Physics Test 84

Result

Physics Test 84

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Weekly Quiz Competition

Question 1
4 / -1

The output of an OR gate is connected to both the inputs of a NAND gate. The combination will serve as a :

A
OR gate

B
NOT gate

C
NOR gate

D
AND gate
Question 2
4 / -1

Which of the following four alternatives is not correct we need modulation :-

A
To increase the selectivity

B
To reduce the time log between transmission and reception of the information signal

C
To reduce the size of antenna

D
To reduce the fractional band width, that is the ratio of the signal band width to the centre of frequency

Solution

As We know that

Need of modulation :-

1. Reduce the fractional band with, that is the ratio of the signal band width to the centre frequency.

2. Increase the selectivity.

3. Reduce the size of antenna.

So, option (2) is not correct.
Question 3
4 / -1

Broad casting antennas are generally :-

A
Both vertical and horizontal type

B
Horizontal type

C
Omnidirectional type

D
Vertical type

Solution

A broadcasting antenna is used for receiving as broadcasting radio waves in all horizontal and vertical directions equally.

Option (1) is correct.
Question 4
4 / -1

Which of the following statement is NOT Correct?

A
The critical frequency of an ionospheric layer is the highest frequency that will be reflected back by the layer when it is vertically incident

B
Electromagnetic waves of frequencies higher than about 30 MHz can not penetrate the ionosphere

C
Sky waves signals in the broadcast frequency range are stronger at night than in the day time.

D
Ground wave signals are more stable than the sky wave signals.

Solution

Option (2) is not correct.

Because the radio frequencies above 30 MHz has the tendency to penetrate the ionosphere making them unsuitable for long distance propagation. So, the range of frequencies from 30 to 300 MHz (also MHz and above) which are placed under the very high frequency (VHF) category are mainly used for the line of sight communication.
Question 5
4 / -1

Which of the following modulated signal has the best noise – tolerance?

A
Short Wave

B
Medium – Wave

C
Long Wave

D
Amplitude – Modulated

Solution

Short Wave has the best noise tolerance.