Question

Три лампы, сопротивление которых 4; 10; и 20 Ом соединены параллельно. Определить ток в каждой из них и в неразветвленной части цепи, если в первой лампе ток равен 2,5 А.

Answer 1

R1=4Ом, R2=10Ом, R3= 20 Ом, I1=2,5 А.
  I2-?  I3-?  I-? 
Соединение параллельное, поэтому напряжение U=I1*R1=2,5*4=10 В, одинаково на всех лампах. Тогда
I2=U/R2=10/10=1 А, I3=U/R3=1/20=0,5 А.
I=I1+I2+I3=2,5+1+0,5= 4 A.

Answer 2

Calculation of Current in Each Lamp

To determine the current in each lamp and in the unbranched part of the circuit, we can use the principles of parallel circuits. In a parallel circuit, the voltage across each component is the same, while the current is divided among the components.

Given that the resistance of the three lamps is 4 Ω, 10 Ω, and 20 Ω, respectively, and the current in the first lamp is 2.5 A, we can calculate the current in each lamp as follows:

1. Calculate the total resistance of the parallel circuit using the formula:

1/R_total = 1/R1 + 1/R2 + 1/R3 Substituting the given resistance values:

1/R_total = 1/4 + 1/10 + 1/20

1/R_total = 5/20 + 2/20 + 1/20

1/R_total = 8/20

R_total = 20/8 = 2.5 Ω

2. Calculate the total current in the circuit using Ohm's Law:

I_total = V_total / R_total

Since the voltage across each lamp is the same, we can use the current in the first lamp (2.5 A) as the total current:

I_total = 2.5 A

3. Calculate the current in each lamp using the formula:

I = I_total * (R_total / R)

For the first lamp (4 Ω):

I1 = 2.5 A * (2.5 Ω / 4 Ω) = 1.5625 A

For the second lamp (10 Ω):

I2 = 2.5 A * (2.5 Ω / 10 Ω) = 0.625 A

For the third lamp (20 Ω):

I3 = 2.5 A * (2.5 Ω / 20 Ω) = 0.3125 A

Calculation of Current in the Unbranched Part of the Circuit

To calculate the current in the unbranched part of the circuit, we need to subtract the current in the first lamp from the total current:

I_unbranched = I_total - I1

Substituting the values:

I_unbranched = 2.5 A - 1.5625 A = 0.9375 A

Therefore, the current in each lamp is approximately: - Lamp 1: 1.5625 A - Lamp 2: 0.625 A - Lamp 3: 0.3125 A

The current in the unbranched part of the circuit is approximately 0.9375 A.

Please note that the calculations provided are based on the given information and assumptions about the circuit.