# Issues with Low Frequency

## Trending Questions

**Q.**An electro-magnetic wave is propagating in a medium with a velocity →v= v ˆi . The instantaneous oscillating electric field of this electromagnetic wave is along +y axis. Then, the direction of oscillating magnetic field of the electromagnetic wave will be along

- –z direction
- +z direction
- –y direction
- –x direction

**Q.**The bit rate for a signal, which has a sampling rate of 8 kHz and where 16 quantisation levels have been used is

- 64000 bits/sec
- 16000 bits/sec
- 72000 bits/sec
- 32000 bits/sec

**Q.**Which of the following relations is correct with regards to electric and magnetic field oscillation vector in case of EM waves (wave is propagating in the x direction)?

- ∂E∂x=∂B∂t
- ∂E∂x=−∂B∂t
- ∂E∂t=∂B∂xμ0ε0
- ∂E∂t=−∂B∂xμ0ε0

**Q.**The poynting vector for an electromagnetic wave is :

- →S=→E×→H
- →S=→E×→B
- →S=(→E×→H)/2
- →S=(→E×→B)/2

**Q.**The electric field associated with an e.m. wave in vacuum is given as →E=40cos(kz−6×108t)^i, where all quantities are in SI units. The value of the propagation constant k is,

- 6 m−1
- 3 m−1
- 2 m−1
- 0.5 m−1

**Q.**If n1, n2, n3 be the frequency of the segments of a stretched string, then the frequency n of the string itself in terms of n1, n2 and n3 is

- (n1n2+n2n3+n1n3)n1n2n3
- (n1n2+n3n1)n1n2n3
- n1n2n3(n1n2+n2n3+n3n1)
- n1n2n3(n1n2+n3n1)

**Q.**In a half wave rectifier, the r.m.s. value of the a.c. component of the wave is

- equal to d.c. value
- more than d.c. value
- less than d.c. value
- zero

**Q.**A tuning fork produces 4 beats/second from the stretched string of a sonometer of length 0.49 m and 0.50 m. Calculate the frequency of the tuning fork.

**Q.**An EM wave from the air enters a medium. The electric field are

−→E1=E01 ^x cos[2πf(zc−t)]

in air and −→E2=E02 ^x cos [k(2z−ct)]

in medium, where the wave number k and frequency f refer to the values in air. The medium is non-magnetic. If ϵr1 and ϵr2 refer to relative permittivities of air and the medium, which of the following options is correct?

- ϵr1ϵr2=4
- ϵr1ϵr2=2
- ϵr1ϵr2=14
- ϵr1ϵr2=12

**Q.**A ________ filter significantly attenuates all frequencies below fc and passes all frequencies above fc :

- band-pass
- high-pass
- low-pass
- band-low

**Q.**An EM wave from air enters a medium. The electric fields are −→E1=E01 ^x cos[2πf(zc−t)] in air and −→E2=E02 ^x cos[k(2z−ct)] in medium, where the wave number k and frequency f refer to their values in air. The medium is non-magnetic. If εr1 and εr2 refer to relative permittivities of air and medium respectively, which of the following options is correct?

- εr1εr2=4
- εr1εr2=2
- εr1εr2=14
- εr1εr2=12

**Q.**A wave pulse passing on a string with a speed of 40 cm s−1 in the negative x-direction has its maximum at x = 0 at t = 0. Where will this maximum be located at t = 5 s?

**Q.**The bit rate for a signal, which has a sampling rate of 8 kHz and where 16 quantisation levels have been used is

- 32000 bits/sec
- 16000 bits/sec
- 64000 bits/sec
- 72000 bits/sec

**Q.**The energy of the wave that passes through unit area unit time is called as ......................... .

- Quality
- Intensity
- Pitch
- Amplitude

**Q.**A wave disturbance in a medium is described by y(x, t)=0.02cos(50πt+π2)cos(10πx) where x and y are in meters and t in seconds

- A displacement node occurs at x=0.15m
- An antinode occurs at x=0.3m
- The wavelength of the wave is 0.2m
- The speed of the wave is 5.0m/s

**Q.**The particle acceleration in a transverse wave is

- same as wave acceleration.
- related to particle velocity.
- is related to particle position.
- is always zero.

**Q.**Wave velocity and particle velocity at any instant between t=0 to t=T/4 Iin a progressive wave will be

- perpendicular to each other
- parallel to each other
- changes abruptly
- none of the above

**Q.**Particle acceleration in a travelling transverse wave is always is

- always parallel to particle velocity
- always anti-parallel to particle velocity
- can be parallel or anti-parallel to particle velocity
- None of these

**Q.**Two pules travelling on the same string are described by

y1=5(3x−4t)2+2 and y2=−5(3x+4t−6)2+2

marks the correct statement (s)

- The direction in which each pulse is travelling y1 is in positive x-axis, y2 is in negative x-axis.
- The time when the two waves cancel everywhere is 0.75 sec.
- The point where the two waves always cancel is x=1m
- Amplitude is different for two waves

**Q.**Find the number of times intensity is maximum in time interval of 1 sec.

- 4
- 6
- 8
- 10