Khao sat vật lý 9

Trờng THCS Phú cát
Họ và tên:
Lớp:
khảo sát đầu năm học 2010 - 2011
Môn: Vật lí 9
Thời gian: 45 phút
I. Khoanh trũn vo ch cỏi trc cõu tr li m em chn:
1. Ampe k dựng :
A. o hiu in th B. o cng dũng in
C. o in tr D. o c cng dũng in v hiu in th
2. t hiu in th 6V vo hai u dõy dn thỡ cng dũng in qua nú l 0,5A. Nu thay bng hiu in
th 24V thỡ cng dũng in qua dõy l :
A. 1A B. 1,5A C. 2A D. 3A
3. t hiu in th 6V vo hai u dõy dn thỡ cng dũng in qua nú l 0,2A. Nu cng dũng in
qua dõy l 0,6A thỡ hiu in th l :
A. 1,2V B. 12V D. 1,8V D. 18V
4. in tr ca mt dõy dn nht nh thỡ :
A. Ch t l thun vi hiu in th gia hai u dõy dn.
B. Ch t l nghch vi cng dũng in qua dõy dn.
C. T l thun vi hiu in th gia hai u dõy dn v t l nghch vi cng dũng in chy qua nú
D. Khụng ph thuc vo hiu in th t vo hai u dõy dn v cng dũng in chy qua nú.
5. t vo hai u in tr R mt hiu in th 3V thỡ cng dũng in qua in tr l 0,6A. R cú giỏ tr
l :
A. 0,5 B. 1,8 C. 5 D. 12
6. Hai in tr R
1
= 2 v R
2
= 4 mc ni tip vo 2 im cú hiu in th 12V. Cng dũng in chy
qua mch l :
A. 1A B. 1,5A C. 2A D. 2,5A

7. R
1
= 2 v R
2
= 4 mc song song vo ngun in cú hiu in th 12V. Cng dũng in qua mch
chớnh l :
A. 9A B. 6A C. 2A D. 3A
8. Chn cõu ỳng nht:
i vi mch in gm cỏc in tr mc song song thỡ :
A. Cng dũng in qua cỏc in tr l nh nhau.
B. Hiu in th hai u mi in tr bng nhau.
C. Hiu in th hai u on mch bng tng hiu in th ca mi in tr
D. in tr tng ng ca on mch bng tng cỏc in tr thnh phn
II. T lun
1. Phỏt biu v vit biu thc nh lut ễm ?
2. Ba in tr R
1
= 20 , R
2
= R
3
= 40 c mc song song vi nhau vo hiu in th 12V
a. V s mch in ca on mch.
b. Tớnh in tr tng ng ca on mch.
c. Tớnh cng dũng in chy qua mch chớnh v qua tng mch r.
d. Nu ly ba in tr ny mc thnh mt mch in thỡ cỏch mc no cho in tr tng ng ln nht.
Tớnh giỏ tr ú.
3. Hai búng ốn khi sỏng bỡnh thng cú in tr l R
1
= 9 v R

2
= 3. Dũng in chy qua hai ốn u cú
cng nh mc l I = 0,8A. Hai ốn ny c mc ni tip vi nhau v vi mt in tr R
3
mc vo
hiu in th U = 12V.
a. Tớnh R
3
hai ốn sỏng bỡnh thng.
b. in tr R
3
c qun bng dõy nicrom cú in tr sut l 1,10.10
-6
.m v chiu di l 1,6m. Tớnh tit din
ca dõy nicrom ny.
im
Li phờ ca thy cụ
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