4 Piv Txwv ntawm Cov Lus Nug Txog Lub Suab
1. Cov ntsiab lus A thiab B yog 4 m thiab 9 m ntawm qhov chaw suab, raws li. Yog tias I A thiab I B yog qhov muaj zog ntawm cov ntsiab lus A thiab B, raws li , ces I A : I B yog…
A. 3: 2
B. 4: 9
C. 9: 4
D. 16: 81
E. 81: 16
Kev Sib Tham
Nws paub tias:
Qhov deb ntawm qhov chaw A ntawm qhov chaw suab (r A ) = 4 meters
Qhov deb ntawm qhov chaw B ntawm qhov chaw suab (r B ) = 9 meters
Lub suab nrov ntawm qhov chaw A = I A
Lub suab nrov ntawm qhov chaw B = I B
Nug: Kuv A : Kuv B
Lus teb:
Cov mis rau kev sib raug zoo ntawm qhov muaj zog thiab qhov deb:
Cov lus teb yog yog E.
2. Lub suab nrov ntawm lub tshuab xaws thaum nws ua haujlwm yog 10-9 Wm-2Rau qhov muaj zog ntawm lub suab ntawm 10-12 Wm-2, ces lub suab nrov ntawm 10 lub tshuab xaws zoo sib xws uas ua haujlwm yog…..
A. 400 dB
B. 300 dB
C. 40 dB
D. 30 dB
E. 20 dB
Kev Sib Tham
Nws paub tias:
Kuv = 10 -9 W/ m2
Io = 10 -12 W / m2
x = 10 os
Nug: TI 10 tshuab xaws?
Lus teb:
TI 10 lub tshuab = TI 1 lub tshuab + 10 cav x
TI = 30 + 10 log 10
TI = 30 + 10 log 10 1
TI = 30 + (1)(10)(log 10)
TI = 30 + 10
TI = 40 dB
Cov lus teb yog C.
3. Lub zog nrov ntawm ib tug muv yog 10 dB. Yog tias lub suab nrov ntawm txhua tus muv suav tias zoo ib yam thiab qhov kev hnov lus ntawm tib neeg yog 10 −12 Wm −2 , ces lub zog nrov ntawm 1000 tus muv yog ...
A. 10 −8 Wm −2
B. 10 −7 Wm −2
C. 10 −6 Wm −2
D. 10 −5 Wm −2
E. 10 −4 Wm −2
Kev Sib Tham
Nws paub tias:
TI = 10 dB
Io = 10 -12 W / m2
x = 1000 os
Nug: TI 1000 muv?
Lus teb:
4. Lub suab ntawm lub tsheb kauj vab thaum lub suab nrov yuav muaj zog txog 40 dB, thaum lub suab ntawm lub tsheb kauj vab thaum lub suab nrov yuav muaj zog txog 60 dB (Io = 10 -12 W m -2 ). Yog tias 100 lub tsheb kauj vab thiab 10 lub tsheb kauj vab raug tshuab tib lub sijhawm, ces qhov sib piv ntawm cov suab nrov ntawm cov tsheb kauj vab rau cov tsheb yog ....
A. 5: 6
B. 6: 7
C. 7: 8
D. 8: 9
E. 9: 10
Kev Sib Tham
Nws paub tias:
Qib zog (TI) ntawm lub suab tsheb kauj vab = 40 dB
Lub zog ntawm lub tsheb lub suab nrov (TI) = 60 dB
Qhov tsawg kawg nkaus uas tib neeg hnov tau (Io ) nruab nrab = 10 -12 W m -2
Lo lus nug: TI piv ntawm 100 lub maus taus rau TI ntawm 10 lub tsheb yog dab tsi?
Lus teb:
Qhov kev sib piv ntawm TI 100 maus taus nrog TI 10 lub tsheb yog:
60: 70
6: 7
Cov lus teb yog B.
Qhov chaw nug lus:
Cov Lus Nug Txog Kev Xeem Physics Hauv Tebchaws Rau Tsev Kawm Ntawv Theem Siab/Tsev Kawm Ntawv Theem Siab Ua Haujlwm
