Question

An electric kettle rated as 1200 W at 220 V and a toaster rated at 1000 W at 220 V are both connected in parallel to a source of 220 V. If the fuse connected to the source blows when the current exceeds 9.0 A, can both appliances be used at the same time? Illustrate your answer with calculations.

Answer 1

Given: Power rating (P₁) = 1200 W

Power rating (P₂) = 1000 W

Voltage supply (V) = 220 V

We know that,

P = VI

⇒ I = `P/V`

I₁ = `P_1/V`

⇒ I₁ = `1200/220`

⇒ I₁ = 5.45 A

I₂ = `P_2/V`

⇒ I₂ = `1000/220`

⇒ I₂ = 4.55 A

I_total = I₁ + I₂

I_total = 5.45 + 4.55

I_total = 10.0 A

P_total = P1 + P2

P_total = 1200 + 1000

P_total = 2200

Dividing it by the source voltage 220 V, we get 10.0 A.

Both appliances cannot be operated simultaneously because their total combined current draw of 10.0 A is strictly greater than the maximum 9.0 A threshold handled by the main safety fuse, causing it to blow immediately.