Chapter 8, Digital Technology Video Solutions, Physics for the IB Diploma

Problem 1

Express the following decimal numbers as binary numbers:
(a) 3 ;(b) 10 ;(c) 18 ;(d) 31.
For each, state the most significant bit and least significant bit.

Plamen Kamenov

Numerade Educator

02:36

Problem 2

Express the following binary numbers as decimal numbers:
(a) $110 ;$ (b) $1100 ;$ (c) $0101 ;$ (d) $11110$ .

Plamen Kamenov

Numerade Educator

00:28

Problem 3

(a) State what is meant by (i) an analogue signal and (ii) a digital signal.
(b) Give one example each of (i) an analogue signal and (ii) a digital signal.

Niamat Khuda

Numerade Educator

00:25

Consider the analogue signal of Figure 1.9.
By sampling (i.e. measuring) the signal every $0.1 \mathrm{ms}$, express the signal as a digital signal. (Assign the nearest integer value to each signal measurement.) It would help to copy and fill in the following table.

Ashley High

Numerade Educator

01:38

Problem 5

The binary code for a signal that is sampled eight times is shown in the table below.
(a) Copy and complete this table.
(b) Put the individual signals together to construct the complete digital signal.
(c) Reconstruct the analogue signal.

Arpit Gupta

Numerade Educator

00:53

Problem 6

Estimate the length of the spiral carrying pits and lands on an ordinary CD of diameter $12 \mathrm{cm} .$ Assume that adjacent parts of the spiral are $1600 \mathrm{nm}$ apart. Explain your method, listing the assumptions you have made.

Hast Aggarwal

Numerade Educator

01:04

Problem 7

It takes 4.0 minutes to record a song on a $\mathrm{CD}$ at a rate of 44100 words per second. A word has a length of 32 bits. How many bytes does the song take?

David Collins

Numerade Educator

00:57

Problem 8

Calculate the storage capacity of an 80 -minute CD that was recorded at a rate of 44100 bits per second using two channels of 16 -bit words each.

Averell Hause

Carnegie Mellon University

01:20

Problem 9

(a) Explain how digital data is stored on a $\mathrm{CD}$.
(b) Explain how interference of light can be used to distinguish a pit from a land.
(c) $\mathrm{A C D}$ player uses a laser of wavelength $680 \mathrm{nm} .$ What is an appropriate pit depth?

Prabhu Ramji

Numerade Educator

02:09

Problem 10

A $12 \mathrm{cm}$ diameter CD lasts for 80 minutes. The laser source of the CD player moves radially outwards as the CD rotates. The initial rate of rotation of the $\mathrm{CD}$ is 500 rpm and the final rate is $250 \mathrm{rpm}$.
(a) Calculate the average speed of the laser source.
(b) Calculate the radius of the innermost track at which the data is stored. Assume that neighbouring spirals are separated by $1600 \mathrm{nm}$.

Bryce Samwel

Numerade Educator

01:42

Problem 11

The laser of a CD player has a wavelength of $740 \mathrm{nm}$ in air. The lands and the pits on the CD are covered by a polycarbonate of index of refraction 1.52.
(a) Calculate the wavelength of the laser in the polycarbonate.
(b) Calculate a suitable pit depth, explaining your reasoning.

Prabhu Ramji

Numerade Educator

01:15