Question

An electric iron of resistance 20 12 takes a current of 5 A. Calculate the
heat developed in 30 s.​

Answer 1

Appropriate Question :

An electric iron of resistance 20 Ω takes a current of 5 A. Calculate the heat developed in 30 s.

Required Answer :

♦ Heat developed in the conductor in 30 seconds = 15,000 J

Given :

→ Resistance of an electric iron = 20 Ω

→ Current = 5 A

→ Time = 30 s

To find :

→ The heat developed in 30 seconds.

Solution :

Formula to find the heat developed in a conductor :-

• H = I²Rt [Joule's equation of electric heating.]

where,

• H denotes the heat developed.
• I denotes the current in the conductor.
• R denotes the resistance.
• t denotes the time.

we have,

• I = 5 A
• R = 20 Ω
• t = 30 s

Substituting the given values :-

→ Heat developed = (5)²(20)(30)

→ Heat developed = 5 × 5 × 20 × 30

→ Heat developed = 15,000

Therefore, the heat developed = 15,000 J

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Some related formulae :-

• I = Q ÷ T
• Q = I × T
• V = I × R
• R = V ÷ I

where,

• I denotes the current.
• Q denotes the charge.
• T denotes the time.
• V denotes the potential difference.