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TRƯỜNG THCS TÂN BÌNH ĐỀ CƯƠNG ÔN TẬP HKII Họ tên: f2.hcm.edu.vn/data/hcmedu/thcstanbinh/2018_3/de_cuong_ly_7_hkii_17-18... · PDF fileElectron có thể dịch chuyển

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  • Trang 1

    PHN I: L THUYT

    Cu 1: C th lm vt b nhim in bng cch no? Vt b nhim in c kh nng g?

    C th lm vt b nhim in bng cch c xt.

    Cc vt nhim in (vt mang in tch) c kh nng ht cc vt nh khc.

    Cu 2: K tn v nu k hiu ca cc loi in tch hc. in tch ca thanh thy tinh khi

    c xt vo la, in tch ca thanh nha sm mu khi c xt vo vi kh c qui c nh

    th no?

    C hai loi in tch: in tch dng (+), in tch m ().

    Qui c:

    in tch thanh thy tinh khi c xt vo la l in tch dng (+).

    in tch thanh nha sm mu khi c xt vo vi kh l in tch m ().

    Cu 3: Khi no cc vt nhim in y nhau? Khi no cc vt nhim in ht nhau? Khi no

    mt vt s nhim in dng? Khi no mt vt s nhim in m?

    Cc vt nhim in cng loi th y nhau.

    Cc vt nhim in khc loi th ht nhau.

    Mt vt nhim in dng khi mt bt electron.

    Mt vt nhim in m khi nhn thm electron.

    Cu 4: Trnh by s lc v cu to ca nguyn t.

    Nguyn t gm ht nhn gia mang in tch dng, cc electron chuyn ng xung quanh ht nhn to thnh v nguyn t mang in tch m.

    Bnh thng nguyn t trung ha v in (ngha l: tng in tch dng ca ht nhn bng tng in tch m ca cc electron).

    Electron c th dch chuyn t nguyn t ny sang nguyn t khc, t vt ny sang vt khc.

    Cu 5: Ngun in dng lm g? Cho v d mt s ngun in trong i sng. Mi ngun

    in u c chung c im l g? iu kin c dng in chy trong mch in l g?

    Ngun in dng cung cp dng in cho cc thit b in hot ng. (VD: pin, acquy, cm in, my pht in,...)

    c im ca mi ngun in l c u c hai cc: cc dng (+) v cc m ().

    iu kin c dng in chy trong mch in: dng in ch chy trong mch kn bao gm cc thit b in c ni lin vi hai cc ca ngun in bng dy in.

    TRNG THCS TN BNH CNG N TP HKII

    MN: VT L 7

    NM HC: 2017 - 2018 H tn:

    Lp: 7/

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    Cu 6: Dng in l g? Dng in trong kim loi l g?

    Dng in: l dng cc in tch dch chuyn c hng.

    Dng in trong kim loi: l dng cc electron t do dch chuyn c hng.

    Cu 7: Th no l cht dn in, cht cch in? Cho v d vi mi loi.

    Cht dn in: l cht cho dng in i qua. (VD: bc, ng, ch, st, nc thng dng,)

    Cht cch in: l cht khng cho dng in i qua. (VD: s, nha, g, nc nguyn cht,)

    Cu 8: S mch in l g? S mch in c cng dng g? Nu qui c v chiu dng

    in trong mch in.

    S mch in: l hnh v biu din mch in bng k hiu ca cc b phn mch in.

    Cng dng ca s mch in: mch in c m t bng s v t s mch in c th lp thnh mch in tng ng.

    Qui c chiu dng in: chiu dng in l chiu t cc dng qua dy dn v cc thit b in ti cc m ca ngun in.

    (Lu : Chiu dng in theo qui c ngc li so vi chiu dch chuyn ca cc electron t do

    trong kim loi.)

    Cu 9: Trnh by v cc tc dng ca dng in. Mi tc dng ca dng in nu mt s ng

    dng trong thc t.

    Tc dng nhit: dng in i qua mi vt dn thng thng u lm cho vt dn b nng ln, nu vt dn nng ln ti nhit cao th pht sng.

    (ng dng trong: Bn i, my sy tc, ni cm in, m in, bng n dy tc,...)

    Tc dng pht sng: dng in c th lm pht sng bng n bt th in v n it pht quang (n Led), mc d cc n ny cha nng ti nhit cao.

    (ng dng trong: bng n bt th in, n it pht quang (n Led), n bo ca tivi,...)

    Tc dng t: dng in c tc dng t v n c th lm quay kim nam chm v ht cc vt bng st, thp.

    (ng dng trong: nam chm in, chung in, cn cu dng nam chm in,...)

    Tc dng ha hc: dng in c tc dng ha hc, chng hn khi cho dng in chy qua dung dch mui ng th n tch ng ra khi dung dch, to thnh lp ng bm trn thi than

    ni vi cc m ca ngun in.

    (ng dng trong: k thut xi (m) in cho kim loi, n trang...)

    Tc dng sinh l: dng in c tc dng sinh l khi i qua c th ngi v ng vt, gy ra mt s biu hin nh: c co git, tim ngng p, t lit thn kinh,

    (ng dng trong: chm cu in, my kch in tim, cc loi my massage vt l tr liu,...)

    Cu 10: Cng dng in cho bit iu g? Nu k hiu v n v ca cng dng in.

    Cng dng in: cho bit mc mnh, yu ca dng in.

    K hiu ca cng dng in l: I

    n v ca cng dng in l: ampe (A), miliampe (mA).

    1 A = 1000 mA ( mAA x 1000 ) ; 1 mA = 0,001 A ( AmA 1000: )

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    Cu 11: Hiu in th c to ra u? Nu k hiu v n v ca hiu in th.

    Hiu in th: c to ra gia hai cc ca ngun in.

    K hiu ca hiu in th l: U

    n v ca hiu in th l: kilvn (kV), vn (V), milivn (mV).

    1 kV = 1000 V ( VkV x 1000 ) ; 1 V = 0,001 kV ( kVV 1000: )

    1 V = 1000 mV ( mVV x 1000 ) ; 1 mV = 0,001 V ( VmV 1000: )

    Cu 12: Mun o cng dng in, o hiu in th phi dng dng c g? Nu cch mc

    cc dng c vo trong mch in.

    Dng c dng o cng dng in: l ampe k.

    Cch mc ampe k vo mch in: mc ampe k ni tip vi vt cn o cng

    dng in, sao cho cht (+) ca ampe k ni

    vi cc (+) ca ngun in

    Dng c dng o hiu in th: l vn k.

    Cch mc vn k vo mch in: mc vn k song song vi vt cn o hiu in th,

    sao cho cht (+) ca vn k ni vi cc (+)

    ca ngun in.

    Cu 13: S vn ghi trn mi ngun in cho bit iu g? S vn ghi trn mi dng c in

    cho bit iu g?

    S vn ghi trn mi ngun in: cho bit gi tr hiu in th gia hai cc ca ngun in khi cha mc vo mch.

    (V d: Trn v mt acquy c ghi 12 V, s cho bit hiu in th gia hai cc ca acquy khi

    cha mc vo mch l 12 V)

    S vn ghi trn mi dng c in: cho bit hiu in th nh mc dng c hot ng bnh thng.

    (V d: Trn mt bng n c ghi 220 V, s cho bit hiu in th nh mc bng n

    hot ng bnh thng l 220 V)

    Cu 14: on mch mc ni tip c nhng c im g?

    Trong on mch mc ni tip:

    Cng dng in c gi tr bng nhau ti cc v tr khc

    nhau ca on mch: I = I1 = I2

    Hiu in th gia hai u on mch bng tng cc hiu

    in th thnh phn: U = U1 + U2

  • Trang 4

    PHN II: BI TP.

    Bi 1: Bn di cc xe ch xng (du), ngi ta

    thng treo mt si dy xch bng st ni thng

    xe c cha xng (du) vi mt ng (phn khoanh

    trn trong hnh 1). Theo em, ti sao cn phi lm

    nh vy?

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    Hnh 1

    Bi 2: (HKII 08 - 09) Ht nhn trong mt nguyn t canxi c in tch l +20e. V nguyn t

    canxi ny c tng in tch l 18e. Nguyn t ny tr thnh ht mang in tch g? V sao?

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    Bi 3: Hnh 2 l s cu to n gin ca mt nguyn t.

    Hy cho bit:

    a/. Nguyn t ny c bao nhiu in tch dng, in tch m?

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    b/. Trong nguyn t, ht mang in tch dng c tn gi l g? Ht mang in tch m c tn gi l g?

    ...................................................................................................

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    Hnh 2

    Bi 4: C xt thanh nha sm mu vo mnh vi kh. Hi:

    a/. Theo qui c, thanh nha sm mu s b nhim in loi g? Lc ny, thanh nha nhn thm hay mt bt i electron?

    b/. Mnh vi kh nhn thm hay mt bt i electron? Lc ny, mnh vi kh s b nhim in loi g?

    c/. Electron di chuyn t vt no sang vt no? Thanh nha sm mu v mnh vi kh sau khi c xt nu a li gn nhau th s ht hay y nhau?

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  • Trang 5

    Bi 5: (HKII 10 - 11) Thanh thu tinh sau khi c xt vi la a li gn vt A, th thy thanh thy

    tinh b vt A y ra xa. Hi vt A ang nhim in loi g? V sao?

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