# Electricity (problem solving) - PowerPoint PPT Presentation

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Electricity (problem solving). Prepared by: Edward A. Mirador San Bartolome High School. 1. How much electrical energy is used up in 2 hours by a 220 V electric stove whose power rating is 3 kW ?. A – 3 kWh B – 6 kWh C – 440 kWh D – 660 kWh. Correct !. E = P x t. Congratulations.

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Electricity (problem solving)

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## Electricity(problem solving)

Prepared by:

San Bartolome High School

• A – 3 kWh

• B – 6 kWh

• C – 440 kWh

• D – 660 kWh

## Correct !

E = P x t

Congratulations

2. What is the total amount of electrical energy consumed by three 100W lamps and five 50W lamps if these are used for 30 days at an average of five hours daily?

• A – 0.825 kWh

• B – 8.25 kWh

• C – 82.5 kWh

• D – 825.0 kWh

## Correct !

E = P x t

300W x 150h = 45kW

250W x 150h = 37.5kW

+ 82.5kW

Congratulations

• A – 0.45 A

• B – 2.2 A

• C – 4.5 A

• D – 22.0 A

I = P / V

## Correct !

Congratulations

4. An electric meter showed an increase in reading of 8 kWh after a flat iron was used. About how many hours was it used if it carried a 5 A current from a 220 V line?

• A – 1

• B – 4

• C – 7

• D – 40

## Correct !

P = V x I

t = E / P

Congratulations

5. Fifty identical Christmas lights are connected in series and plugged into a 220V line. Neglecting wire resistance, what is the voltage across each bulb?

• A – 2.2 V

• B – 4.4 V

• C – 110 V

• D – 220 V

.

## Correct !

Vtotal= V1 + V2 + V3+…+ Vn

Since R is identical so as the V across

Therefore V = Vtotal / n

Congratulations

6. Which of the following correctly ranks the equivalent resistance of the three 100 resistors arranged as shown below from greatest to least value??

• A – 2-1-4-3

• B – 2-3-1-4

• C – 2-3-4-1

• D – 2-4-1-3

.

## Correct !

1. RT = 1/3 R3. RT = 3/2 R

2. RT = 3 R4. RT = 2/3 R

Congratulations