The readings on a high resistance voltmeter, when a cell is connected across it, is 2.2 V . When the terminals of cell are also connected to a resistance of 5 ohm the voltmeter reading drops the 1.8 V. Calculate the internal resistance of cell

cell voltage (no load) is 2.2v

cell voltage (5Ω load) is 1.8v

the internal resistance is in series with the cell voltage and the 5Ω load

the drop across the 5Ω load is .4v (2.2 - 1.8)
... so the circuit current is .08a (.4 / 5)

the internal resistance is ... (1.8 / .08)

I = V/R = 1.8/5 = 0.36A = Circuit current.

Ri = (2.2-1.8)/0.36 = 0.4/0.36 = 1.11 Ohms = Internal resistance of cell.

Look for the answer on what I gave you in physics

To calculate the internal resistance of the cell, we can use the formula:

Internal resistance of cell (r) = (Voltage drop across the voltmeter) / (Current passing through the circuit)

First, let's find the voltage drop across the voltmeter. We know that the voltmeter reading is 2.2 V when the cell is connected across it directly, and the reading drops to 1.8 V when a 5 ohm resistance is connected in series with the cell.

Voltage drop across the voltmeter = (Voltmeter reading without the external resistance) - (Voltmeter reading with the external resistance)
= 2.2 V - 1.8 V
= 0.4 V

Next, let's find the current passing through the circuit. We can use Ohm's Law:

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

Since there are two resistances in the circuit (the voltmeter resistance and the external resistance), we can use the total resistance (R_total) to find the total current.

R_total = R_voltmeter + R_external
= high resistance voltmeter + 5 ohm
= high resistance voltmeter + 5 ohm

Using Kirchhoff's Circuit Laws, we can assume that the current passing through the voltmeter is negligible compared to the current passing through the external resistance (since a voltmeter has a very high resistance).

Therefore, we can consider the total current passing through the circuit approximately equal to the current passing through the external resistance.

So, current passing through the circuit (I) = Voltage drop across the voltmeter / Resistance of the external resistor
= 0.4 V / 5 ohm
= 0.08 A

Finally, we can calculate the internal resistance of the cell:

Internal resistance of cell (r) = Voltage drop across the voltmeter / Current passing through the circuit
= 0.4 V / 0.08 A
= 5 ohm

Therefore, the internal resistance of the cell is 5 ohms.