Q. In which process does the entropy of a system decrease?
A.
Isothermal expansion
B.
Adiabatic compression
C.
Isobaric heating
D.
Isothermal compression
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Solution
In adiabatic compression, the entropy of the system decreases as work is done on the gas, increasing its temperature without heat exchange.
Correct Answer:
B
— Adiabatic compression
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Q. In which situation does light undergo total internal reflection?
A.
When it passes from air to water
B.
When it passes from water to air at an angle greater than the critical angle
C.
When it passes from glass to air at any angle
D.
When it passes from air to glass
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Solution
Total internal reflection occurs when light travels from a denser medium to a less dense medium at an angle greater than the critical angle.
Correct Answer:
B
— When it passes from water to air at an angle greater than the critical angle
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Q. In which situation does total internal reflection occur?
A.
When light travels from a denser to a rarer medium
B.
When light travels from a rarer to a denser medium
C.
When light is absorbed
D.
When light is reflected
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Solution
Total internal reflection occurs when light travels from a denser medium to a rarer medium at an angle greater than the critical angle.
Correct Answer:
A
— When light travels from a denser to a rarer medium
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Q. In Young's double-slit experiment, what causes the formation of interference patterns?
A.
Reflection of light
B.
Refraction of light
C.
Superposition of waves
D.
Diffraction of waves
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Solution
The interference pattern is formed due to the superposition of waves from the two slits.
Correct Answer:
C
— Superposition of waves
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Q. In Young's double-slit experiment, what is the condition for constructive interference?
A.
d sin(θ) = (m + 0.5)λ
B.
d sin(θ) = mλ
C.
d sin(θ) = (m - 0.5)λ
D.
d sin(θ) = 0
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Solution
The condition for constructive interference in Young's double-slit experiment is d sin(θ) = mλ, where m is an integer.
Correct Answer:
B
— d sin(θ) = mλ
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Q. Two cars are moving towards each other, one at 50 km/h and the other at 70 km/h. What is the speed of one car relative to the other?
A.
20 km/h
B.
120 km/h
C.
50 km/h
D.
70 km/h
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Solution
The speed of one car relative to the other is the sum of their speeds since they are moving towards each other: 50 km/h + 70 km/h = 120 km/h.
Correct Answer:
B
— 120 km/h
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Q. Two charges, +4 µC and -4 µC, are placed 1 m apart. What is the net electric field at the midpoint between the charges?
A.
0 N/C
B.
8.99 N/C
C.
4.49 N/C
D.
17.98 N/C
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Solution
The electric fields due to both charges at the midpoint are equal in magnitude and opposite in direction, resulting in a net electric field of 0 N/C.
Correct Answer:
A
— 0 N/C
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Q. Two trains are moving towards each other on parallel tracks. Train A is moving at 90 km/h and Train B at 70 km/h. What is the speed of Train B relative to Train A?
A.
20 km/h
B.
70 km/h
C.
90 km/h
D.
160 km/h
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Solution
The speed of Train B relative to Train A is the sum of their speeds: 90 km/h + 70 km/h = 160 km/h.
Correct Answer:
D
— 160 km/h
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Q. Using Kirchhoff's Voltage Law, if a loop has a 12V source and two resistors of 3Ω and 4Ω, what is the voltage drop across the 3Ω resistor?
A.
4.29V
B.
5.14V
C.
3.43V
D.
6.0V
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Solution
Total resistance R = 3Ω + 4Ω = 7Ω. Total current I = V/R = 12V / 7Ω = 1.71A. Voltage drop across 3Ω = I * R = 1.71A * 3Ω = 5.14V.
Correct Answer:
B
— 5.14V
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Q. Using Kirchhoff's Voltage Law, what is the voltage drop across a 10Ω resistor if the total voltage in the loop is 20V and there is a 5Ω resistor in series?
A.
10V
B.
15V
C.
5V
D.
20V
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Solution
Using KVL, V_total = V_R1 + V_R2. V_R1 = 20V - (I * 5Ω). I = V/R = 20V / 15Ω = 1.33 A. V_R1 = 10Ω * 1.33 A = 13.33V.
Correct Answer:
A
— 10V
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Q. What does the Heisenberg Uncertainty Principle state?
A.
Energy and mass are interchangeable
B.
The position and momentum of a particle cannot both be precisely known
C.
Electrons can exist in multiple states simultaneously
D.
Light behaves both as a wave and a particle
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Solution
The Heisenberg Uncertainty Principle states that the position and momentum of a particle cannot both be precisely known at the same time.
Correct Answer:
B
— The position and momentum of a particle cannot both be precisely known
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Q. What does the photoelectric effect demonstrate?
A.
Light behaves only as a wave.
B.
Light can be absorbed by matter.
C.
Light has particle-like properties.
D.
Light cannot cause electron emission.
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Solution
The photoelectric effect demonstrates that light has particle-like properties, as it can cause the emission of electrons from a material when it is above a certain frequency.
Correct Answer:
C
— Light has particle-like properties.
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Q. What does the second law of thermodynamics state about entropy?
A.
Entropy can decrease in an isolated system
B.
Entropy remains constant in reversible processes
C.
Entropy of an isolated system always increases
D.
Entropy is a measure of energy
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Solution
The second law of thermodynamics states that the entropy of an isolated system always increases over time.
Correct Answer:
C
— Entropy of an isolated system always increases
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Q. What does the term 'mean free path' refer to in the context of gases?
A.
The average distance traveled by a molecule between collisions
B.
The average speed of gas molecules
C.
The average time between collisions
D.
The average kinetic energy of gas molecules
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Solution
The mean free path is defined as the average distance a molecule travels before colliding with another molecule.
Correct Answer:
A
— The average distance traveled by a molecule between collisions
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Q. What effect does temperature have on the speed of sound in air?
A.
Increases with temperature
B.
Decreases with temperature
C.
No effect
D.
Depends on humidity
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Solution
The speed of sound in air increases with an increase in temperature.
Correct Answer:
A
— Increases with temperature
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Q. What happens to the acceleration of an object if the mass is doubled while the force remains constant?
A.
It doubles
B.
It halves
C.
It remains the same
D.
It quadruples
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Solution
According to Newton's second law, if mass is doubled and force remains constant, acceleration will halve (a = F/m).
Correct Answer:
B
— It halves
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Q. What happens to the angular momentum of a rigid body if no external torque acts on it?
A.
It increases
B.
It decreases
C.
It remains constant
D.
It becomes zero
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Solution
According to the law of conservation of angular momentum, if no external torque acts on a rigid body, its angular momentum remains constant.
Correct Answer:
C
— It remains constant
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Q. What happens to the capacitance of a capacitor if the plate area is doubled while keeping the distance constant?
A.
It doubles
B.
It halves
C.
It quadruples
D.
It remains the same
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Solution
Capacitance is directly proportional to the plate area. Doubling the area doubles the capacitance.
Correct Answer:
A
— It doubles
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Q. What happens to the charge (Q) on a capacitor when it discharges through a resistor (R)?
A.
Q decreases exponentially
B.
Q remains constant
C.
Q increases linearly
D.
Q decreases linearly
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Solution
The charge on a discharging capacitor decreases exponentially over time.
Correct Answer:
A
— Q decreases exponentially
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Q. What happens to the current in a diode when the voltage is reversed beyond the breakdown voltage?
A.
It increases exponentially
B.
It decreases to zero
C.
It remains constant
D.
It becomes negative
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Solution
When the reverse voltage exceeds the breakdown voltage, the current in the diode increases exponentially, which can lead to damage if not controlled.
Correct Answer:
A
— It increases exponentially
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Q. What happens to the current in an RC circuit as time approaches infinity after the switch is closed?
A.
Current increases indefinitely
B.
Current decreases to zero
C.
Current remains constant
D.
Current oscillates
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Solution
As time approaches infinity after the switch is closed, the current in an RC circuit decreases to zero.
Correct Answer:
B
— Current decreases to zero
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Q. What happens to the electric potential energy when a positive charge moves away from another positive charge?
A.
It increases
B.
It decreases
C.
It remains the same
D.
It becomes zero
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Solution
As a positive charge moves away from another positive charge, the electric potential energy decreases due to the repulsive force.
Correct Answer:
B
— It decreases
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Q. What happens to the entropy of a system when heat is added at a constant temperature?
A.
It decreases
B.
It remains the same
C.
It increases
D.
It becomes zero
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Solution
When heat is added to a system at constant temperature, the entropy of the system increases, as entropy is a measure of disorder.
Correct Answer:
C
— It increases
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Q. What happens to the frequency of light when it passes from one medium to another?
A.
It increases
B.
It decreases
C.
It remains the same
D.
It becomes zero
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Solution
The frequency of light remains constant when it passes from one medium to another; only the speed and wavelength change.
Correct Answer:
C
— It remains the same
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Q. What happens to the gravitational force if one of the masses is tripled?
A.
It triples
B.
It remains the same
C.
It doubles
D.
It increases by a factor of nine
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Solution
If one of the masses is tripled, the gravitational force also triples, as F is directly proportional to the product of the masses.
Correct Answer:
A
— It triples
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Q. What happens to the induced current if the magnetic field is removed?
A.
It increases
B.
It decreases
C.
It reverses direction
D.
It stops
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Solution
If the magnetic field is removed, the induced current stops because there is no longer a change in magnetic flux.
Correct Answer:
D
— It stops
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Q. What happens to the photoelectric effect if the frequency of light is below the threshold frequency?
A.
Electrons are emitted with high energy
B.
No electrons are emitted
C.
Electrons are emitted with low energy
D.
Electrons are emitted but are not detected
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Solution
If the frequency of light is below the threshold frequency, no electrons are emitted from the metal surface.
Correct Answer:
B
— No electrons are emitted
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Q. What happens to the resistance of a diode when it is forward-biased?
A.
It increases significantly
B.
It remains constant
C.
It decreases significantly
D.
It becomes infinite
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Solution
When a diode is forward-biased, its resistance decreases significantly, allowing current to flow easily.
Correct Answer:
C
— It decreases significantly
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Q. What happens to the speed of light when it passes from air into water?
A.
It increases
B.
It decreases
C.
It remains the same
D.
It becomes zero
Show solution
Solution
The speed of light decreases when it passes from air into water due to the higher refractive index of water.
Correct Answer:
B
— It decreases
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Q. What happens to the total capacitance when capacitors are connected in series?
A.
It increases
B.
It decreases
C.
It remains the same
D.
It becomes zero
Show solution
Solution
When capacitors are connected in series, the total capacitance decreases and is given by the formula 1/C_total = 1/C1 + 1/C2 + ... + 1/Cn.
Correct Answer:
B
— It decreases
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