Question

A 600W toaster, 1200W iron and a 100W bulb are all connected to household 120V circuit. a) find the current drawn by each appliance
b) the resistance of the heating element in the iron
c) the total cost of running all of the appliances non-stop for 5 days if the electricity rate is $0.1 per KW-Hr.

Answer 1

Answer:

(a) %a, 10 A, 0.833 A

(b) 12 ohm

(c) $22.8

Explanation:

Power of toaster, P1 = 600 W

Power of iron, P2 = 1200 W

Power of bulb, P3 = 100 W

V = 120 V

As they are in household circuit, so they are connected in parallel, so the voltage is same for all.

(a) Use the formula P = V x i

Current in toaster, i1 = P1 / V = 600 / 120 = 5 A

Current in iron, i2 = P2 / V = 1200 / 120 = 10 A

Current in bulb, i3 = P3 / V = 100 / 120 = 0.833 A

(b) Resistance of heating element of iron is R2.

V = i2 x R2

120 = 10 x R2

R2 = 12 ohm

(c) Total energy consumed in 24 hours for 5 days

                              = (600 + 1200 + 100) x 24 x 5 = 228000 Wh = 228 KWh

Cost of 1 KWh = $0.1

Cost of 228 KWh = 0.1 x 228 = $22.8

Answer 2

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Answer:

(a). Toaster = 5A

Iron = 10A

Bulb = 0.833A

(b). R2 = 12Ω

(c). $ 22.8

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Explanation:

Given,

Power of Toaster, P1 = 600W

Power of Iron, P2 = 1200W

Power of Bulb, P3 = 100W

Potential difference = 120V

They all are connected in parallel combination because they all are household circuits so that the voltage is same for all appliances in the circuit.

★Solution of (a)

By using the formula of power we can find out the current.

P = V × I

Here, power is directly proportional to the potential difference and electric current flowing through the circuit.

[ .°. I = P / V ]

Here, electric current is inversely proportional to the potential difference and electric current is directly proportional to power.

Current in Toaster, I1 = P1/V = 600/120 = 5A

Current in Iron, I2 = P1/V = 1200/120 = 10A

Current in Bulb, I3 = P1/V = 100/120 = 0.833A

★Solution of (b)

Resistance of Heating coil of Iron

By using the formula of Ohm's Law we can find out the resistance of heating coil of iron.

V = I × R

Here, the potential difference is directly proportional to the current carrying wire and potential difference is directly proportional to the resistance off the wire present in the Iron.

[ .°. R = V/I ]

Here, resistance is directly proportional to the potential difference and resistance is inversely proportional to the electric current.

R = V/I

=> R = 120/10

.°. R = 12Ω

★Solution of (c)

Total consumption of Energy in 24 hours for 5 days = (600W + 1200W + 100W) × 24 hours × 5 days

= 228000Wh

= 228kWh

When the cost of 1kWh = $ 0.1

So,

The cost of 228 kWh = $ 0.1 × 228 = $ 22.8

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