A cell of internal resistant 2.0 ohm and electromotive force (e.m.f.) 1.5 V is connected to a resistor of resistance 3.0 ohm what is the potential difference across 3ohm resistor. .(a) 5 V (b) 1.2 V (c) 0.9 V (d) 0.6 V
Answers
Answer :
- The potential difference across 3 Ω resistor is 0.9 V.
Explanation :
Given :
- Internal resistance of the cell, r = 2 Ω
- Electromotive force (e.m.f) of the cell,ε = 1.5 V
- Resistance in the resistor, R = 3 Ω
To find :
- Potential difference across the 3 Ω resistor, V = ?
Knowledge required :
⠀⠀⠀⠀⠀⠀⠀⠀⠀● Formula for Electromotive force (e.m.f) :
⠀⠀⠀⠀⠀⠀⠀⠀⠀ε = l(R + r)
Where,
- ε = Electromotive force
- l = Current
- R = Load resistance
- r = Internal resistance
⠀⠀⠀⠀⠀⠀⠀⠀⠀● Ohm's law :
⠀⠀⠀⠀⠀⠀⠀⠀⠀V = IR
Where,
- V = Potential difference
- I = Current
- R = Resistance
[Note : In a series circuit, the current passing through each resistor is equivalent to each other]
Solution :
First let us find the current in the circuit :
Using the formula for e.m.f and by substituting the values in it, we get :
⠀⠀⠀=> ε = l(R + r)
⠀⠀⠀=> 1.5 = I(3 + 2)
⠀⠀⠀=> 1.5 = I × 5
⠀⠀⠀=> 1.5/5 = l
⠀⠀⠀=> 0.3 = I
⠀⠀⠀⠀⠀∴ l = 0.3 A
Hence the current in the circuit is 0.3 A.
Now,
Let's find out the potential difference in the 3 Ω resistor:
By using the ohm's law and Substituting the values in it, we get :
⠀⠀⠀=> V = IR
⠀⠀⠀=> V = 0.3 × 3
⠀⠀⠀=> V = 0.9
⠀⠀⠀⠀⠀∴ V = 0.9 V
Therefore,
- Potential difference across the 3 Ω resistor, V = 0.9 V.
Answer:
Firstly we will see the formula.
Here,
E = Electromagnetic force
I = Current
R = Load resistance
r = Internal Resistance
Now,
Ohm's law
V = Potential difference
I = Current
R = Resistance
Now,
Let's solve
Let's find potential difference
We will apply Ohm's law
Therefore, potential difference across 3ohm resistor is 0.9 Volt