Question

8) An electric iron of resistance 20ohm takes a current of 5A Calculate the heat
developed in 30s and also calculate the potential difference across its ends.​

Answer 1

Answer:

1. Heat developed in 30 seconds = 15000 Joules
2. Potential difference across its ends = 100 Volts

Explanation:

Given that:

• An electric iron of resistance 20 Ω takes a current of 5 A.

To Find:

1. Heat developed in 30 seconds.
2. Potential difference across its ends.

Formula used:

1. H = I²RT
2. V = IR

Where,

• H = Heat
• I = Current = 5 A
• R = Resistance = 20 Ω
• T = Time = 30 seconds
• V = Potential difference

Finding the heat developed in 30 seconds:

⟶ H = (5)² × 20 × 30

⟶ H = 25 × 20 × 30

⟶ H = 15000

∴ Heat developed in 30 seconds = 15000 Joules

Finding the potential difference across its ends:

⟶ V = 5 × 20

⟶ V = 100

∴ Potential difference across its ends = 100 Volts

Answer 2

Answer:

Given :-

Resistance = 20Ω

Current = 5 A

Time = 30 sec

To Find :-

Potential difference

Heat developed

Solution :-

We have

$\sf\begin{cases}\bf Resistance= \frak{20\Omega}\\\bf Current = \frak{5 \: A}\\ \bf Time = \frak{30 \: sec}\end{cases}$

We know that

${\boxed{\red{\pmb{\frak{H = I^2 RT}}}}}$

$\dashrightarrow \rm{Heat \: = {(5)}^{2} \times 20 \times 30}$

$\dashrightarrow \rm{Heat = 25 \times 20 \times 30}$

$\dashrightarrow \rm{Heat \: = 15000 \: J}$

Now,

${\boxed{\red{\pmb{\frak{V = IR}}}}}$

$\dashrightarrow \rm{V = 5 \times 20}$

$\dashrightarrow \rm{V = 100 \: V}$