Question

В свинцовой проволоке плавкого предохранителя сечением 0,21мм^2 течёт ток 10 А. Какова длина этой проволоки, если напряжение на ней равно 0,42 В?Удельное сопротивление свинца равно 0,21х10^-6 Ом*м

Answer 1

Решение на фотографии 

Answer 2

Calculating the Length of the Lead Wire

To calculate the length of the lead wire, we can use the formula for resistance:

Resistance (R) = (Specific Resistance * Length) / Cross-sectional Area

Given: - Current (I) = 10 A - Voltage (V) = 0.42 V - Cross-sectional Area (A) = 0.21 mm^2 - Specific Resistance of Lead (ρ) = 0.21 x 10^-6 Ω*m

We can rearrange the formula to solve for the length (L):

Length (L) = (Resistance * Cross-sectional Area) / Specific Resistance

First, let's calculate the resistance using Ohm's law:

Resistance (R) = Voltage (V) / Current (I)

Resistance (R) = 0.42 V / 10 A

Resistance (R) = 0.042 Ω

Now, we can use the formula to find the length:

Length (L) = (0.042 Ω * 0.21 x 10^-6 m^2) / 0.21 x 10^-6 Ω*m

Length (L) = 0.042 m

So, the length of the lead wire is 0.042 meters.

This calculation assumes that the lead wire has a uniform cross-sectional area and that the specific resistance of lead is constant throughout the wire.