Tag: physics

Quizzes (598) Questions (13441)

Questions Related to physics

Multiple choice physics reflection of light and shadow regular and irregular reflection regular and diffused reflection laws of reflection

Which surfaces are said to be smooth?

  1. As long as the irregularities of surfaces are small as compared to the wavelength of the incident light.

  2. As long as surface irregularities are large compared to the wavelength of the incident light.

  3. As long as surface smoothness are small as compared to wavelength of reflected light

  4. As long as the surface irregularities are large as compared to the wavelength of reflected light.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A surface behaves as a smooth surface as long as the surface irregularities are small compared with the wavelength of the incident light.

Multiple choice physics reflection of light and shadow regular and irregular reflection regular and diffused reflection laws of reflection

The change in reflected wave, when light wave suffers reflection at the interface from air to glass is?

  1. $0$

  2. $\dfrac{\pi}{2}$

  3. $\pi$

  4. $2\pi$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
When light wave suffers reflection at the interface from air to glass, the change in phase of the reflected wave is equal to π
Hence the option C is the right answer
Multiple choice physics reflection of light and shadow regular and irregular reflection regular and diffused reflection laws of reflection

The reflection taking place from the walls of a building is called:

  1. regular reflection

  2. diffused reflection

  3. multiple reflection

  4. internal reflection
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The reflection taking place from the walls of a building is called diffused reflection.
In diffused reflection, the reflected rays are not parallel to each other. This kind of reflection occurs from a coarse surface. Walls of a building being coarse surfaces, give rise to diffused reflections.

Multiple choice physics communication system elements of a communication system elements of communication system electromagnetic waves and communication system

The wave used by artificial satellites for communication is

  1. Microwaves

  2. Infrared rays

  3. Radio rays

  4. X-rays
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Microwaves are mostly used for satellite communication, as microwaves can pass straight through the atmosphere and connect antennas on earth to satellite in earth's orbit.

Multiple choice physics communication system elements of a communication system elements of communication system electromagnetic waves and communication system

The critical velocity of satellite of mass $100 kg$ moving round a planet is $20 m/s$. If another satellite of mass $200 kg$ is kept moving in the same orbit then its critical velocity will be:

  1. $40 km/hr$

  2. $72 km/hr$

  3. $40 m/s$

  4. $72 m/s$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The critical velocity (orbital velocity) of a satellite is given by v = sqrt(GM/r). It is independent of the mass of the satellite. Therefore, the velocity remains 20 m/s. Converting 20 m/s to km/hr: 20 * (3600/1000) = 72 km/hr.

Multiple choice physics communication system elements of a communication system elements of communication system electromagnetic waves and communication system

In sky wave communication which of the frequency will be reflected back by the ionospheric layer having electron density $4 \times 10 ^ { 6 } / \mathrm { m } ^ { 3 }$

  1. $19 \times 10 ^ { 3 } \mathrm { Hz }$

  2. $9 \times 10 ^ { 3 } H z$

  3. $31 \times 10 ^ { 3 } \mathrm { Hz }$

  4. $20 \times 10 ^ { 3 } \mathrm { Hz }$
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice physics communication system elements of a communication system elements of communication system electromagnetic waves and communication system

A digital signal

  1. is less reliable than analog signal

  2. is more reliable than analog signal

  3. is equally reliable as the analog signal

  4. Not at all reliable
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Noise is added to digital signal also but its easier to remove the noise and amplify the digital signals as compared to analog signals, because analog signals contain many frequencies.

Multiple choice physics communication system elements of a communication system elements of communication system electromagnetic waves and communication system

Statement A: If the antenna is vertical,a vertically polarised EM wave is radiated
Statement B: The vertically polarised EM wave has electrical variations in the vertical plane

  1. A is true but B is false

  2. A is false but B is true

  3. A and B are false

  4. A and B are true
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Polarization of wave depends upon the orientation of the antenna. direction of polarization is along the orientation of antenna. By convention, direction of polarization of an EM wave is along the variation of electric field.