phy~從不知怎麼是對的

小霞的fans · 發表於 16/4/2010 01:47 PM

本帖最後由小霞的fans 於 15/4/2010 06:50 PM 編輯

30# 囧囧中自有囧囧

potential difference係唔係姐係2點之間voltage既difference呀??

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我想問X同Y之間既potential difference係幾多??

sy · 發表於 16/4/2010 02:35 PM

30# 囧囧中自有囧囧

potential difference係唔係姐係2點之間voltage既difference呀??

我想問X同Y既potential difference係幾多??
小霞的fans 發表於 16/4/2010 01:47 PM

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potential difference=voltage

renz · 發表於 18/4/2010 01:21 PM

4. 1997/I/4

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A student uses the apparatus shown in Figure 5 to perform an experiment to measure the specific latent heat
of fusion of ice. He uses a joulemeter to measure the energy required to melt a certain amount of ice.
(a) Draw a diagram to show how the apparatus can be set up for the experiment. (3 marks)
(b) The following data are obtained in the experiment :
Initial joulemeter reading = 28 000 J
Final joulemeter reading = 40 400 J
Mass of water collected in the beaker = 0.045 kg.
Calculate the specific latent heat of fusion of ice. (3 marks)
(c) Why should the ice used in the experiment be crushed ? (2 marks)
(d) A teacher comments that the result of this' experiment is not accurate. She points out that a control
experiment is required in order to improve the accuracy of the experiment.
*(i) Describe how the control experiment can be set up and explain its function. (5 marks)
(ii) After setting up the control experiment, the student repeats the above experiment. Would you
expect the specific latent heat of fusion obtained to be higher or lower than that obtained in (b)?
Explain your answer. (2 marks)

同埋mc兩題

18. 2000/II/21

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The above apparatus is used to find the specific latent heat of vaporization of water lv. Which of the following
factors will cause the result obtained to be larger than the true value of lv?
(1) Some energy is lost to the surrounding
(2) Some steam condenses and drips back into the beaker
(3) Some boiling water inside the beaker splashes out of the beaker
A. (1) only B. (3) only C. (1) and (2) only D. (2) and (3) only E. (1),(2) and (3)

20. 2002/II/21

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The result obtained in Q.19 is found to be higher than the true value of the specific heat capacity of the
metal. Which of the following is a probable reason?
A. Some hot water is still adhered to the metal block when the block is transferred to cold water.(19)
B. Some energy is lost to the surroundings when the metal block is transferred to cold water.
C. Some energy is absorbed by the cup.
D. The temperature of the metal block is still higher than 38ºC when the final temperature of the water
in the cup is measured.

囧囧中自有囧囧 · 發表於 18/4/2010 06:06 PM

本帖最後由囧囧中自有囧囧於 18/4/2010 06:13 PM 編輯

02 18 同09 第12題一樣-_,-
heat loss to surronding
energy 大左 E=ml
change of mass 不變 l大左
(2) more energy is required to boil to same amount of water
e大左 change of mass不變 l大左
(3) change of mass大左 e不變ge話 l細左
edited
02 20 mm=mass of metal mw
有水係上面多左一樣野比energy*
之後點自己諗=P

pokedigi · 發表於 24/4/2010 12:01 PM

本帖最後由 pokedigi 於 24/4/2010 12:15 PM 編輯

30# 囧囧中自有囧囧

potential difference係唔係姐係2點之間voltage既difference呀??

登錄/註冊後可看大圖

我想問X同Y之間既potential difference係幾多??
小霞的fans 發表於 16/4/2010 01:47 PM

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正確的講voltage只是potential 的單位
so 問p.d.(potential difference)姐是問2點(wire上)的potential差幾多voltage
答案是以V做單位
如果wire 2點之間冇其他野,而resistance of wire=0的話,p.d.就是0(V=IR,R=0)
(ce是比較少出現potential 呢個字,但到al 就會是咁講)
一般而言,一個circuit中,battery的emf
(emf 姐是battery 2邊的p.d.,ce有時都會出現)
是等於任何一條route中所有across其他物件的p.d.的總和
除非條題目有講 internal resistance (battery 自己的 resistance)
不過應該是al 先會問
呢條題目得一條route,一個物件,所以佢的p.d.就=emf=6V

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[求助] phy~從不知怎麼是對的