State TRUE or FALSE for the following. (i) A sine wave with a phase of 180°…
2017
State TRUE or FALSE for the following.
(i) A sine wave with a phase of 180° starts at time 0 with a zero amplitude. The amplitude is decreasing.
(ii) If a signal changes instantaneously, its frequency is zero.
(iii) In bipolar encoding, we use three voltage levels: positive, negative and zero.
(iv) Infrared signals can be used for short-range communication in a closed area using ground propagation.
- A.
(i) TRUE, (ii) FALSE, (iii) TRUE, (iv) FALSE
- B.
(i) TRUE, (ii) TRUE, (iii) TRUE, (iv) FALSE
- C.
(i) FALSE, (ii) TRUE, (iii) FALSE, (iv) FALSE
- D.
(i) TRUE, (ii) TRUE, (iii) FALSE, (iv) FALSE
Attempted by 7 students.
Show answer & explanation
Correct answer: A
The correct option is A.
(i) A 180o phase shift inverts a sine wave; at t=0, it starts at 0 and goes negative (amplitude decreases). (TRUE)
(ii) Instantaneous changes imply infinite frequency, not zero. (FALSE)
(iii) Bipolar encoding uses positive, negative, and zero volts. (TRUE)
(iv) Infrared uses line-of-sight propagation, not ground propagation. (FALSE)