Source of EM Waves

Q. The energy of the electromagnetic waves is of the order of $15keV$. To which part of the spectrum does it belong?

1. $\gamma$ - rays
2. X-rays
3. Infrared rays
4. Ultraviolet rays

Q.

A beam of light consisting of two wavelengths, 650 nm and 520 nm, is used to obtain interference fringes in a Young’s double-slit experiment.

(a) Find the distance of the third bright fringe on the screen from the central maximum for wavelength 650 nm.

(b) What is the least distance from the central maximum where the bright fringes due to both the wavelengths coincide?

Q.

The frequency (v) of charged particle, moving at right angles to the magnetic field is independent of

1. magnetic induction (B)

2. radius of circular trajectory (r)

3. speed of the particle (v)

4. both speed of the particle (v) and radius of trajectory (r).

Q. A beam of monochromatic blue light of wavelength $4200A^{\circ }$ in air travels in water $\mu =\frac{4}{3}$. Its wavelength in water will be

1. $2800A^{\circ }$
2. $5600A^{\circ }$
3. $3150A^{\circ }$
4. $4000A^{\circ }$

Q. A charged particle oscillates about its mean equilibrium positionwith a frequency of 109 Hz. What is the frequency of the electromagnetic waves produced by the oscillator?

Q. Out of the following options, which one can be used to produce a propagating electromagnetic wave?

1. A stationary charge
2. A chargeless particle
3. An accelerating charge
4. A charge moving at constant velocity

Q. The source of electromagnetic waves can be a charge -

1. falling freely in an electric field.
2. moving in a circular orbit with constant speed.
3. Both options $\left(A\right)$ and $\left(B\right)$
4. None of these

Q. A uniform electric field of intensity E = 10^6 V/m exist in vertically downwards direction in a region. A particle of mass m = 0.01 kg and charge q= 10^-6C is suspended by an inextensible thread of length I= Im. The particle is displaced slightly from its mean position and released. Calculate the time period of its oscillation. What minimum velocity should be given to the particle at rest from its equilibrium position so that it completes a full circle in vertical plane? Calculate the maximum and minimum tension in the thread in its circular motion in vertical plane. [

Q.

Production of the electromagnetic waves is demonstrated by:

Q.

Which part of the sun’s energy is responsible for drying clothes?

1. Visible lights

2. Ultraviolet radiations

3. Infrared radiations

4. None of these

Q.

The rms value of the electric field of the light coming from sun is 720 N/C. The average energy density of the EM wave is

1. $3.3\times {10}^{-3}J/m^3$

2. $4.58\times {10}^{-6}J/m^3$

3. $6.37\times {10}^{-9}J/m^3$

4. $81.35\times {10}^{-12}J/m^3$

Q.

Cathode rays are a beam of fast moving electrons.

1. True
2. False

Q.

If light is a electromagnetic wave, will it get deflected near a magnet ?

Q.

Arrange the following electromagnetic wave in the order of their increasing wavelength:

(a) $\gamma$-rays

(b) Microwaves

(c) X-rays

(d) Radio waves

How are infra-red waves produced? What role does infra-red radiation play in (i) maintain the Earth’s warmth and (ii) physical therapy?

Q. Name the electromagnetic radiations used for (a) water purification, and (b) eye surgery.

Q.

Does the nature of EM wave depend on the magnitude of acceleration of the charged particle?

Q. Which of the following are electromagnetic waves?
(a) α-rays
(b) Beta-plus rays
(c) Beta-minus rays
(d) Gamma rays

Q. -q charge is oscillationg along equatorial plane . two fixed charges are +Q are present on axial plane . calculate time period

Q. Which one of the following is the primary effect of UV radiation caused due to depletion of ozone layer?

1. Heart attack
2. Skin cancer
3. High fever
4. All of these
5. None of these

Q. Which of the following gives the basis for the observation that the universe is expanding?

1. The fact that every element of atomic number greater than 83 is radioactive
2. Newton's law of universal gravitation
3. Red shift of light from other galaxies
4. The zeroth law of thermodynamics
5. Mass-energy equivalence

Q. Light of 630 nm produces fringes of fringe width 8.31 nm. A second wavelength gives fringes of fringe width 7.61 nm. What is its wavelength?

1. 451 nm
2. 523 nm
3. 577 nm
4. 653 nm

Q.

The rms value of the electric field of the light coming from sun is 720 N/C. The average energy density of the EM wave is

1. $3.3\times {10}^{-3}J/m^3$

2. $4.58\times {10}^{-6}J/m^3$

3. $6.37\times {10}^{-9}J/m^3$

4. $81.35\times {10}^{-12}J/m^3$

Q. Which of the following statement is wrong ?

1. A changing magnetic field produces an electric field.
2. A changing electric field produces a magnetic field.
3. A charged particle in a uniform motion produces electromagnetic wave.
4. Energy density in E. M. waves is equally divided among both fields.

Q.

Which of the following is used in communication technology:

1. X-Ray

2. Gamma ray

3. Microwaves

4. Ultraviolet ray

Q. Which of the following properties is not exhibited by X-rays?

1. Interference
2. Polarisation
3. Diffraction
4. Deflection by electric field.

Q. An electromagnetic wave can be created by accelerating charge.

1. False
2. True

Q.

Which radiation in sunlight, causes heating effect

1. Ultraviolet

2. Infrared

3. Visible light

4. All of these

Q.

Which of the following component of EM wave spectrum is the least energetic:

1. Infrared ray

2. X-Ray

3. Gamma ray

4. Ultraviolet ray

Q. The X-ray beam emerging from an X-ray tube
(a) is monochromatic
(b) has all wavelengths smaller than a certain maximum wavelength
(c) has all wavelengths greater than a certain minimum wavelength
(d) has all wavelengths lying between a minimum and a maximum wavelength

Q.

Which of the following are not electromagnetic waves

1. Cosmic rays
2. Gamma rays
3. Beta rays
4. X-rays