# If the EMF and the internal resistance of one battery element in the above circuit are 2.5 V and 1.5 Ohm

**If the EMF and the internal resistance of one battery element in the above circuit are 2.5 V and 1.5 Ohm, R1 = 5 Ohm, respectively, and the current through this resistance is 0.85 A, then what will be the resistance R2.**

Given:

EMF1 = 2.5 V;

EMF2 = 1.5 V;

R1 = 5 ohms;

J1 = 0.85 A.

Find: R2.

Decision:

1) First you need to find the total EMF. To do this, you need to multiply EMF1 by three.

Total EMF = 3 * 2.5 = 7.5 V.

2) Next, you need to find the voltage. We need the voltage that will be across the resistor R1. Let’s write down the formula for finding:

U1 = J1 * R1

Let’s substitute the values into it:

U1 = 0.85 * 5 = 4.25 V.

3) Find the voltage drop across the batteries. To do this, subtract the voltage U1 across the resistor R1 from the total EMF.

u = 7.5 – 4.25 = 3.25 B.

4) Find the current. For this we use the following formula: J = u / EMF2.

Substitute the values:

J = 3.25 / 1.5 ≈ 2 A.

5) Next, you need to find the current through the second resistor using the formula:

J2 = 2 – 0.85 = 1.25 A

6) Now we can find the resistance across the second resistor.

We use the formula: R2 = U1 / J2.

Substitute the values we already know and find the answer.

R2 = 4.25 / 1.25 = 3.4 ohm

Answer: 3.4