Question

3.The internal resistance of a cell of emf 3V is 10.It is connected to a external resistance of 20Omega.The voltage across the cell will be ^(*) (A) 1V (B) 3V (C) 2V (D) 4V​

Answer 1

Required Answer :

★ Voltage across the cell will be 2V

Option (c) 2V

Given :

• Electromotive force (emf) = 3V
• Internal resistance (r) = 10 Ω
• External resistance (R) = 20 Ω

To find :

• The voltage across the cell (V) = ?

Solution :

Using formula,

• Current (I) = Emf/(R + r)

Substituting the given values :

⇒ I = 3/(20 + 10)

⇒ I = 3/30

⇒ I = 1/10

∴ Current = 0.1 A

Using formula,

• V = I.R

where,

• V = Potential difference or voltage across the cell
• I = Current
• R = Resistance

Substituting the given values :

⇒ V = 0.1 × 20

⇒ V = 2

∴ Voltage across the cell = 2V

Answer 2

Given :-

The internal resistance of a cell of emf 3V is 10.It is connected to an external resistance of 20 Ω

To Find L-

Voltage

Solution :-

Total resistance = Internal resistance + External resistance

⇒ Total resistance = 10 + 20

⇒ Total resistance = 30 Ω

Now

[I = V/R]

⇒ I = 3/30

⇒ I = 0.1 A

Now

V = IR

⇒ V = 0.1 × 30

⇒ V = 3 V

Option B