✍️ Practice Section
Difficulty-wise problems with timer | Solve minimum 50 problems
Practice Timer
Level 1: Easy (CBSE/Boards)
Target Time: 2-3 minutes per question
An EM wave has frequency 750 THz. Calculate its wavelength.
Magnetic field amplitude in EM wave is 5×10⁻⁸ T. Find electric field amplitude.
Which EM wave has wavelength around 1 μm?
(A) Microwave (B) Infrared (C) Visible (D) UV
Light enters glass with n = 1.6. Find speed of light in glass.
Find energy of photon with wavelength 500 nm. (h = 6.6×10⁻³⁴ J·s)
When light goes from air to water, which does NOT change?
(A) Speed (B) Wavelength (C) Frequency (D) All change
What did Maxwell add to Ampere's law?
EM waves can travel through vacuum because:
(A) They have high energy
(B) Changing E creates B, changing B creates E
(C) They are transverse
(D) They are fast
In EM wave, E and B oscillate:
(A) In phase (B) 90° out of phase (C) 180° out of phase (D) Randomly
Which EM wave is used in microwave ovens?
Level 2: Moderate (NEET/JEE Main)
Target Time: 3-5 minutes per question
EM wave has E₀ = 90 V/m. Find average intensity. (ε₀ = 8.85×10⁻¹² C²/N·m²)
Light of intensity 15 W/m² falls on perfectly absorbing surface. Find radiation pressure.
In EM wave, E₀ = 60 V/m. Find total energy density.
Parallel plate capacitor is charged at 2 A. What is displacement current between plates?
Unpolarized light of intensity I₀ passes through polarizer. Find transmitted intensity.
Light of wavelength 600 nm in vacuum enters glass (n=1.5). Find wavelength in glass.
In EM wave, what fraction of total energy is in magnetic field?
Photon has energy 3×10⁻¹⁹ J. Find its momentum.
Intensity 10 W/m² falls on perfectly reflecting surface. Find radiation pressure.
Polarized light of intensity 100 W/m² passes through polarizer at 60°. Find output intensity.
Level 3: Advanced (JEE Advanced)
Target Time: 5-8 minutes per question
EM wave has B₀ = 4×10⁻⁷ T. Find: (a) E₀ (b) Average intensity (c) Radiation pressure on absorbing surface
Circular parallel plate capacitor (radius 5 cm) is charged. Electric field between plates changes at 10¹³ V/m·s. Find magnetic field at r = 3 cm from axis.
Displacement Current
Unpolarized light (I₀ = 80 W/m²) → Polarizer P₁ → Polarizer P₂ at 30° to P₁. Find final intensity.
Satellite (area 8 m², mass 500 kg) at Earth distance from Sun. Solar intensity = 1400 W/m². Surface perfectly reflecting. Find acceleration.
Light of wavelength 450 nm illuminates metal surface. Work function = 2 eV. Find: (a) Photon energy (b) Max KE of ejected electron
Practice Strategy
- Goal: Solve at least 50 problems from this chapter
- Distribution: 20 Easy + 20 Moderate + 10 Advanced
- Daily target: 5-7 problems with full solutions
- Review: Revisit incorrect problems after 2 days
- Time yourself: Build speed gradually