CUET UG Physics Booster Test 3-Mathematical Principles and Laws
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QUESTION 1 OF 20
The missing term in Ampere's circuital law was found by analyzing the electric flux through surface S.
QUESTION 2 OF 20
If the charge Q on capacitor plates changes with time, a displacement current arises.
1. It relies on i = dQ/dt
2. It equals ε₀(dΦE/dt)
3. It maintains the continuity of total current across the capacitor
4. It nullifies the existence of Ex
QUESTION 3 OF 20
If the magnetic field in a plane EM wave is
By = (2 × 10⁻⁷) sin(0.5 × 10³x + 1.5 × 10¹¹t) T,
what is its wavelength?
QUESTION 4 OF 20
Field source states are:
QUESTION 5 OF 20
Match List I with List II
| List I | List II |
|---|---|
| 1. Time-varying B field | a. Induces E field |
| 2. Time-varying E field | b. Induces B field |
| 3. Accelerated charge | c. Radiates EM waves |
| 4. Static charge | d. Produces electrostatic field only |
QUESTION 6 OF 20
Faraday's law of electromagnetic induction states:
Statements
1. The induced emf is strictly zero if the magnetic flux is constant
2. The line integral ∮E·dl computes the induced emf
3. It provides the symmetrical counterpart to displacement current
4. It restricts electric fields to static charge origins only
QUESTION 7 OF 20
Identify the incorrect statement regarding sinusoidal wave equations:
QUESTION 8 OF 20
Choose the correct statements about ω and k:
1. ω = ck relates the temporal and spatial frequencies
2. k = 2π/λ connects wave number to wavelength
3. ω is defined as 2π/ν
4. The speed of the wave equals ω/k
QUESTION 9 OF 20
If an electromagnetic wave's frequency ν is 2.0 × 10¹⁰ Hz, its wavelength λ in vacuum is:
(c = 3 × 10⁸ m/s)
QUESTION 10 OF 20
As electromagnetic waves propagate through glass rather than a vacuum, the changes observed are dictated by the medium's properties. Choose the correct statements:
1. The total fields differ from the external fields by factors ε and μ
2. The velocity reduces due to the material's permittivity and permeability
3. The speed equation becomes v = 1/√(μ₀ε₀)
4. Glass acts as a perfect insulator blocking all fields
QUESTION 11 OF 20
Match List I with List II
| List I | List II |
|---|---|
| 1. E₀ | a. Amplitude of electric field |
| 2. B₀ | b. Amplitude of magnetic field |
| 3. c | c. E₀/B₀ |
| 4. Propagation direction | d. E × B |
QUESTION 12 OF 20
If the amplitude of the electric field E₀ = 48 V/m, what is the maximum magnetic field amplitude B₀?
(c = 3 × 10⁸ m/s)
QUESTION 13 OF 20
Identify the incorrect statement regarding the energy associated with an electromagnetic wave:
QUESTION 14 OF 20
Choose the correct statements about electromagnetic wave energy transfer:
1. Light carries energy from the sun to the earth.
2. Radio and TV signals carry energy via self-sustaining oscillations.
3. The magnetic field energy density completely outscales the electric field energy density.
4. The average energy densities of both fields are equal.
QUESTION 15 OF 20
If the electric field is in the +y direction and the wave travels in the +x direction, the magnetic field is strictly defined.
1. The cross product requires B to be in the +z direction
2. The cross product ĵ × k̂ = î satisfies the condition
3. The magnetic field aligns with the x-axis
4. The electric field aligns with the z-axis
QUESTION 16 OF 20
To ensure the logical consistency of Maxwell's equations, it was found that the fields inside a parallel plate capacitor demonstrate orthogonality.
1. The electric field is perpendicular to the plates.
2. The magnetic field circles parallel to the plates.
3. B and E are entirely parallel.
4. The displacement current induces a parallel electric field.
QUESTION 17 OF 20
If a wave possesses a frequency of 10⁹ Hz, what is the wavelength of the electromagnetic wave produced?
(c = 3 × 10⁸ m/s)
QUESTION 18 OF 20
Because of the strong experimental backing of the constant velocity of EM waves in vacuum, the scientific community
QUESTION 19 OF 20
Photon scales:
QUESTION 20 OF 20
Match List I with List II
| List I | List II |
|---|---|
| 1. Ultraviolet rays | a. 400 nm to 1 nm |
| 2. Infrared waves | b. 1 mm to 700 nm |
| 3. Gamma rays | c. < 10⁻³ nm |
| 4. Microwaves | d. 0.1 m to 1 mm |
Test Complete!
Answer Review
1 The missing term in Ampere's circuital law was found by analyzing the electric flux through surface S.
�� Maxwell analyzed charging capacitors. �� Electric flux was related to enclosed charge. �� This led to displacement current.
Maxwell used Gauss's law: ΦE = Q/ε₀ Differentiating with respect to time gives: dΦE/dt = (1/ε₀)dQ/dt Since dQ/dt = i, Maxwell obtained: Id = ε₀(dΦE/dt) This introduced displacement current into Ampere's law. Therefore Option A is correct.
- �� Option B → Faraday's law deals with magnetic flux, not electric flux.
- �� Option C → Magnetic field integral does not replace charge.
- �� Option D → Surface charge integration alone does not directly give conduction current.
Used
- Concept Recall
Application:
- Recall Maxwell's derivation of displacement current.
Final Logic:
- Gauss's law provided the electric-flux relation needed for Maxwell's correction.
Gauss → Flux → Displacement Current
2 If the charge Q on capacitor plates changes with time, a displacement current arises.
1. It relies on i = dQ/dt
2. It equals ε₀(dΦE/dt)
3. It maintains the continuity of total current across the capacitor
4. It nullifies the existence of Ex
�� Changing charge creates changing electric flux. �� Displacement current complements conduction current. �� Current continuity is preserved.
Statement 1 is correct because current is: i = dQ/dt Statement 2 is correct: Id = ε₀(dΦE/dt) Statement 3 is correct because displacement current ensures continuity across the capacitor gap. Statement 4 is incorrect because displacement current does not eliminate electric fields. Hence Statements 1, 2 and 3 are correct.
- �� Option B → Includes incorrect Statement 4.
- �� Option C → Includes incorrect Statement 4.
- �� Option D → Includes incorrect Statement 4.
Used
- Elimination
Application:
- Reject the statement contradicting Maxwell's theory.
Final Logic:
- Displacement current supports electric fields rather than removing them.
Changing Flux = Displacement Current
3 If the magnetic field in a plane EM wave is
By = (2 × 10⁻⁷) sin(0.5 × 10³x + 1.5 × 10¹¹t) T,
what is its wavelength?
�� Wave number k = 0.5 × 10³ rad/m. �� λ = 2π/k. �� Convert to centimeters.
Given: k = 0.5 × 10³ = 500 rad/m Using: λ = 2π/k = 6.283/500 = 0.01257 m = 1.26 cm Therefore Option A is correct.
- �� Option B → Calculation error.
- �� Option C → Incorrect substitution.
- �� Option D → Much larger than actual value.
Used
- Substitution
Application:
- Use λ = 2π/k directly.
Final Logic:
- λ = 1.26 cm.
λ = 2π/k
4 Field source states are:
�� Electric charges exist. �� Magnetic monopoles have not been observed. �� Maxwell's equations reflect this asymmetry.
Electric fields originate from electric charges, which exist. Magnetic monopoles have never been experimentally detected. Thus source states are: Electric charge → Existent Magnetic monopole → Non-existent Hence Option B is correct.
- �� Option A → Does not describe source existence.
- �� Option C → Not relevant to field sources.
- �� Option D → Describes geometry, not sources.
Used
- Concept Recall
Application:
- Recall Gauss's laws for electricity and magnetism.
Final Logic:
- Charges exist; monopoles do not.
Charge Exists, Monopole Missing
5 Match List I with List II
| List I | List II |
|---|---|
| 1. Time-varying B field | a. Induces E field |
| 2. Time-varying E field | b. Induces B field |
| 3. Accelerated charge | c. Radiates EM waves |
| 4. Static charge | d. Produces electrostatic field only |
�� Changing magnetic fields induce electric fields. �� Changing electric fields induce magnetic fields. �� Accelerated charges radiate.
A time-varying magnetic field induces an electric field according to Faraday's Law of Electromagnetic Induction. A time-varying electric field produces a magnetic field through the displacement current term in Maxwell's equations. An accelerated charge emits electromagnetic radiation and is therefore a source of EM waves. A static charge produces only an electrostatic field and does not radiate electromagnetic waves. Therefore: 1 → a 2 → b 3 → c 4 → d Hence, Option A is correct.
- �� Option B → First two relations are reversed.
- �� Option C → Multiple incorrect pairings.
- �� Option D → Accelerated charge incorrectly matched.
Used
- Option Grouping
Application:
- Associate each phenomenon with Maxwell's theory.
Final Logic:
- Changing fields generate each other; accelerated charges radiate.
Changing B→E, Changing E→B
6 Faraday's law of electromagnetic induction states:
Statements
1. The induced emf is strictly zero if the magnetic flux is constant
2. The line integral ∮E·dl computes the induced emf
3. It provides the symmetrical counterpart to displacement current
4. It restricts electric fields to static charge origins only
�� Faraday's law links changing flux and emf. �� Induced emf equals line integral of E. �� It is complementary to Maxwell's displacement current concept.
Statements 1, 2 and 3 are correct. If magnetic flux remains constant: emf = −dΦB/dt = 0 Also: ∮E·dl = −dΦB/dt Statement 4 is incorrect because electric fields can arise from changing magnetic fields.
- �� Option B → Includes incorrect Statement 4.
- �� Option C → Includes incorrect Statement 4.
- �� Option D → Includes incorrect Statement 4.
Used
- Elimination
Application:
- Remove the statement contradicting Faraday's law.
Final Logic:
- Electric fields need not originate only from charges.
Changing B Creates E
7 Identify the incorrect statement regarding sinusoidal wave equations:
�� k governs spatial variation. �� ω governs temporal variation. �� E and B remain in phase.
The period of oscillation in time depends on ω. k determines wavelength and spatial variation. Therefore Option B is incorrect.
- �� Option A → Correct phase expression.
- �� Option C → E and B are in phase.
- �� Option D → Substitution gives instantaneous field values.
Used
- Concept Recall
Application:
- Separate spatial and temporal parameters.
Final Logic:
- k controls space, ω controls time.
k→Space, ω→Time
8 Choose the correct statements about ω and k:
1. ω = ck relates the temporal and spatial frequencies
2. k = 2π/λ connects wave number to wavelength
3. ω is defined as 2π/ν
4. The speed of the wave equals ω/k
�� ω = ck. �� k = 2π/λ. �� v = ω/k.
Statements 1, 2 and 4 are correct. Statement 3 is incorrect. Correct relation: ω = 2πν not 2π/ν. Therefore Option A is correct.
- �� Option B → Includes incorrect Statement 3.
- �� Option C → Includes incorrect Statement 3.
- �� Option D → Includes incorrect Statement 3.
Used
- Formula Recall
Application:
- Use standard wave equations.
Final Logic:
- ω = 2πν and v = ω/k.
ω = 2πν
9 If an electromagnetic wave's frequency ν is 2.0 × 10¹⁰ Hz, its wavelength λ in vacuum is:
(c = 3 × 10⁸ m/s)
�� λ = c/ν. �� Substitute given values. �� Convert carefully.
λ = c/ν = (3 × 10⁸)/(2 × 10¹⁰) = 1.5 × 10⁻² m Hence Option A is correct.
- �� Option B → Wrong power of ten.
- �� Option C → Physically impossible.
- �� Option D → Calculation error.
Used
- Substitution
Application:
- Use λ = c/ν.
Final Logic:
- λ = 1.5 × 10⁻² m.
λ = c/ν
10 As electromagnetic waves propagate through glass rather than a vacuum, the changes observed are dictated by the medium's properties. Choose the correct statements:
1. The total fields differ from the external fields by factors ε and μ
2. The velocity reduces due to the material's permittivity and permeability
3. The speed equation becomes v = 1/√(μ₀ε₀)
4. Glass acts as a perfect insulator blocking all fields
�� Material properties influence EM waves. �� Wave speed decreases in glass. �� ε and μ determine behavior.
Statement 1 is correct because fields inside materials are affected by the medium's electric and magnetic properties. Statement 2 is correct because: v = 1/√(με) and typically v < c. Statement 3 is incorrect because 1/√(μ₀ε₀) applies only to vacuum. Statement 4 is incorrect because glass transmits light and does not block all fields. Therefore Statements 1 and 2 are correct.
- �� Option B → Both statements are incorrect.
- �� Option C → Includes incorrect Statement 3.
- �� Option D → Includes incorrect Statement 4.
Used
- Elimination
Application:
- Identify statements applicable specifically to material media.
Final Logic:
- Medium properties reduce wave speed and modify field behavior.
Glass: v < c
11 Match List I with List II
| List I | List II |
|---|---|
| 1. E₀ | a. Amplitude of electric field |
| 2. B₀ | b. Amplitude of magnetic field |
| 3. c | c. E₀/B₀ |
| 4. Propagation direction | d. E × B |
�� E₀ denotes electric field amplitude. �� B₀ denotes magnetic field amplitude. �� E × B gives propagation direction.
E₀ represents the maximum (amplitude) value of the electric field. B₀ represents the maximum (amplitude) value of the magnetic field. For an electromagnetic wave, the speed of light is given by: c = E₀/B₀ The direction of propagation of an electromagnetic wave is given by the vector product E × B (the direction of the Poynting vector). Therefore: 1 → a 2 → b 3 → c 4 → d Hence, Option A is correct.
- �� Option B → Electric and magnetic amplitudes are interchanged.
- �� Option C → Physical quantities are mismatched.
- �� Option D → Multiple incorrect pairings.
Used
- Option Grouping
Application:
- Match each physical quantity with its definition.
Final Logic:
- Standard EM-wave relations uniquely determine the matching.
E, B, c, E×B
12 If the amplitude of the electric field E₀ = 48 V/m, what is the maximum magnetic field amplitude B₀?
(c = 3 × 10⁸ m/s)
�� E₀ = cB₀. �� B₀ = E₀/c. �� Substitute the values.
Using: B₀ = E₀/c = 48/(3 × 10⁸) = 16 × 10⁻⁸ = 1.6 × 10⁻⁷ T Therefore Option A is correct.
- �� Option B → Obtained by multiplying instead of dividing.
- �� Option C → Ignores EM-wave relation.
- �� Option D → Incorrect decimal placement.
Used
- Substitution
Application:
- Apply B₀ = E₀/c directly.
Final Logic:
- 48 ÷ (3 × 10⁸) = 1.6 × 10⁻⁷ T.
B = E/c
13 Identify the incorrect statement regarding the energy associated with an electromagnetic wave:
�� EM waves are self-sustaining. �� Accelerated charges generate waves. �� Stationary charges do not sustain propagation.
Electromagnetic waves propagate due to mutually regenerating electric and magnetic fields. Their propagation does not rely on stationary charges. Energy is transported through space by the electromagnetic fields themselves. Therefore Option B is incorrect.
- �� Option A → Correct; average electric and magnetic energy densities are equal.
- �� Option C → Correct; accelerated charges are the source of radiation.
- �� Option D → Correct; EM waves transport energy without transporting matter.
Used
- Odd One Out
Application:
- Identify the statement contradicting EM-wave propagation.
Final Logic:
- Propagation is maintained by oscillating fields, not stationary charges.
Accelerated Charge → Radiation
14 Choose the correct statements about electromagnetic wave energy transfer:
1. Light carries energy from the sun to the earth.
2. Radio and TV signals carry energy via self-sustaining oscillations.
3. The magnetic field energy density completely outscales the electric field energy density.
4. The average energy densities of both fields are equal.
�� EM waves transport energy. �� Electric and magnetic energy densities are equal on average. �� Radio signals are energy-carrying EM waves.
Statements 1 and 2 are correct because EM waves transport energy over large distances. Statement 4 is correct because: Average Electric Energy Density = Average Magnetic Energy Density Statement 3 is incorrect because neither field dominates the average energy density. Hence Statements 1, 2 and 4 are correct.
- �� Option B → Includes incorrect Statement 3.
- �� Option C → Includes incorrect Statement 3.
- �� Option D → Includes incorrect Statement 3.
Used
- Elimination
Application:
- Remove the statement contradicting energy-density equality.
Final Logic:
- Average electric and magnetic contributions are equal.
Half Electric, Half Magnetic
15 If the electric field is in the +y direction and the wave travels in the +x direction, the magnetic field is strictly defined.
1. The cross product requires B to be in the +z direction
2. The cross product ĵ × k̂ = î satisfies the condition
3. The magnetic field aligns with the x-axis
4. The electric field aligns with the z-axis
�� Propagation direction = E × B. �� ĵ × k̂ = î. �� B must point along +z.
Given: E along +y Propagation along +x Since: E × B = Propagation Direction ĵ × B = î Therefore: B = k̂ Statements 1 and 2 are correct. Statements 3 and 4 are incorrect.
- �� Option B → Both statements are incorrect.
- �� Option C → Statement 3 is incorrect.
- �� Option D → Statement 4 is incorrect.
Used
- Vector Analysis
Application:
- Apply the right-hand rule to E × B.
Final Logic:
- ĵ × k̂ = î.
j × k = i
16 To ensure the logical consistency of Maxwell's equations, it was found that the fields inside a parallel plate capacitor demonstrate orthogonality.
1. The electric field is perpendicular to the plates.
2. The magnetic field circles parallel to the plates.
3. B and E are entirely parallel.
4. The displacement current induces a parallel electric field.
�� Electric field exists between plates. �� Magnetic field forms circular loops. �� E and B are not parallel.
Inside a charging capacitor: • Electric field is perpendicular to the plates. • Displacement current produces magnetic field lines that circle around the axis, parallel to the plates. Thus Statements 1 and 2 are correct. Statements 3 and 4 are incorrect.
- �� Option B → Statement 3 is incorrect.
- �� Option C → Statement 3 is incorrect.
- �� Option D → Statements 3 and 4 are incorrect.
Used
- Concept Recall
Application:
- Use the capacitor model discussed by Maxwell.
Final Logic:
- E and B remain mutually perpendicular.
Capacitor: E Through, B Around
17 If a wave possesses a frequency of 10⁹ Hz, what is the wavelength of the electromagnetic wave produced?
(c = 3 × 10⁸ m/s)
�� λ = c/f. �� Use vacuum speed of light. �� Substitute values.
λ = c/f = (3 × 10⁸)/(10⁹) = 0.3 m Hence Option A is correct.
- �� Option B → Corresponds to 10⁸ Hz.
- �� Option C → Corresponds to 10⁷ Hz.
- �� Option D → Corresponds to 10¹⁰ Hz.
Used
- Substitution
Application:
- Apply λ = c/f.
Final Logic:
- λ = 0.3 m.
10⁹ Hz → 0.3 m
18 Because of the strong experimental backing of the constant velocity of EM waves in vacuum, the scientific community
�� c is a universal constant. �� The metre is defined using c. �� Modern SI units depend on fixed constants.
The modern definition of the metre is based on the distance traveled by light in vacuum during a specified fraction of a second. Thus the fixed value of c is used to define length standards. Therefore Option A is correct.
- �� Option B → Scientific standards rely on velocity definitions.
- �� Option C → Not scientific.
- �� Option D → Time is not defined using magnetic amplitudes.
Used
- Concept Recall
Application:
- Recall the SI definition of the metre.
Final Logic:
- Length standards are based on c.
Metre Defined by Light
19 Photon scales:
�� Photon energy depends on frequency. �� E = hν. �� Higher frequency means higher energy.
Planck's relation states: E = hν Thus photon properties are fundamentally linked through energy and frequency. Therefore Option A is correct.
- �� Option B → Not Planck's relation.
- �� Option C → Irrelevant photon properties.
- �� Option D → Not physical photon scales.
Used
- Concept Recall
Application:
- Recall Planck's quantum hypothesis.
Final Logic:
- Energy is directly proportional to frequency.
E = hν
20 Match List I with List II
| List I | List II |
|---|---|
| 1. Ultraviolet rays | a. 400 nm to 1 nm |
| 2. Infrared waves | b. 1 mm to 700 nm |
| 3. Gamma rays | c. < 10⁻³ nm |
| 4. Microwaves | d. 0.1 m to 1 mm |
�� UV lies below visible wavelengths. �� Infrared lies above visible wavelengths. �� Gamma rays have the shortest wavelengths.
Ultraviolet rays have wavelengths shorter than visible light, typically from 400 nm to 1 nm. Infrared waves have wavelengths longer than visible light, ranging from 700 nm to 1 mm. Gamma rays possess the shortest wavelengths in the electromagnetic spectrum, generally less than 10⁻³ nm. Microwaves occupy the region between radio waves and infrared waves, with wavelengths from 0.1 m to 1 mm. Therefore: 1 → a 2 → b 3 → c 4 → d Hence, Option A is correct.
- �� Option B → All wavelength regions are mismatched.
- �� Option C → UV and IR are interchanged.
- �� Option D → Microwave and infrared regions are interchanged.
Used
- Option Grouping
Application:
- Match each EM-wave type to its standard wavelength range.
Final Logic:
- Standard electromagnetic spectrum ordering determines the answer.
Gamma < UV < Visible < IR < Microwave
