AIIMS Physics Electromagnetic Waves Class 12 Questions

For a toroid N = 500, radius = 40 cm, and area of cross section = 10 cm². Find inductance.

In a transformer, numbers of turns in the primary are 140 and that in the secondary are 280. If current in primary is 4 A, then that in the secondary is.

If maximum energy is stored in capacitor at t = 0 then find the time after which current in the circuit will be maximum.

A proton is projected with velocity $\vec{\text{V}} = 2\hat{\text{i}}$ in a region where magnetic field $\vec{\text{B}} = \left(\hat{\text{i}} + 3\hat{\text{j}} + 4\hat{\text{k}}\right)\mu\text{T}$ and electric field $\vec{\text{E}} = 10\hat{\text{i}}\ \mu\text{V/m}$. Then find out the net acceleration of proton:

In an LCR series circuit, the source voltage is $120\text{ volt}$, the voltage across the inductor is $50\text{ volt}$, and across the resistor is $40\text{ volt}$. Determine the voltage across the capacitor.

Ratio of electric and magnetic field due of moving point charge if its speed is 4.5×10⁵ m/s

In toroid magnetic field on axis will be the radius = 0.5 cm, current = 1.5A, turns = 250, permeability = 700.

A toroid having average diameter 2.5 m, number A turns 400, current = 2A and magnetic field has 10 T what will be induced magnetic field (in amp/m)

Assertion: For communication antenna length should be comparable to λ. (ℓ ∼ λ) Reason: It leads to maximum power

Assertion: If a charged particle is released from rest in a region of uniform electric and magnetic fields parallel to each other, it will move in a straight line. Reason: The electric field exerts no force on the particle but the magnetic field does.

A wire is bent in the form of a ring of diameter $2a$ having self-inductance $L$, then $L$ will depend upon $a$ as:

If in a solenoid, a rod of relative permeability $\mu_r$ is kept, then find the self-inductance of the solenoid (where $N =$ number of turns, $l =$ length of solenoid and $A =$ area of solenoid).

The fundamental radio antenna is a metal rod which has a length equal to

In terms of basic units of mass (M), length (L), time (T) and charge (Q), the dimensions of magnetic permeability of vacuum (μ₀) would be

In a series RC circuit having battery of 12 V, capacitor is charged from 0 to 6 V in 0.1 s. Find value of resistance R.

In an Oscillation of L-C circuit, the maximum charge on the capacitor is $Q$. The charge on the capacitor when the energy is stored equally between the electric and magnetic field is

A wire having mass m and length l can freely slide on a pair of parallel smooth horizontal rails placed in vertical magnetic field B. The rails are connected by a capacitor of capacitance C. The electric resistance of the rails and the wire is zero. If a constant force F acts on the wire as shown in the figure. Then, the acceleration of the wire can be given as

Find the average energy density corresponding to maximum electric field, if magnetic field in a plane electromagnetic wave is given by B = 200 × 10⁻⁶ sin[(4 × 10¹⁵)(t − x/c)]

Assertion : When number of turns in a coil is doubled, coefficient of self-inductance of the coil become four times. Reason : This is because $L \propto N^2$.

Assertion: The velocity of electromagnetic waves depends on electric and magnetic properties of the medium. Reason: Velocity of electromagnetic waves in free space is constant.

Assertion: The frequency of circular motion of a charged particle in cyclotron is independent of the mass of the particle. Reason: Greater the mass of the particle less will be the frequency of the particle.

Assertion: Cyclotron does not accelerate electron. Reason: Mass of the electron is very small.

Assertion: The electromagnetic waves are transverse in nature. Reason: Waves of wavelength 10 μm are radiowave and microwave.

Assertion: When a charge particle moves in a circular path. It produces electromagnetic wave. Reason: Charged particle has acceleration.

Assertion (A) A charge moving in a circular orbit can produce electromagnetic wave. Reason (R): The source of an electromagnetic wave should be in accelerated motion.

Assertion Static crashes are heard on radio, when lightning flash occurs in the sky. Reason Electromagnetic waves having frequency of radiowave range, interfere with radiowaves.

Which of the following is the best method to reduce eddy currents?

Two solenoids of equal number of turns having their length and the radii in the same ratio 1 : 2. The ratio of their self-inductance will be

Assertion: Electromagnetic radiations exert pressure. Reason: Electromagnetic-waves carry both momentum and energy.

The frequency order for X⁻rays (A), γ-rays (B), UV rays (C) is

Assertion: In electromagnetic waves electric field and magnetic field lines are perpendicular to each other. Reason: Electric field and magnetic field are self sustaining.

Magnetic energy per unit volume is represented by

The area covered by a transmitting antenna of height 50 m is

Assertion: An electric field is preferred in comparison to magnetic field for detecting the electron beam in a television picture tube. Reason: Electric field requires low voltage.

Assertion: Electromagnetic waves are transverse in nature. Reason: The electric and magnetic fields of an e.m. wave are perpendicular to each other and also perpendicular to the direction of wave propagation.

Light with an energy flux of 18 W/cm² falls on a non-reflecting surface at normal incidence. The pressure exerted on the surface is

A coil of wire of a certain radius has 100 turns and a self inductance of 15 mH. The self inductance of a second similar coil of 500 turns will be

If v₁, v₂ and v₃ are the speeds of gamma rays, X⁻rays and microwaves respectively in vacuum, then

Assertion : Transformers are used only in alternating current source not in direct current. Reason : Only a.c. can be stepped up or down by means of transformers.

Assertion : The dimensional formula for product of resistance and conductance is same as for dielectric constant. Reason : Both have dimensions of time constant.

In an electrical circuit containing L, C and R which of the following does not denote the dimensions of frequency?

The velocity of electromagnetic radiation in a medium of permittivity ε₀ and permeability μ₀ is given by

Assertion: The alternating current lags behind the e.m.f. by a phase angle of π/2, when AC flows through an inductor. Reason: The inductive reactance increases as the frequency of AC source decreases.

Assertion: A spark occur between the poles of a switch when the switch is opened. Reason: Current flowing in the conductor produces magnetic field.

Assertion: Inductance coils are usually made of thick copper wire. Reason: Induced current is more in wire having less resistance.

In the following diagram, which particle has highest e/m value?

What is the dimensions of impedance ?

Assertion : Dipole oscillations produce electromagnetic waves. Reason : Accelerated charge produces electromagnetic waves.

Assertion : Electromagnetic waves with frequencies smaller than the critical frequency of ionosphere cannot be used for communication using sky wave propagation. Reason : The refractive index of the ionosphere becomes very high for frequencies higher than the critical frequency.

Assertion : An emf E is induced in a closed loop where magnetic flux is varied. The induced E is not a conservative field. Reason : The line integral E⋅dl around the closed loop is non-zero.