4th Class Computers Science Computer and Its Peripherals Modem

         Modem  

A modem is a device attached to the computers that can convert digital signals to analog signal and vice- versa. Digital signal is a group of discrete electronic units that are transmitted in rapid succession and an analog signal consists of continuous electrical waves. Modem is a short name for modulator-demodulator, where modulator can convert digital signals to analog signals and demodulator does the opposite. Modem is a device that enables computers, fax machines and other equipment to communicate with each other across telephone lines or over cable television network cables. Since telephone cables can carry analog signals, the computer generated digital signal is first converted into analog form so that it can be carried by telephone lines. Upon receiving it, the modem at receiver end can understand it. Modems transmit data at different speeds, measured by the number of bits of data they send per second (bps). Examples of modem speeds are: 256 Kbps, 512 Kbps, 2mbps, etc.  

 Given below are the statements about MODEM. Select the correct statements.

1. A modem is a device attached to the computers that can convert analog signal to digital signals and vice-versa.

2. An analog signal is a group of discrete electronic units that are transmitted in rapid succession.

3. Digital signal consists of continuous electrical waves.

(A) Only 1                                                           

(B) 2 and 3

(C) 1 and 3                                          

(D) All of these

(E) None of these.  

Answer: (a)

Explanation

Correct Option:

(A) Only statement 1 is correct about MODEM.

Incorrect Options:

(B) Statements 2 and 3 are incorrect about MODEM. Therefore, option (B) is incorrect,

(C) Statement 1 is correct but statement 3 is incorrect. Therefore, option (C) is incorrect.

(D) All the given statements are not correct. Therefore, option (D) is incorrect.

(E) All the given statements are not incorrect. Therefore, option (E) is incorrect.    

 Fill in the blanks:

1. Modulator can convert ____ signals to ____ signals.

2. Demodulator convert ____ signals to ____ signals.

3. Modems transmit data at different speeds, which are measured in ______.

(A) Analog, Digital, Digital, Analog, Bit per second

(B) Digital, Analog, Digital, Analog, Byte per second

(C) Digital, Analog, Analog, Digital, Bit per second

(D) Digital, Analog, Digital, Analog, Bit per minutes

(E) Digital, Analog, Analog, Digital, Data per second

Answer: (c)

Explanation

Correct Option:

(C) Options given in (C) are correct.

Incorrect Options:

(A) Options given in (A) are incorrect. Therefore, option (A) is incorrect.

(B) Options given in (B) are incorrect. Therefore, option (B) is incorrect.

(D) Options given in (D) are incorrect. Therefore, option (D) is incorrect.

(E) Options given in (E) are incorrect. Therefore, option (E) is incorrect.