Physics Syllabus (JEE Main)
Q. What is the principle behind sonar technology?
A.
Reflection of sound waves
B.
Refraction of sound waves
C.
Diffraction of sound waves
D.
Interference of sound waves
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Solution
Sonar technology is based on the reflection of sound waves to detect objects underwater.
Correct Answer: A — Reflection of sound waves
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Q. What is the principle behind the Doppler effect?
A.
Change in frequency due to relative motion
B.
Change in amplitude due to distance
C.
Change in speed due to medium
D.
Change in wavelength due to temperature
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Solution
The Doppler effect is the change in frequency (and wavelength) of a wave in relation to an observer moving relative to the wave source.
Correct Answer: A — Change in frequency due to relative motion
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Q. What is the principle behind the operation of a laser?
A.
Spontaneous emission
B.
Stimulated emission
C.
Absorption
D.
Reflection
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Solution
Lasers operate on the principle of stimulated emission, where an incoming photon stimulates an excited electron to emit a photon of the same energy, phase, and direction.
Correct Answer: B — Stimulated emission
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Q. What is the principle behind the operation of a polarimeter?
A.
Measuring the speed of light
B.
Determining the wavelength of light
C.
Measuring the rotation of polarized light
D.
Calculating the intensity of light
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Solution
A polarimeter measures the angle of rotation of polarized light as it passes through a sample, which can indicate the concentration of optically active substances.
Correct Answer: C — Measuring the rotation of polarized light
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Q. What is the principle behind the operation of a transformer?
A.
Conservation of energy
B.
Electromagnetic induction
C.
Thermal expansion
D.
Mechanical advantage
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Solution
Transformers operate on the principle of electromagnetic induction, where a changing magnetic field induces an electromotive force (EMF) in a coil.
Correct Answer: B — Electromagnetic induction
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Q. What is the principle behind the operation of an electric generator?
A.
Electromagnetic induction
B.
Thermal expansion
C.
Photoelectric effect
D.
Chemical reaction
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Solution
Electric generators operate on the principle of electromagnetic induction, converting mechanical energy into electrical energy.
Correct Answer: A — Electromagnetic induction
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Q. What is the principle behind the operation of an electric motor?
A.
Electromagnetic induction
B.
Lorentz force
C.
Magnetic resonance
D.
Thermal expansion
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Solution
Electric motors operate on the principle of the Lorentz force, where a current-carrying conductor in a magnetic field experiences a force that causes it to rotate.
Correct Answer: B — Lorentz force
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Q. What is the principle behind the working of a 3D movie glasses?
A.
Color filtering
B.
Polarization
C.
Refraction
D.
Diffraction
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Solution
3D movie glasses use polarization to filter different images for each eye, creating a three-dimensional effect.
Correct Answer: B — Polarization
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Q. What is the principle behind the working of a hydraulic lift?
A.
Bernoulli's principle
B.
Archimedes' principle
C.
Pascal's law
D.
Newton's law
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Solution
A hydraulic lift works on Pascal's law, which states that pressure applied to a confined fluid is transmitted undiminished in all directions.
Correct Answer: C — Pascal's law
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Q. What is the principle behind the working of a sonar?
A.
Reflection of sound waves
B.
Refraction of sound waves
C.
Diffraction of sound waves
D.
Interference of sound waves
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Solution
Sonar works on the principle of reflection of sound waves to detect objects underwater.
Correct Answer: A — Reflection of sound waves
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Q. What is the principle behind the working of a transformer?
A.
Conservation of energy
B.
Electromagnetic induction
C.
Thermal expansion
D.
Mechanical advantage
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Solution
Transformers work on the principle of electromagnetic induction, where a changing magnetic field induces an electromotive force (EMF) in a coil.
Correct Answer: B — Electromagnetic induction
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Q. What is the principle behind the working of an electric generator?
A.
Electromagnetic induction
B.
Electrolysis
C.
Thermal expansion
D.
Photoelectric effect
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Solution
An electric generator works on the principle of electromagnetic induction, where mechanical energy is converted into electrical energy by moving a conductor through a magnetic field.
Correct Answer: A — Electromagnetic induction
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Q. What is the principle behind the working of an electric motor?
A.
Electromagnetic induction
B.
Lorentz force
C.
Magnetic resonance
D.
Electrolysis
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Solution
An electric motor operates on the principle of the Lorentz force, which states that a current-carrying conductor in a magnetic field experiences a force.
Correct Answer: B — Lorentz force
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Q. What is the principle of a potentiometer?
A.
It measures current in a circuit.
B.
It measures voltage by balancing it against a known voltage.
C.
It measures resistance directly.
D.
It measures power in a circuit.
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Solution
A potentiometer measures voltage by balancing it against a known voltage, allowing for accurate voltage measurements.
Correct Answer: B — It measures voltage by balancing it against a known voltage.
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Q. What is the principle of conservation of momentum?
A.
Energy cannot be created or destroyed
B.
The total momentum of a closed system remains constant
C.
Force equals mass times acceleration
D.
Work done is equal to energy transferred
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Solution
The principle of conservation of momentum states that the total momentum of a closed system remains constant if no external forces act on it.
Correct Answer: B — The total momentum of a closed system remains constant
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Q. What is the principle of superposition in optics?
A.
Light travels in straight lines
B.
Two waves can interfere to form a resultant wave
C.
Light can be polarized
D.
Light can be diffracted
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Solution
The principle of superposition states that when two or more waves overlap, the resultant displacement is the sum of the individual displacements.
Correct Answer: B — Two waves can interfere to form a resultant wave
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Q. What is the principle of superposition in wave motion?
A.
Waves can only travel in one direction
B.
Waves can interfere with each other
C.
Waves cannot pass through each other
D.
Waves always lose energy
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Solution
The principle of superposition states that when two or more waves overlap, the resultant displacement is the sum of the individual displacements.
Correct Answer: B — Waves can interfere with each other
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Q. What is the principle of superposition in wave theory?
A.
Waves can only interfere constructively
B.
Waves can only interfere destructively
C.
The resultant wave is the sum of individual waves
D.
Waves do not interact with each other
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Solution
The principle of superposition states that when two or more waves overlap, the resultant wave is the sum of the individual waves.
Correct Answer: C — The resultant wave is the sum of individual waves
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Q. What is the process called when a heavy nucleus splits into two lighter nuclei?
A.
Nuclear fusion
B.
Nuclear fission
C.
Radioactive decay
D.
Nuclear transmutation
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Solution
Nuclear fission is the process in which a heavy nucleus splits into two lighter nuclei, releasing energy in the process.
Correct Answer: B — Nuclear fission
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Q. What is the product of 3.00 and 2.5, considering significant figures?
A.
7.5
B.
7.50
C.
7.500
D.
7.55
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Solution
In multiplication, the result should have the same number of significant figures as the factor with the least significant figures. 3.00 has 3 significant figures and 2.5 has 2 significant figures, so the result should have 2 significant figures: 7.5.
Correct Answer: A — 7.5
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Q. What is the purpose of a demodulator in a communication system?
A.
To encode the signal for transmission
B.
To convert the modulated signal back to its original form
C.
To amplify the received signal
D.
To filter out unwanted frequencies
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Solution
A demodulator's purpose is to convert the modulated signal back to its original baseband form for further processing.
Correct Answer: B — To convert the modulated signal back to its original form
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Q. What is the purpose of a galvanometer in a Wheatstone bridge?
A.
To measure voltage
B.
To measure current
C.
To detect the balance condition
D.
To provide power
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Solution
A galvanometer is used to detect the balance condition in a Wheatstone bridge by indicating zero current when balanced.
Correct Answer: C — To detect the balance condition
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Q. What is the purpose of the galvanometer in a Wheatstone bridge?
A.
To measure voltage
B.
To measure current
C.
To detect the balance condition
D.
To provide power
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Solution
The galvanometer is used to detect the balance condition by indicating the current flow.
Correct Answer: C — To detect the balance condition
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Q. What is the range of human hearing in Hertz?
A.
20 Hz to 20 kHz
B.
20 kHz to 20 MHz
C.
1 Hz to 100 kHz
D.
10 Hz to 10 kHz
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Solution
The typical range of human hearing is from 20 Hz to 20 kHz.
Correct Answer: A — 20 Hz to 20 kHz
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Q. What is the range of human hearing in terms of frequency?
A.
20 Hz to 20 kHz
B.
20 kHz to 20 MHz
C.
1 Hz to 100 kHz
D.
100 Hz to 10 kHz
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Solution
The typical range of human hearing is from 20 Hz to 20 kHz.
Correct Answer: A — 20 Hz to 20 kHz
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Q. What is the refractive index of a medium if the critical angle for total internal reflection is 30° when light travels to air?
A.
1.73
B.
1.00
C.
1.41
D.
1.50
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Solution
Using sin(30°) = 0.5, n = 1/sin(30°) = 1/0.5 = 2. Therefore, the refractive index is 2.
Correct Answer: A — 1.73
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Q. What is the refractive index of a medium if the critical angle for total internal reflection is 30°?
A.
1.00
B.
1.15
C.
1.73
D.
2.00
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Solution
Using the formula n = 1/sin(θc), where θc = 30°, we find n = 1/sin(30°) = 1/0.5 = 2.00.
Correct Answer: C — 1.73
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Q. What is the relationship between angular momentum L and moment of inertia I for a rotating object?
A.
L = Iω
B.
L = I²ω
C.
L = ω/I
D.
L = I + ω
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Solution
Angular momentum L is given by L = Iω, where ω is the angular velocity.
Correct Answer: A — L = Iω
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Q. What is the relationship between bulk modulus and compressibility?
A.
Bulk modulus is the inverse of compressibility
B.
Bulk modulus is equal to compressibility
C.
Bulk modulus is the square of compressibility
D.
There is no relationship
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Solution
Bulk modulus is defined as the reciprocal of compressibility, indicating how incompressible a material is.
Correct Answer: A — Bulk modulus is the inverse of compressibility
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Q. What is the relationship between Celsius and Kelvin?
A.
K = C + 273.15
B.
K = C - 273.15
C.
C = K + 273.15
D.
C = K - 273.15
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Solution
The relationship is K = C + 273.15, where K is the temperature in Kelvin and C is the temperature in Celsius.
Correct Answer: A — K = C + 273.15
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