Đề song ngữ Vật lí 9 - Đề 6 - Trường THCS Đông Tây Hưng (Có đáp án + Ma trận)

 Đề 6
Ex1: a 10-meter long copper conducting-wire (l1=10m) has an resistance R1 and a 5-meter long 
aluminium conducting-wire (l2=5m) has an resistance R2. Compare between R1 and R2 ..
Ex2: a homogeneous conducting-wire, which has the length l, the section S and an 8Ω resistance, is 
bent half in length. Calculate the amount of the new conducting-wire’s resistance.
Ex3: when putting a potential difference into 2 tops of a conducting-wire, we have an electric current 
having an amount of 6mA. If you want the amount of the current to decrease 4mA smaller, the amount 
of the potential difference must be .
Ex4: Two conductors are connected in series, one wire with length l1 = 2m, cross section S1 = 0.5mm². 
The other wire length is l2 = 1m, cross section S2 = 1mm². The relationship of the heat generated on 
each conductor is as follows:
Ex5: we have two resistances: R1=20Ω can stand a current having a maximum intensity of 2A and 
R2=40Ω can stand a current having a maximum intensity of 1,5A. The maximum amount of the 
potential difference can be put into 2 tops of a series circuit consisting of R1 and R2 is .
Ex6: a copper wire, which is 10 meters in length, has a section of 0,2 mm2. Copper has resistivity 
1,7.108. Calculate the amount of the resistance.
Ex7: when putting a bulb into 6V potential difference, the current running through it has the intensity of 
0,2A. Calculate the consumed power of the bulb.
Ex8: we have wires made from same materials. If their length triples and section decreases 3 times, the 
intensity of the wires will be .
Ex9: When placing a 12V voltage at the ends of a winding wire, the current through it is 1.5A. The 
length of the wire used to wind the coil is (Knowing that this type of conductor if 6m long has a resistance of 2 .)
Ex10: an electrical stove having a tag written 220V-1000W is used with the amount of potential 
difference 220V. Calculate the amount of its resistance.
Ex11: Bulb D1 has assessing potential difference U1=1,5V U
and bulb D2 has assessing potential difference U2=6V. When 
they are normally lighting, the amount of their resistances are đ2
 Đ
R1=1,5Ω and R2=8Ω. These two bulbs are put into one 1
rheostat and a potential difference with U=7,5 V. Basing on 
the graph below, how much can we change the amount of 
rheostat so that these two bulb light normally? 
1 .; 2-2; 3-4; 4-110, 0,2A; 5-90; 6-0,85; 7- 1,2A 8-9; 9-24; 10- 44,8
 U1 1,5
EX11:- I1= = = 1(A)
 R1 1,5
 I2= 0,75A 
 U b
 Rb= = 24( ) 
 I b EX11:- To have 2 nomally light bulbs, the intensity of the electric current that runs through each bulb is 
the same as the electric current norm running through each bulb.
 U1 1,5
 I1= = = 1(A)
 R1 1,5
 I2= 0,75A 
 - because the circuit consists of : Đ1nt( Đ2// Rb) , we have:
 Ib= I1- I2= 1- 0,75= 0,25(A)
 Ub= U2= 6V (0,5 đ) 
 - when the rheostat has the resistance, it will be:
 U b
 Rb= = 24( ) 
 I b