A cell of emf 2v and internal resistance of 1ohms passes a current through an external load of 9ohms.calculate the potential difference across the cell
1/10 of the voltage will be lost in internal resistance, so output voltage will be 2*9/10 Volts=1.8volts
Now the long way.
current=2v/10ohms=.2amps
voltage lost in internal resistance: .2*1=.2volts
terminal voltage=2-.2=1.8volts
a cell has an e.m.f of 3v when it is connected across a resistor of resistance 4 a current of 0.5 a passes through the circuit. Calculate the internal resistance of the cell.
Good
0.2v
To calculate the internal resistance of the cell, we need to use Ohm's law:
V = IR
where V is the voltage across the resistor, I is the current passing through the circuit, and R is the resistance of the resistor.
In this case, V = 3V, I = 0.5A, and R = 4Ω. Therefore:
3V = 0.5A x 4Ω + V_internal
Simplifying:
3V = 2V + V_internal
V_internal = 1V
Now we can use another formula:
V_internal = I_internal x R_internal
where I_internal is the current passing through the internal resistance of the cell, and R_internal is the internal resistance itself.
We can rearrange this to get:
R_internal = V_internal / I_internal
We don't know the value of I_internal, but we can use Kirchhoff's circuit laws to find it. The current passing through the external resistor is the same as the current passing through the internal resistance and the cell. Therefore:
I_total = I_internal + I_external
I_total = 0.5A
I_external = 0.5A
Therefore:
I_internal = I_total - I_external = 0A
This means that there is no current passing through the internal resistance of the cell. Therefore, the internal resistance is infinite.
In summary, the internal resistance of the cell is infinite.
To calculate the potential difference across the cell, you need to take into account the internal resistance of the cell and the resistance of the external load.
The potential difference across the cell can be found using Ohm's Law, which states that the potential difference (V) is equal to the current (I) multiplied by the total resistance (R).
In this case, the total resistance is the sum of the internal resistance of the cell (r) and the resistance of the external load (R). So, the equation can be written as:
V = I * (r + R)
Given:
EMF of the cell (E) = 2V
Internal resistance of the cell (r) = 1Ω
Resistance of the external load (R) = 9Ω
To find the current (I) flowing through the circuit, you can use Ohm's Law again:
I = E / (r + R)
Substituting the given values:
I = 2V / (1Ω + 9Ω)
I = 2V / 10Ω
I = 0.2 A (Amperes)
Now, you can substitute the calculated current into the equation for potential difference:
V = I * (r + R)
V = 0.2 A * (1Ω + 9Ω)
V = 0.2 A * 10Ω
V = 2 V
Therefore, the potential difference across the cell is 2 volts.