C.
Waves are out of phase
D.
Waves are in phase
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Solution
Constructive interference occurs when the path difference between two waves is an even multiple of the wavelength.
Correct Answer:
B
— Path difference is an even multiple of the wavelength
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Q. What is the critical angle for total internal reflection from glass (n=1.5) to air (n=1)?
A.
41.8 degrees
B.
48.6 degrees
C.
60 degrees
D.
90 degrees
Show solution
Solution
The critical angle can be calculated using sin(θc) = n2/n1, which gives θc = sin^(-1)(1/1.5) = 41.8 degrees.
Correct Answer:
A
— 41.8 degrees
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Q. What is the critical angle for total internal reflection?
A.
sin(θc) = n2/n1
B.
sin(θc) = n1/n2
C.
θc = n1/n2
D.
θc = n2/n1
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Solution
The critical angle θc can be calculated using sin(θc) = n2/n1, where n1 is the refractive index of the medium where the light is coming from.
Correct Answer:
A
— sin(θc) = n2/n1
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Q. What is the current flowing through a 20 Ω resistor when a voltage of 100 V is applied?
A.
5 A
B.
10 A
C.
15 A
D.
20 A
Show solution
Solution
Using Ohm's Law: I = V / R = 100 V / 20 Ω = 5 A.
Correct Answer:
B
— 10 A
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Q. What is the current through a 10 Ω resistor if the voltage across it is 30 V?
A.
3 A
B.
1 A
C.
5 A
D.
2 A
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Solution
Using Ohm's Law: I = V/R = 30 V / 10 Ω = 3 A.
Correct Answer:
A
— 3 A
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Q. What is the current through a 12Ω resistor connected to a 36V source?
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Solution
Using Ohm's law, I = V/R = 36V / 12Ω = 3A.
Correct Answer:
B
— 3A
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Q. What is the current through a 15 ohm resistor connected to a 45V source?
A.
3 A
B.
2 A
C.
1 A
D.
4 A
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Solution
Using Ohm's Law, I = V/R. Here, I = 45V / 15Ω = 3 A.
Correct Answer:
A
— 3 A
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Q. What is the current through a 5 Ω resistor connected to a 15 V battery?
A.
3 A
B.
2 A
C.
1 A
D.
0.5 A
Show solution
Solution
Using Ohm's law, I = V/R = 15 V / 5 Ω = 3 A.
Correct Answer:
B
— 2 A
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Q. What is the current through a 5Ω resistor if the voltage across it is 15V?
A.
3 A
B.
2 A
C.
1 A
D.
4 A
Show solution
Solution
Using Ohm's law, I = V/R = 15V / 5Ω = 3 A.
Correct Answer:
A
— 3 A
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Q. What is the dielectric constant of a material if a capacitor with air as dielectric has a capacitance of 10 µF and the same capacitor with the material has a capacitance of 30 µF?
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Solution
Dielectric constant ε_r = C_material / C_air = 30 µF / 10 µF = 3.
Correct Answer:
C
— 3
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Q. What is the effect of a prism on white light?
A.
Reflection
B.
Refraction
C.
Dispersion
D.
Absorption
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Solution
A prism disperses white light into its constituent colors due to refraction.
Correct Answer:
C
— Dispersion
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Q. What is the effect of adding a dielectric to a capacitor?
A.
Increases capacitance
B.
Decreases capacitance
C.
No effect on capacitance
D.
Increases resistance
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Solution
Adding a dielectric increases the capacitance of the capacitor.
Correct Answer:
A
— Increases capacitance
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Q. What is the effect of connecting a capacitor in parallel with a resistor in a DC circuit?
A.
Increases current
B.
Decreases current
C.
Stores energy
D.
No effect
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Solution
A capacitor stores energy when connected in parallel with a resistor, affecting the circuit's behavior over time.
Correct Answer:
C
— Stores energy
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Q. What is the effect of friction on the motion of an object according to Newton's laws?
A.
It increases acceleration
B.
It decreases acceleration
C.
It has no effect
D.
It reverses direction
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Solution
Friction opposes the motion of an object, thus decreasing its acceleration according to Newton's laws.
Correct Answer:
B
— It decreases acceleration
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Q. What is the effect of increasing the area of a loop in a uniform magnetic field on the induced emf?
A.
Induced emf increases
B.
Induced emf decreases
C.
Induced emf remains the same
D.
Induced emf becomes zero
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Solution
The induced emf depends on the rate of change of magnetic flux, not directly on the area of the loop in a uniform magnetic field. Therefore, it remains the same if the magnetic field is constant.
Correct Answer:
C
— Induced emf remains the same
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Q. What is the effect of increasing the capacitance in an RC circuit on the time constant?
A.
Time constant decreases
B.
Time constant increases
C.
Time constant remains the same
D.
Time constant becomes zero
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Solution
Increasing the capacitance in an RC circuit increases the time constant τ = R*C, making the charging and discharging processes slower.
Correct Answer:
B
— Time constant increases
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Q. What is the effect of increasing the distance between the plates of a parallel plate capacitor?
A.
Capacitance increases
B.
Capacitance decreases
C.
Capacitance remains the same
D.
Capacitance becomes zero
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Solution
Capacitance decreases as the distance between the plates increases.
Correct Answer:
B
— Capacitance decreases
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Q. What is the effect of increasing the distance between the plates of a parallel plate capacitor on its capacitance?
A.
Capacitance increases
B.
Capacitance decreases
C.
Capacitance remains the same
D.
Capacitance becomes zero
Show solution
Solution
Capacitance (C) is inversely proportional to the distance (d) between the plates. Increasing d decreases C.
Correct Answer:
B
— Capacitance decreases
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Q. What is the effect of increasing the distance between two masses on the gravitational force?
A.
The gravitational force increases.
B.
The gravitational force decreases.
C.
The gravitational force remains the same.
D.
The gravitational force becomes zero.
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Solution
According to the inverse square law, increasing the distance between two masses decreases the gravitational force between them.
Correct Answer:
B
— The gravitational force decreases.
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Q. What is the effect of increasing the intensity of light on the photoelectric effect?
A.
It increases the energy of emitted electrons
B.
It increases the number of emitted electrons
C.
It decreases the threshold frequency
D.
It has no effect on the photoelectric effect
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Solution
Increasing the intensity of light increases the number of photons hitting the surface, which in turn increases the number of emitted electrons, provided the frequency is above the threshold.
Correct Answer:
B
— It increases the number of emitted electrons
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