Arrange the following electromagnetic radiations per quantum in the order of increasing energy:
A: Blue light
B: Yellow light
C: X-ray
D: Radiowave
D, B, A, C
A, B, D, C
C, A, B, D
C, A, B, D
Choose the correct statement:
In amplitude modulation, the amplitude of the high-frequency carrier wave is made to vary in proportion to the amplitude of the audio signal.
In amplitude modulation, the frequency of the high-frequency carrier wave is made to vary in proportion to the amplitude of the audio signal.
In frequency modulation, the amplitude of the high-frequency carrier wave is made to vary in proportion to the amplitude of the audio signal.
In frequency modulation, the amplitude of the high-frequency carrier wave is made to vary in proportion to the amplitude of the audio signal.
A signal of 5 kHz frequency is amplitude modulated on a carrier wave of frequency 2 MHz. The frequencies of the resultant signal is/are:
2005 kHz, and 1995 kHz
2005 kHz, 2000 kHz and 1995 kHz
2000 kHz and 1995 kHz
2000 kHz and 1995 kHz
A train is moving on a straight track with speed 20 ms-1 .It is blowing its whistle at the frequency of 1000 Hz. The percentage change in the frequency heard by a person standing near the track as the train passes him is (speed of sound = 320 ms-1 ) close to :
6%
12%
18%
18%
A diode detector is used to detect an amplitude modulated wave of 60% modulation by using a condenser of capacity 250 pico farad in parallel with a load resistance 100 kilo ohm. Find the maximum modulated frequency which could be detected by it.
10.62 MHz
10.62 kHz
5.31 mHz
5.31 mHz
B.
10.62 kHz
The frequency is given as
μ =0.6
R = 100 k = 100 x1000 Ω
c = 250 pico farad = 250 x 10-12 F
So,
A radar has a power of 1 Kw and is operating at a frequency of 10 GHz. It is located on a mountain top of height 500 m. The maximum distance upto which it can detect object located on the surface of the earth (Radius of earth = 6.4 x 106 m) is
80 km
16 km
40km
40km
This question has Statement 1 and Statement 2. Of the four choices given after the statements, choose the one that best describes the two statements.
Statement 1 - Sky wave signals are used for long distance radio communication. These signals are in general, less stable than ground wave signals.
Statement 2- The state of ionosphere varies from hour to hour, day to day and season to season.
Statement 1 is true, statement 2 is false.
Statement 1 is true, Statement 2 is true, Statement 2 is the correct explanation of Statement 1
Statement 1 is true, Statement 2 is true, Statement 2 is not the correct explanation of Statement 1
Statement 1 is true, Statement 2 is true, Statement 2 is not the correct explanation of Statement 1
A sound absorber attenuates the sound level by 20 dB. The intensity decreases by a factor of
1000
10000
10
10
In a full wave rectifier circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be
50 Hz
25 Hz
100 Hz
100 Hz
A telephonic communication service is working at carrier frequency of 10 GHz. Only 10% of it is utilized for transmission. How many telephonic channels can be transmitted simultaneously if each channel requires a bandwidth of 5 kHz?
2 x 106
2 x 105
2 x 104
2 x 105