List of practice Questions

Let K₁ and K₂ be the maximum kinetic energies of photo-electrons emitted when two monochromatic beams of wavelength λ₁ and λ₂, respectively are incident on a metallic surface. If λ₁= 3λ₂ then:

A transverse wave is represented by $y = 2sin(ωt – kx)$ $cm$. The value of wavelength (in cm) for which the wave velocity becomes equal to the maximum particle velocity, will be

Match List-I with List-II.

List - I		List - II
A.	Television signal	i.	03 KHz
B.	Radio signal	ii.	20 KHz
C.	High Quality Music	iii.	02 MHz
D.	Human speech	iv.	06 MHz

Choose the correct answer from the options given below:

A set of 20 tuning forks is arranged in a series of increasing frequencies. If each fork gives 4 beats with respect to the preceding fork and the frequency of the last fork is twice the frequency of the first, then the frequency of last fork is _______ Hz

Two travelling waves of equal amplitudes and equal frequencies move in opposite directions along a string. They interfere to produce a stationary wave whose equation is given by $y = (10 cos \ \pi x\ sin \frac {2\pi t}{T})$ cm. The amplitude of the particle at $x = \frac 43$ cm will be _______ cm.

A wire of length 30 cm, stretched between rigid supports, has it’s n^th and (n + 1)^th harmonics at 400 Hz and 450 Hz, respectively. If tension in the string is 2700 N, its linear mass density is _____ kg/m.

The frequency of echo will be _______ Hz if the train blowing a whistle of frequency 320 Hz is moving with a velocity of 36 km/h towards a hill from which an echo is heard by the train driver. Velocity of sound in air is 330 m/s.

The magnetic field of a plane electromagnetic wave is given by $\vec{ B }=2 \times 10^{-8} \sin \left(05 \times 10^3 x +15 \times 10^{11} t \right) \hat{ j } T$ The amplitude of the electric field would be

A plane of electromagnetic waves travels in a medium with a relative permeability of 1.61 and relative permittivity of 6.44. If the magnitude of magnetic intensity is 4.5 × 10^–2 Am^–1at a point, what will be the approximate magnitude of electric field intensity?(Given: Permeability of free space μ₀ = 4π × 10^–7 NA^–2, speed of light in vacuum c = 3 × 10⁸ ms^–1)

A baseband signal of 3.5 MHz frequency is modulated with a carrier signal of 3.5 GHz frequency using amplitude modulation method. What should be the minimum size of antenna required to transmit the modulated signal?

Match List I with List II

	List I		List II
A	Facsimile	I	Static Document Image
B	Guided media Channel	II	Local Broadcast Radio
C	Frequency Modulation	III	Rectangular wave
D	Digital Single	IV	Optical Fiber

The electric field in an electromagnetic wave is given by $E = 56.5\ sin ω(t – \frac xc)\ NC^{–1}$. Find the intensity of the wave if it is propagating along x-axis in the free space. (Given $∈_0 = 8.85 × 10^{–12} C^2N^{–1}m^{–2}$)

Which is the correct ascending order of wavelengths?

A sinusoidal wave y(t) = 40sin(10 × 10⁶ πt) is amplitude modulated by another sinusoidal wave x(t) = 20sin(1000πt). The amplitude of minimum frequency component of modulated signal is:

An EM wave propagating in x-direction has a wavelength of 8 mm. The electric field vibrating y-direction has maximum magnitude of 60 Vm^–1. Choose the correct equations for electric and magnetic field if the EM wave is propagating in vacuum:

The magnetic field of a plane electromagnetic wave is given by:
$\vec B=2×10^{−8}sin⁡(0.5×10^3x+1.5×10^{11}t)\hat jT$.
The amplitude of the electric field would be

A radar sends an electromagnetic signal of electric field (E₀) = 2.25 V/m and magnetic field (B₀) = 1.5 × 10^–8 T which strikes a target on line of sight at a distance of 3 km in a medium. After that, a part of signal (echo) reflects back towards the radar with same velocity and by same path. If the signal was transmitted at time t = 0 from radar, then after how much time echo will reach to the radar?

The TV transmission tower at a particular station has a height of 125 m. For doubling the coverage of its range, the height of the tower should be increased by

Sun light falls normally on a surface of area $36 cm^2$ and exerts an average force of $7.2 × 10^{–9} N$ within a time period of $20 minutes$. Considering a case of complete absorption, the energy flux of incident light is

If electric field intensity of a uniform plane electromagnetic wave is given as
$E = -301.6 \sin(kz - \omega t) \hat{a}_x + 452.4 \sin(k\omega - \omega t) \hat{a}_y \, \frac{V}{m}$
Then, magnetic intensity ‘H’ of this wave in Am^–1 will be :
[Given : Speed of light in vacuum c = 3 × 10⁸ms^–1, Permeability of vacuum $\mu_0 = 4\pi \times 10^{-7}$ NA^–2]

In free space, an electromagnetic wave of 3 GHz frequency strikes over the edge of an object of size $\frac{\lambda}{100}$, where λ is the wavelength of the wave in free space. The phenomenon, which happens there will be

Identify the correct statements from the following descriptions of various properties of electromagnetic waves.
(A) In a plane electromagnetic wave electric field and magnetic field must be perpendicular to each other and direction of propagation of wave should be along electric field or magnetic field.
(B) The energy in electromagnetic wave is divided equally between electric and magnetic fields.
(C) Both electric field and magnetic field are parallel to each other and perpendicular to the direction of propagation of wave.
(D) The electric field, magnetic field and direction of propagation of wave must be perpendicular to each other.
(E) The ratio of amplitude of magnetic field to the amplitude of electric field is equal to speed of light.

Choose the most appropriate answer from the options given below

With reference to the observations in photo-electric effect, identify the correct statements from below:
(A) The square of maximum velocity of photoelectrons varies linearly with frequency of incident light.
(B) The value of saturation current increases on moving the source of light away from the metal surface.
(C) The maximum kinetic energy of photo-electrons decreases on decreasing the power of LED (Light emitting diode) source of light.
(D) The immediate emission of photo-electrons out of metal surface can not be explained by particle nature of light/electromagnetic waves.
(E) Existence of threshold wavelength can not be explained by wave nature of light/electromagnetic waves.

Choose the correct answer from the options given below.

A square wave of the modulating signal is shown in the figure. The carrier wave is given by C(t) = 5 sin(8πt) Volt. The modulation index is

A beam of light travelling along X-axis is described by the electric field E_y = 900sin ω(t – x/c). The ratio of electric force to magnetic force on a charge q moving along Y-axis with a speed of 3 × 10⁷ ms^–1 will be :
(Given speed of light = 3 × 10⁸ ms^–1)