Đề song ngữ Vật lí 9 - Đề 3+4 - Phạm Văn Minh (Có đáp án)

 Đề 3
EX 1 : The cylinder hex made with a same material, with same length, appear to S1, S2, matching the 
 2 2
 R1 S1 R1 S 2 R1 S1 R1 S 2
terms of terms of interest:A. = . B. = . C. 2 . D. 2 .
 R2 S 2 R2 S1 R2 S 2 R2 S1
EX 2When applying a 12V voltage to both ends of a coil, the current through it is 1.5A. The length of 
the wire used to wrap this coil is (Knowing that this type of wire if 6m long has a resistance of 2)
 A.l = 24m B. l = 18m . C. l = 12m . D. l = 8m .
EX 3: The two wires are made of copper with the same cross-section S. The first wire has a length 
of 20cm and a resistance of 5. The second wire has a resistance of 8. The second wire has the 
length: A. 32cm . B.12,5cm . C. 2cm . D. 23 cm .
EX 4: Two conductors are made of the same material having the same cross section, with lengths l1, 
l2. Their respective resistances satisfy the following conditions:
 A R1/R2 = l1/l2 B. =. R1/R2 = l2/l1 C. R1 .R2 =l1 .l2 . D. R1 .l1 = R2 .l2 .
EX 5 : Rope is a component:
A. Used to change the conductor material in the circuit.B. Used to adjust the current in the circuit.
C. Used to adjust the voltage between two terminals.D. Used to change the wiring separately in the circuit.
EX 6 : In the winding, the alternating current becomes constant when the magnetic field lines through 
the S section of the coil
 A. Increasing that switch to reduce. B. is decreasing that switch to increase.
 C. Increase regularly and decrease regularly. D. Rotate up and down
EX 7 The induction current in the coil windings is reversed when the magnetic field lines pass through 
the S section of the coil A. increase over time. B. decrease over time. C. increase or decrease steadily 
over time. D is increasing but turning to decrease or vice versa.
EX. 8 Electromagnet used in equipment:
A. Generator. B. Make compasses. C. Electromagnetic relays. D. electric iron.
EX 9: Electric speakers based on:
A. The effect of the magnetic field on the wire frame is through the current.
B. magnetic effect of the magnet on the conductor with current flowing through.
C. effect of current on straight wire with current flowing through.
D. magnetic effect of magnetic field on straight wire with current flowing through.
EX 10: Left Hand Rules are used to identify:
A. The direction of the electromagnetic force. B. The direction of the magnetic field
C. The direction of current flowing through the wire. D. The direction of the magnetic poles.
 II. ESSAY
EX An electric cooker consisting of two resistors R1 and R2. With the same voltage and the same 
kettle, if the resistor R1 is boiling water after t1 = 30 minutes, if R2 is used, the water is boiling after t2 = 
20 minutes. Resistors change insignificantly according to temperature, the heat generated by the 
environment is proportional to the power supplied to the kitchen. Ask how long the warm water will 
boil if using both resistors in the following two cases:
a. Two resistors connected in series.
b /. Two resistors attached in parallel. CÂU 1 2 3 4 5 6 7 8 9 10
ĐÁP ÁN B A A A B D D C B D
 II. Essay = 12 minutes
EX 
a - Let Q be the heat required to boil water, k is the scaling factor. 
 U 2
- When used only R1: Q k t1 (1)
 R1
- When used only
 U 2
 R2: Q k t2 (2)
 R2
-When using only R1 in serial R2
 U 2
: Q k t3 (3)
 R1 R2
- From (1), (2) and (3) => t3 = t1 + t2 = 50 minutes.
b When using only R1 in parallel
 2 1 1
 R2: Q kU ( )t4 (4)
 R1 R2
 1 1 1
- From (1), (2) và (4) => 
 t4 t1 t2
 t1.t2
 t4 = 12 minutes
 t1 t 2