ST 404 TEST # 4 Name: ______

CHAPTER 5: Electricity

INSTRUCTIONS: 1. Read each question carefully and answer in the space provided.

  1. Calculators and formula sheets are permitted.
  2. This test has 6 pages and 13 questions.
  3. This test will be marked out of a total of 36 marks.
  4. TIME: 1 HOUR.

SECTION 1: Multiple Choice Questions (12 marks)

1. ____ Electric appliances are made with a wide variety of materials. Some of these

materials are electrical conductors and others are electrical insulators.

Which of the following lists consists of electrical condcutors only?

A) / Aluminum, copper, glass, iron

B) / Aluminum, copper, iron, silver
C) / Ceramic, glass, iron, vinyl
D) / Ceramic, glass, rubber, vinyl

2. ____ The four wires shown below are made out of copper. Which one has the

highest resistance?

A) /
B) /
C) /
D) /
  1. ____ Silk and glass are two electrically neutral materials. Silk can be represented by

and glass by .

After these materials are rubbed together, silk becomes negatively charged and glass becomes positively charged.

Which of the following models may represent silk and glass after these materials have been rubbed together?

A) /
B) /
C) /
D) /

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  1. ____ After being rubbed on hair, a rubber balloon acquires an electrical charge.

When a piece of positively changed cotton is brought close to the balloon, the two objects will attract each other.

What will happen to this balloon if it is brought close to a negatively charged plastic rod, and why?

A) / The balloon will be repelled because it is positively charged.
B) / The balloon will be repelled because it is negatively charged.
C) / The balloon will be attracted because it is positively charged.
D) / The balloon will neither be attracted nor repelled because it is neutral.
  1. ____ Listed below are the characteristics of an electrical circuit consisting of a power source, a light bulb, a switch and a motor (represented by the symbol M in the diagrams below.)
  • The circuit has a device for measuring the potential difference across the light bulb.
  • The circuit has another device for measuring the current intensity in the motor.
  • Only the motor is controlled by a switch.

Which of the following diagrams correctly represents this electrical circuit?

  1. ____ A mystery circuit consists of two light bulbs (L1 and L2), a switch, and a power

supply. The following table shows what happens to both light bulbs when the switch is opened or closed.

Test / Observations
Open the switch / L1 stays on
L2 goes out
Close the switch / L1 stays on
L2 comes on

Which diagram correctly represents this mystery circuit?


A) / / C) /
B) / / D) /

______

SECTION 2: Problem Solving Questions (24 marks)

  1. Match the method of charging an object electrically by writing the letter that corresponds to the appropriate diagram below. (3 marks)


i) ______charging by friction
ii) ______charging by conduction
iii) ______charging by induction

  1. In the space below draw schematic diagram of a circuit consisting of a power supply, two resistors (R1 and R2) connected in parallel, an ammeter measuring the current through R1. (4 marks)
  1. In the laboratory, you are asked to observe the electrical behaviour of certain materials using the following electrostatic list.
Capacity to attract electrons / / Vinyl
Silk
Wool
Glass

You start by rubbing a glass rod with a piece of silk. Then you rub a vinyl ruler with a piece of wool. Lastly, you bring the electrically charged vinyl ruler close to the glass rod.

  1. What is the charge on the glass rod? (1) ______
  2. What is the charge on the vinyl ruler? (1) ______
  3. Will the glass rod and the vinyl ruler attract or repel? (1) ______
  1. Shown below is the rating plate for a lamp that consumed 3000 J of energy when it last used.

100 W
60 Hz
120 V

For how much time was this lamp used? Show all your work. (3 marks)

  1. The following electric circuit consists of a power supply, VT, two resistors (R1 and R2) and a voltmeter . The power supply provides a current of 6 A at a voltage of 12 V. The voltage, V1, across the terminals of resistors R1 is 4 V.

What is the resistance of resistor R1? Show all your work. (3 marks)

  1. The flowing graph show the results of test conducted on two different resistors.

You are asked to assemble an electrical circuit by using the resistor with the lowerresistance.

a)Which resistor should be used to assemble this circuit? Prove your answer with calculations. (2 marks)

b)Calculate the current intensity in this circuit if the voltage is 2V. (2 marks)

  1. A local bakery uses fresh, locally grown apples to make apple pies. In fact, they claim to have the best “Old Fashioned” apples pie in the province.

Two ovens were used to bake the prize winning apple pies:

Oven A: The oven is connected to a 220 V wall outlet that draws a current of 14 A.

It took 1 hour to bake the pies in Oven A.

Oven B: It took 2 hours to bake the pies in a 2400 W oven.

The bakery would like to become more environmentally friendly by consuming less energy.

Which oven should the bakery use in order to be more environmentally friendly?

Justify your answer with calculations. (4 marks)

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