# Energy In Electrical Circuits Test -2

## Energy calculations in electrical circuits. Calculation of energy price that consumed in electrical circuits. Concept of kWh and horsepower. Relation of the power and energy. Solved questions -2.

Question – 1

An electric motor operates by voltage of 380 V in an electrical circuit.

The resistance of this motor is 95 Ohm

How many horsepower is the power of this motor?

(1 hp = 746 W)

A) 6             B) 5.12           C) 4.32

D) 3.78        E) 2.04

Question – 2 In the circuit shown in the figure, there are a voltage source of 100 Volt and two heater that have resistors of R1 = 18 Ohm and R2 = 26 Ohm. The heaters are in water-filled containers.

The masses of water in each the containers is 600 grams. The temperatures of the waters are equal and 10 degrees.

The switch A is switched off and flows current through in the circuit during 20 minutes.

Then the switch A is switched on.

In the last case, temperature in the container K is T1, and temperature in the container L is T2.

The T1 and T2 temperatures has given correctly in which of the following.

(cwater = 4 J/g °C)

A) T1 = 45, T2 = 66

B) T1 = 66,25, T2 = 45,25

C) T1 = 66,25, T2 = 91,25

D) T1 = 56,75, T2 = 66,55

E) T1 = 72,75, T2 = 99,15

Question -3 In the circuit in the figure, resistance of the L1 lamp is 160 Ω, resistance of the L2 lamp is 200 Ω, and resistance of the L3 lamp is 220 Ω.

The Energy used by the lamps in 1 hour is

A) 1072.98 kJ

B) 975.56 kJ

C) 765.25 kJ

D) 687.96 kJ

E) 515.36 kJ

Question – 4 In the circuit shown in the figure, resistance of the L1 lamp is 220 Ω, and resistance of the L2 lamp is 100 Ω.

Cost of 1 kWh energy is 0.2 USD.

These lamps are operated during 8 hours in one day.

1 month cost (30 days) of L1 lamp is X , and 1 month (30 days) cost of L2 lamp is Y.

What is the result of the operation of Y – X?

A) 5.8 USD

B) 3.16 USD

C) 2.64 USD

D) 2.36 USD

E) 1.8 USD

Question – 5

An appliance of 5 horsepower operates by the voltage of 380 Volt.

How many amperes current does this appliance draw from the source ?

(1 hp = 746 W)

A)9.8              B) 8.4              C) 7.5

E) 6.3             E) 5.5

Question – 6 In the circuit in the figure, R1 = 6 Ω, R2 = 4 Ω, R3 = 3 Ω, R4 = 3 Ω, R5 = 12 Ω, R6 = 4 Ω.

Energy consumed during time t in the resistor R1 is E1.

Energy consumed during time t in the resistor R5 is E5.

The ratio of E1/E5 is

A) 0.5           B) 1             C) 2

D) 2.5          E) 4

Question – 7

in a house there are a washing machine, a television, two bulbs and a refrigerator.

Power of the washing machine is 2000 W, power of the TV is 30 W, Powers of the each other bulbs are 75 W, and power of the refrigerator is 100 W.

In this home, on average, the washing machine operates during 1 hour in a day, the TV operates during 5 hour in a day, the bulbs operates during 6 hours in one day, the refrigerator operates during 8 hours in a day.

Cost of 1 kWh energy is 0.2 USD.

How much Dollars does monthly (30 days) energy cost of this house?

A) 50               B) 42                C) 36.5

D) 32.8            E) 23.1

Question – 8 How much energy does the circuit shown in the figure consume in 15 minutes?

A) 120 kWh

B) 90 kWh

C) 75 kWh

D) 60 kWh

E) 45 kWh

Solutions Of The Electrical Energy Test-2

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December 12 2018

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