1969-07-24 — Page 23

2.5JUL:769

育教僑華頁三第張六第日一十月六年個己瑟夏

WAH KIU YAT PO 報日僑

GITY HALL

四期星,日四廿月七年九六九一麼公年八十五國民華中

中學同學學科 生活知識進修

摺合偶極子

堅道文書院編

應用科學

育敎僑華

導波器

小學畢業同學

暑期進修專欄

續第一講電視機

(3)备形的傳真度擴音机的傳喜度是指 对整音域放大的真实程度,尤其是高频 和低頫方面,因為这两方面較難,有良好的 放大,而電視机的傳真度,亦有相類似的 意思,是指对备形的顯像能,不但要纖 毫畢現,而且粗调的地方也要界限分明,也 就是說,对高損和低頻都要有良好的表現 能力。試看下面,

TOH

仅射器引线

天线的好壞,决定於其坛益和方向性 坛益愈強,方向性愈強,便是較好的天

线。天线和電視机间的联繫,少不了一條 31入线,而这些引入线是有一定的規格 不良的引入线是会對訊号生極大的衰 诚和反射,現試将常用的引入线下

智慧出版社主編

英文數學

LESSON-FOUR

DIVISION

means, "divide"

EXAMPLE 1.

Divide 2864.by 4,

SOLUTION:

ANSWER:

種類 形状 型號縂阻抗品

每100公尺

EXAMPLE 2

在这大圓的中央;有何仓四方的黑白线 構成的楔形束,楔形束的旁边,註有200.. 300,400,500,600等字樣这些数字,是指在数 字旁里白线的调度,為全备面调度所佔的 份数数字。假如有某机能明顯的分 辨到標示400的位置,则这机所能顯示、 最幼的线條是有全面面洞度400份之一

阔的线条,这间数字,也可從下面简单的 計算方法算出其所代表的懶率

現先假設这机是625线和每秒变换 25次畫面,則垂直掃描的頻率為每秒 50次(间隔棉描便频率加倍)

水手掃描頻率=50x625-

15625

B. | "400" PIT (X&0THB = = 156251460

-6.35 mys 这就是说,这机的解像力高频方面已 達6.255.

再看,圓内頂部和底部,各有粗线 西條,这是用来测验对低頻的解像力 魂频放大级需要对这低頻有不失真的 放大,才能在形上顯示清楚明朗的里 线,否則其界限會模糊、不清或全线的 深浅程度不同,

(六)天线安装和故障修理的技術成誤

現時普遍用的電視天线都是由三部 份構成,是為導波器(Director)仅射器 (Reflector)和天线本部試以八木型天线 為例其導波器有多條適当長度的金属 短棒反射器則由一條或多條的金属短 棒構,亦有造成弧形的细状,天线本 9 9 1 13 122 = <il for } (Folded Dipole) 将此三者以適当的距离固定於橫桿上 即成如下面所示

(Coaxial Cable) (Coxixial Couble) (Botane fine)

同軸電實

同軸電雄

辛衡型 平衡型

HO

10C-2V 75-2 16.00B

7C-2V 752 19.5dB

"5C-2V| 75n 240JB

3C-2V 752 32.0dB.

8D-2V 50~

190dB 5D-2V 50~ 23.0dB

3D-2V 50-2 350dB M-200-25 240-2- 160dB

The required quotient

# 2864 ÷ 4 = 716.

The required quotient is 716.

If 707,707 is the dividend, and 101 is the divisor what is the quotient?

Note:

Dividend = Divisor x Quotient + Remainder

SOLUTION

ANSHER=

EXAMPLE 3

The required quotient

Dividend Divisor

➡ 707,707 # 101 – 7,007

The required quotient is 7,007-

If the product of three numbers is 40,800, the first number is 40 and the second is 60" What is the third, number7

SOLUTION:

The third number = 4080040 60

$ 17

The third number is 17,

ANSWER:

M-200-3 300m

EXAMPLE

160dB

M-300-1 300 10dB

M-300-2 300~ 95dB

天线的坛益是以dB為標準,而引入线 的衰减也是以dB計算,故說到這裡,不得 不光对dB的意義作一间暑的解释

-10 dB / +5 2-10 Bell (dB / deci- Bell的简称),而Bell的定義是两间電 功率比例的对数值,故此

dB = 10.109/

Find by division how many times 6 gallons 4 pints can be taken from 65 gallons? SOLUTION

ANSWERS

EXAMPLE

The required number of times =*65 gall, ÷ 6 gall. 4 pinta = 520 pints ÷ 52 pints = 10

The required number of tines is 10.

Find the quotient when 3 sq. yd. 1 sq. ft. 24 is divided by 26.

SOLUTION TO

·ANSWER #

EXAMPLE. 6

The required quotient.

= 3 sq. yd. 1 sq. ft. 24 sq. in. → 26

1 sq. ft. 12 sq. in.

The required quotient is 1 sq. It. 12 sq. in.

If 352 sweets are shared among a number of boys, and if each boy gets 16 sweets, how many boys are there?

SOLUTION: The required number of boya

ANSWER

352 16 22

The required number of boys is

假如此電功率两端的阻抗相子,则

EXERCISE 4

P = E2/R

P2 = Ez / R1

R1 = R

dB = 10 log!

(1) Divide: eight thqusand five hundred

and fifty-six by four, (2) A boy is given some sums to do, If

he does 6 every minute, how many minutes. will he take to do one hundred and twenty-six?

(1):

(2).

= 20log

(3) How many 28 lb.-bag of flour can

be made out of a loory containing half a.ton?

(3)

baga

(4) A clock ticks twice every second,

Hok. many times does it tick in a quarter of an hour?.

(4)

(5) is the quotient if the dividend:

is 6,516 and the divisor is 187 (6) The product of four numbers is

(5)

12,960. If the first one is 4, the second is 18 and the third ús 12, What is the fourth" one?

(6)

故此,由d好的数值不但可推算其電功 的比值,更可计算其宽压的比值,

現在再回說天线:其坛益的dB数值 是以極偶子(dipole)為基準,例如說,某关 傳的红益是6奶则

Anti log 0.3

这就說,这根天线所接收的訊ㄓㄨㄥ 電 压比極偶子接收的大一倍 同樣方法也可計算运,假如某引入线 每百公尺的衰減為20dB則經一百公尺 的3引入线後,其訊是電压会口是原来的 千份之一。

{7) 1 gallon 2 pints of milis cost $6.00.

How much would. 1. pint cost? -

A number is divided by 3. If the quotient is 26 and the remainder 1. what is the number?

(8)

(9) The total weight of rice is 2 tons

10 cwt. If each bag contains 1 cut. 28 lb. of rice, how many bags are there?

(10) Divide 24 gallons 7 pints by 9.

(a) What is the quotient?.

(b) What is the remainder?

(10a)zugall. (10b).

(11) The total weight of 'cargoes 1s

7 tons 40 lb. If each bag containg 1 cut.19 16., how many bags are there?

(11). (12) The total weight of rice 1s' 22 picule.

68 catties. If each basket contains 63 catties, how.many baskets are theref

(12) baakati