Đề song ngữ Vật lí 9 - Phạm Văn Minh (Có đáp án + Ma trận)

 Đề 4
Question 1. An electric stove is connected to a constant voltage. How does heat radiate in a second if 
the truncated wire length is cut short?
A. double. B. halves. C. quadruple. D. does not change.
Question 2. Two resistors R1 = 15Ω with maximum current resistance of 2A and R2 = 10Ω with a 
maximum current of 1A. Maximum voltage potential can be placed on the two terminals of parallel R1 
and R2 in parallel:A. 40V B. 10V C. 30V D. 25V
Question 3. In the flashlight used for decoration is a flashing light bulb automatically. The flashing of 
this bulb led to the blinking of the entire bulb. Ask where the flashing light bulb automatically caught 
where the effect of it is best?
A. Top of the range. B. Between ranges. C. End of sequence. D. The same is good everywhere.
In a circuit consisting of three equal resistors R in series, the current through the circuit is 2A. With a 
constant voltage, if one resistor is removed, the current is:A. 1A B. 1.5A C. 3A D. 2A
Question 5. The two resistors R1, R2 are connected in series, placed on the first two circuits of voltage 
U, the voltage at the two ends of the resistors are U1, U2. Please indicate which of the following is true? 
Question 6. A segment conductor is homogeneous. Place a fixed voltage at the ends of the wire, the 
current through the wire is I1. Double the wire and then connect the two ends of the folded wire with 
the above voltage, then how much current through the wire is I2?
Question 7. For three resistors R1 = 4, R2 = 6, R3 = 12 parallel rods. Equivalent resistance R of the 
circuit is valid: A. 6 12 D. 4 <R <6
Question 8. Cut a conductor of homogeneous sections are made in two sections, the first section is four 
times longer. Compare the current flowing through the wires, if at the two ends of each wiring an equal 
voltage? A. I2 = 4I1 B. I2 = 3I1 C.I2 = 2I1 D.I2 = I1
Question 9. Which of the following light bulbs, which ball light the strongest?
A. 220V - 75W B. 220V - 40W C. 110V - 150W D. 110V - 100W
Question 10. What statement is true when it comes to the magnetic susceptibility of steel:
a. When magnetized, steel retains its magnetic strength much weaker than iron.
b. With the same condition, the magnetic steel is weaker than copper.
c. Place the steel core in the magnetic field, the steel core is infected from.
d. The sentences a, b, c are true.
Question 11. An electric kettle has two resistors R1 and R2. If R1 and R2 are connected in series, the 
boiling time for warm water is 50 minutes. If R1 and R2 are parallel, the boiling time of the kettle is 12 
minutes. Ignoring the heat loss with the environment and boiling conditions is the same, ask if each 
individual resistor, then the corresponding time boil water? Let the voltage U be constant. Answer:
 Question 1 2 3 4 5 6 7 8 9 10
 Answers A B C D C D B A D C
Question 11:
Change t1 = 50 minutes; t2 = 12 minutes into PT (*)
R1 = 30. and R2 = 20.
• We have t3 = = 30 minutes and t4 = = 20 minutes.
• So, if using individual resistors, the time to boil water in the kettle is 30 and 20 ph.
corresponding to when using R1, R2 serial; R1, R2 in parallel; just use R1 and only use R2, according 
to Juniper's law we have:
 2 2 2 2 2
 U .t U .t1 U .t2 U .t3 U .t4
 Q (first)
 R R1 R2 R1.R2 R1 R2
 R1 R2
 • We calculate R1 and R2 according to Q; U; t1 and t2:
 2
 U .t1
 + From (1) R1 + R2 = 
 Q
 •
 2 4
 U .t2 U .t1.t2
 Also from (1) R1 . R2 = .(R R ) 
 Q 1 2 Q 2
According to Vi-et theorem, R1 and R2 must be the solution of the equation: 
 U 2 .t U 4.t .t
R2 - 1 .R + 1 2 = 0(*) 
 Q Q2
Change t1 = 50 minutes; t2 = 12 minutes into PT (*)
R1 = 30. and R2 = 20.
• We have t3 = = 30 minutes and t4 = = 20 minutes.
• So, if using individual resistors, the time to boil water in the kettle is 30 and 20 ph.
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 Người ra đề: Phạm Văn Minh
 Đơn vị: Trường THCS Hùng Thắng