Question

Помогите!Найти ЭДС и внутреннее сопротивление гальванического элемента, если при одном положении движка реостата ток в цепи равен 1.2 А и напряжение на клеммах элемента 1.2 В, а при другом положении — соответственно 2 А и 0.8 В

Answer 1

Гальванический элемент представляет собой единое целое, поэтому напряжение на его клеммах - это также напряжение на реостате.
По закону Ома для участка цепи I=U/R.
При первом положении ползунка реостата его сопротивление
R1=U1/I1=1.2/1.2=1(Ом).
При втором положении R2=U2/I2=0.8/2=0.4 (Ом).
По закону Ома для полной цепи I=E/(R+r), где r - внутреннее сопротивление источника тока.
Отсюда E=I*(R+r), и поскольку E не меняется, получаем уравнение:
I1*(R1+r)=I2*(R2+r). Подставляя известные величины, получаем:
1.2*(1+r)=2*(0.4+r); 1.2+1.2r=0.8+2r; 0.8r=0.4 ⇒ r=0.5 (Ом)
Тогда E=I1*(R1+r)=1.2*(1+0.5)=1.2*1.5=1.8 (В).
Ответ: E=1.8 B, r=0.5 Ом

Answer 2

Finding the EMF and Internal Resistance of a Galvanic Cell

To find the electromotive force (EMF) and internal resistance of a galvanic cell, we can use the given information about the current and voltage in the circuit.

Let's denote the EMF of the galvanic cell as E and the internal resistance as r.

Given: - Current in the circuit when the rheostat is in one position: I1 = 1.2 A - Voltage across the terminals of the galvanic cell in this position: U1 = 1.2 V - Current in the circuit when the rheostat is in another position: I2 = 2 A - Voltage across the terminals of the galvanic cell in this position: U2 = 0.8 V

We can use Ohm's Law to relate the current, voltage, and resistance in the circuit:

U = E - Ir (Equation 1)

where: - U is the voltage across the terminals of the galvanic cell, - E is the electromotive force (EMF) of the galvanic cell, - I is the current in the circuit, and - r is the internal resistance of the galvanic cell.

We have two sets of values for current and voltage, so we can set up two equations using Equation 1:

For the first position: U1 = E - I1r (Equation 2)

For the second position: U2 = E - I2r (Equation 3)

To solve for E and r, we can subtract Equation 3 from Equation 2:

U1 - U2 = (E - I1r) - (E - I2r)

Simplifying the equation:

U1 - U2 = E - I1r - E + I2r

U1 - U2 = I2r - I1r

U1 - U2 = (I2 - I1)r

Now we can solve for r:

r = (U1 - U2) / (I2 - I1) (Equation 4)

To find E, we can substitute the value of r into Equation 2:

U1 = E - I1r

E = U1 + I1r (Equation 5)

Using the given values, we can calculate E and r:

Substituting the values into Equation 4: r = (1.2 - 0.8) / (2 - 1.2) = 0.4 / 0.8 = 0.5 Ω

Substituting the values into Equation 5: E = 1.2 + 1.2 * 0.5 = 1.2 + 0.6 = 1.8 V

Therefore, the electromotive force (EMF) of the galvanic cell is 1.8 V and the internal resistance is 0.5 Ω.

Please note that the provided search results did not contain specific information related to this particular problem. The solution was derived using the principles of Ohm's Law and the given information.