Question

Три лампочки сопротивлением 230 Ом, 345 Ом и 690 Ом соединены параллельно и включены в сеть, сила тока в которой 2 А. Под каким напряжением работают лампы?

Answer 1

За формулой:
U=IR
Потом R=1:R1+1:R2 +...
 

Answer 2

Calculation of Total Resistance

To determine the voltage at which the bulbs operate, we first need to calculate the total resistance of the circuit. The three bulbs are connected in parallel, which means that the voltage across each bulb is the same. The formula to calculate the total resistance of parallel resistors is:

1/R_total = 1/R1 + 1/R2 + 1/R3

Given the resistances of the bulbs: - R1 = 230 Ω - R2 = 345 Ω - R3 = 690 Ω

Let's calculate the total resistance:

1/R_total = 1/230 + 1/345 + 1/690

To simplify the calculation, we can find the least common multiple (LCM) of the denominators:

LCM(230, 345, 690) = 690

Now we can rewrite the equation using the LCM:

1/R_total = 3/690 + 2/690 + 1/690

1/R_total = 6/690

R_total = 690/6

R_total = 115 Ω

Calculation of Current

We are given that the current in the circuit is 2 A.

Calculation of Voltage

To calculate the voltage at which the bulbs operate, we can use Ohm's Law, which states that the voltage across a resistor is equal to the current through it multiplied by its resistance:

V = I * R

For each bulb, we can calculate the voltage:

- For bulb 1 (R1 = 230 Ω): V1 = 2 A * 230 Ω = 460 V

- For bulb 2 (R2 = 345 Ω): V2 = 2 A * 345 Ω = 690 V

- For bulb 3 (R3 = 690 Ω): V3 = 2 A * 690 Ω = 1380 V

Therefore, the bulbs operate at the following voltages: - Bulb 1: 460 V - Bulb 2: 690 V - Bulb 3: 1380 V

Please note that these calculations assume an ideal circuit with no losses or other factors that may affect the actual voltage across the bulbs.