2014年11月25日 星期二

WS 8.2 answers

II.   Fill in the blanks:
1.     What is an electric current?

Ø   In some materials, there are electrons which are free to move around randomly. These electrons are called (1) free electrons.

Ø   The free electrons in a metal wire move (2) randomly in all directions when there are no dry cells in the circuit.
Ø   The free electrons in a metal wire are ‘driven’ to flow in the (3) same direction when there is a dry cell in the circuit.

2.     Measuring electric current
Ø   An (7) ammeter is an instrument used for measuring the size of an electric current.
Ø   Electric current is measured in (8) ampere(A). Small electric currents are measured in milliamperes (mA).
Ø   We should always connect the (9) positive terminal of the ammeter towards the positive pole of the dry cell and the (10) negative terminal towards the negative pole.

Quiz 6: WS8.1 answers

Fill in the Blanks (9 marks)
1      Dry cell stores chemical(1) energy which can be converted into electrical energy
2      A path for electricity to flow through is called a circuit(1).
3      A circuit which is complete is called a closed circuit(1).          
4      A circuit which is incomplete is called an open circuit(1).
5      Materials that allow electricity to pass through are called electrical conductors(1).
6      Materials that do not allow electricity to pass through are called electrical insulators(1).
7      Metals(1) are electrical conductors while most non-metals(1) are electrical insulators.
8      We use a switch(1) to open or close a circuit.

Challenging Questions (Bonus 3 marks)
1.      List TWO necessary conditions for electricity to flow.
A source of electrical energy(1) and a closed circuit(1)
__________________________________________________________________________________
2.      What non-metal can allow electricity to pass through?
Graphite(1)

__________________________________________________________________________________

2014年11月21日 星期五

真係好堅!

http://hk.on.cc/int/bkn/cnt/news/20141121/bknint-20141121091336607-1121_17011_001.html

俄漢自創「升級版冰桶挑戰」 -195°C液體照頭淋

「冰桶挑戰」早前瘋靡全球,挑戰者以冰水淋頭,為ALS(肌肉萎縮性脊髓側索硬化症)患者籌款。俄羅斯科學家科諾瓦洛夫(Anton Konovalov),近日則自創「升級版冰桶挑戰」,用攝氏零下195度的液態氮氣淋遍全身,惟他事後竟神態自若,身體亦絲毫無損。
科諾瓦洛夫拍下挑戰過程,並上傳到互聯網。片段可見,他先將一片葉子放進冰桶內,再拿出來在手上撕成碎片,以證明桶中的液氮冷得能夠冰封樹葉。他其後將桶子舉起照頭淋,身旁友人更上前戳他的皮膚,證明他身體仍然正常。
科諾瓦洛夫之所以沒有受影響,是有科學根據。根據萊頓弗羅斯現象(Leidenfrost effect),當液體遇到極度炎熱的表面時,表面會形成一層絕緣的蒸氣防護層。因此當液氮淋在科諾瓦洛夫身上時,液態氮只會從皮膚表層掠過,而不會造成傷害。


科諾瓦洛夫用攝氏零下195度的液態氮氣淋遍全身。(互聯網)
科諾瓦洛夫的友人上前戳他的皮膚,證明他身體仍然正常。(互聯網)

2014年11月20日 星期四

濫伐林木,全球暖化愈趨嚴重!

濫伐增加 巴西碳排10年來首升 http://hk.news.yahoo.com/%E6%BF%AB%E4%BC%90%E5%A2%9E%E5%8A%A0-%E5%B7%B4%E8%A5%BF%E7%A2%B3%E6%8E%9210%E5%B9%B4%E4%BE%86%E9%A6%96%E5%8D%87-115002633.html Share via Yahoo新聞 App 下載 Yahoo新聞 Android版 http://goo.gl/WmBs51

Worksheet 8.1 answers

II.   Fill in the blanks:
1.     Conditions for electricity to flow
Ø   Sources of electrical energy:
²  Dry cell stores (1)chemical energy which can be converted into electrical energy;
²  Electrical energy can also be supplied from the power station to the appliance through the socket.
Ø   A path for electricity to flow through is called a (2) circuit.
²  A circuit which is complete is called a (3) closed circuit.
²  A circuit which is incomplete is called an (4) open circuit.

2.         Electrical conductors and insulators
Ø   Materials that allow electricity to pass through are called electrical (5)conductors.
Ø   Materials that do not allow electricity to pass through are called(6) insulators.
Ø   (7)Metals are electrical conductors while most (8)non-metals are electrical insulators.

3.     Switches

We use a (9)  switch to open or close a circuit.  

2014年11月19日 星期三

what is voltage and current

濫開冷氣用電,全球暖化埋身!

港日漸暖化 恐「水淹中環」 http://orientaldaily.on.cc/cnt/news/20141120/00176_046.html

Workbook Integrated Exercise (P.39)

4.        (a)    (i)     B to C, D to E
                (ii)    N to P, R to T
        (b)    The chest volume decreases while the gas pressure inside the chest increases.
        (c)    (i)     The intercostal muscles relax, causing the ribs move downwards and inwards. Hence, the volume inside the chest decreases.
                (ii)    The diagram moves upwards, thus the volume inside the chest decreases.

Workbook Answer 7.6

Section 7.6

A. Multiple choice                                                                                                         p.23-24

E        1.     D
E        2.     D
E        3.     D
E        4.     C

B. Fill in the blanks                                                                                                              p.25

E     (a)    contract
(b)    upwards
(c)    outwards
(d)   downwards
(e)    increases
(f)    decreases
(g)    relax
(h)    inwards
(i)     downwards
(j)     upwards
(k)    decreases
(l)     increases

C. Matching                                                                                                                         p.25

E     (a)    v
(b)    i
(c)    ii
(d)   vi
(e)    iii
        (f)    iv

2014年11月15日 星期六

Long Q3-2

c. 以下實驗顯示光合作用的某些條件. 位置P和S是綠色的, Q和R是非綠色部分. 位置R和S被鍚紙覆蓋.
i. 測試澱粉後, 位置P, Q, R和S的顏色如何?
ii. 位置Q在實驗完結時不含有澱粉, 為什麼?
iii. 位置R在實驗完結時不含有澱粉, 為什麼?
iv. 從實驗可以得出什麼結論?

1st term test long Q1


題解:
當自發粉(baking powder)與水混合後會釋出Gas X, 此氣體由hydrogencarbonate indicator測試, 而顏色由紅色轉為黃色.

a. 提出氣體X是什麼?
b. 如果氣體收集並倒在蠟燭的火焰上, 會發生何事? 解釋你的答案.
c. 如果自發粉加在有水生植物的水盤內, 這會如何影響光合作用的速率? 解釋你的答案.

Long Q3-1

3. 下圖顯示測試一塊綠葉的過程.
a. 利用A-F 正確排列上圖的次序.
b. 解釋A, B, D和E步驟的目的.

1st term test Long Q2


a. 在以上的實驗, 花生屬於火三角的什麼部分?
b. 舉出花生在以上實驗的能量轉變.
c. 以上實驗有一個過程發生, 當中花生儲存的能量會釋出.
i. 這個過程的名稱是什麼?
ii. 寫出一個文字方程式, 以顯示發生於花生的改變.
d. 利用以上裝置, 比較5g花生和5g餅乾的能量值, 列出3個要維持不變的變項(variable)

2014年11月12日 星期三

2014年11月9日 星期日

點解會不適?請解釋!

華人行8支滅火用CO2洩漏 兩女1昏迷1胸痛送院 http://hk.on.cc/hk/bkn/cnt/news/20141109/bkn-20141109154949419-1109_00822_001.html

2014年11月7日 星期五

亂打胰島素 隨時血糖低 http://orientaldaily.on.cc/cnt/news/20141108/00176_075.html

2014年11月3日 星期一

Workbook Quick Review (P.42-44)

A
(a)    Fuel
(b)    Temperature
(c)    Oxygen
(d)   goes out

B
(a)    (i)     light energy
        (ii)    chlorophyll
  (iii)     water
(b)    (i)     carbon dioxide
        (ii)    oxygen
  (iii)     oxygen
        (iv)   carbon dioxide

C
   (a)    (i)     Air
         (ii)    lungs
   (b)    (i)     Oxygen
   (ii)    carbon dioxide
(c)    (i)     Chemical
  (ii)    oxygen
        (iii)   carbon dioxide
(d)   (i)     less
        (ii)    more
  (iii)   less
  (iv)   more
  (v)    lower
  (vi)   higher
(e)    (i)     glowing splint
        (ii)    colourless
        (iii)   milky
        (iv)   red
        (v)    yellow
        (vi)   blue
        (vii)  pink

D
(a)    photosynthesis
(b)    oxygen
(c)    respiration
(d)   carbon dioxide

Workbook Integrated Exercise (P.30-39) answers

Workbook Integrated Exercise (P.30-37) answers

A
1.     True
2.     True
3.     False
4.     True
5.     True
E6.     False
E7.     True
8.     False

B
1.     C
2.     C
3.     D
4.     D
5.     D
6.     A
E7.     C
8.     D

C
1.     (a)    ii, iii, v, vii
   (b)    i, iv, vi, viii
2.     (a)    iii, iv
   (b)    ii, v
           (c)    i, vi

D. Questions  p.36-41

1.     (a)    (i)     oxygen
(ii)    Put a glowing splint into the test tube. If it relights, it shows that the gas is oxygen.
(iii)   It is used to provide carbon dioxide for the water plant to carry out photosynthesis.
        (b)    (i)     The rate of bubbling increase.
                (ii)    The rate of photosynthesis increases when the light intensity increases.

2.     (a)    (i)     It remains colourless. It shows that no carbon dioxide is present in the air entering the bell jar.
(ii)    It changes from red to yellow. It shows that the mouse releases carbon dioxide.
(b)    Sodium hydroxide solution absorbs carbon dioxide from the incoming air. This ensures that the colour change of the indicator in flask C is due to carbon dioxide released from the mouse.
        (c)    (i)     Place the set-up in the dark. (or other reasonable answers)
(ii)    Without light, the plant cannot undergo photosynthesis. This ensures that the experimental result is due to respiration of the plant only. (or other reasonable answer)

3.     (a)    (i)     Respiration: food + oxygen ----=>   carbon dioxide + water energy
                (ii)                                                                    light energy
                        Photosynthesis: carbon dioxide +water --------------=>  food +oxygen
                                                                                        chlorophyll
        (b)    (i)     The rate of net oxygen absorption will be negative.
                (ii)    The rate of net oxygen absorption will be positive.
        (c)    (i)     From 0600 to 1800
                (ii)    From 1800 to 2400 and 0000 to 0600

E4.     (a)    (i)     B to C, D to E
                (ii)    N to P, R to T
        (b)    The chest volume decreases while the gas pressure inside the chest increases.
        (c)    (i)     The intercostal muscles relax, causing the ribs move downwards and inwards. Hence, the volume inside the chest decreases.

                (ii)    The diagram moves upwards, thus the volume inside the chest decreases.



















Workbook Answers 7.5

A
1.     B
2.     C
3.     C
4.     D
5.     C

B
(a)
Tube
Does respiration take place?
(ü / û)
Does photosynthesis take place?
(ü / û)
Colour of the indicator
The level of carbon dioxide (unchanged / increase / decrease)
A
ü
ü
red
unchanged
B
ü
ü
purple
decrease
C
û
û
red
unchanged
D
ü
û
yellow
increase
E
ü
û
yellow
increase
F
ü
û
yellow
increase
G
û
û
red
unchanged
H
ü
û
yellow
increase
(b)    In the dark, the plant does not undergo photosynthesis. However, both the plant and snail carry out respiration which gives out carbon dioxide. Therefore, the level of carbon dioxide increases and the indicator changes from red to yellow.

(c)    Under bright light, there is a net intake of carbon dioxide in plants. In the dark, there is a net release of carbon dioxide in plants.