Question bank IMSO Science 2016

EXPERIMENTAL TEST I: Electrical Circuit

Objectives
- To determine electrical circuit inside a blackbox
- To observe the differences between series and parallel circuits

Theory

In electrical engineering, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another. The mechanism of a switch can be operated manually to control the circuits (for example, a light switch or a keyboard button), by a moving object (such as a door-operated switch), and can be operated by some sensing elements such as pressure or temperature.

There are two types of electrical circuits: open circuit and closed circuit. An open circuit is a discontinuous circuit through which no current can flow. Meanwhile, a closed circuit is a circuit without interruption, providing a continuous path through which current can flow.

You will Need
- A Lamp
- 4 toggle switches
- Batteries
- Wires

What to do

1\. Make sure that the blackbox consists of four switches and a lamp.

2\. Move Switch 1 (S1) to an up position.

3\. Observe the lamp condition.

4\. Move Switch 1 (S1) to a down position.

5\. Write down the data in Table 1.


| Switch | Switch Position | Lamp Condition | Switch Position | Lamp Condition |
| --- | --- | --- | --- | --- |
| S1 | Up | \_\_\_\_\_ | Down | \_\_\_\_\_ |
| S2 | Up | \_\_\_\_\_ | Down | \_\_\_\_\_ |
| S3 | Up | \_\_\_\_\_ | Down | \_\_\_\_\_ |
| S4 | Up | \_\_\_\_\_ | Down | \_\_\_\_\_ |

6\. Repeat steps 1-5 by using S2, S3, and S4.

7\. Move Switch 1 (S1) and Switch 2 (S2) to an up position.

8\. Observe the lamp condition.

9\. Move Switch 1 (S1) and Switch 2 (S2) to a down position.

10\. Write down the data in Table 2.


| Switch | Switch Position | Lamp Condition |
| --- | --- | --- |
| S1 and S2 | Up | \_\_\_\_\_ |
| S1 and S3 | Up | \_\_\_\_\_ |
| S2 and S3 | Up | \_\_\_\_\_ |

11\. Repeat steps 7-10 by using (S1 and S2), (S1 and S3), (S2 and S3).

12\. According to the data in Table 1, draw an electrical circuit diagram when one switch is closed and the lamp is lit up by inserting switch, lamp, battery, and wire. Circuit 1:

13\. According to the data in Table 2, draw an electrical circuit diagram when the two switches are closed and the lamp is lit up by inserting switch, lamp, battery, and wire. Circuit 2; Circuit 3; Circuit 4:

14\. Draw an electrical circuit by combining three electrical circuit diagram from step 13. Circuit 5:

15\. Draw an electrical circuit by combining circuit diagrams from step 12 and step 14. Circuit 6:


Editorial clarification: keep untested switches in the down position when testing a selected switch or pair. Record actual observations in the blank tables; reference answers appear only in the solution. Practical-work marks (22) are printed in the supplied key rather than in the question paper.

Safety: use only the supplied low-voltage battery apparatus under adult/teacher supervision. Never connect this experiment to mains electricity. Disconnect power before changing wires or cleaning probes; avoid short circuits, hot batteries and sharp electrodes. Keep hands dry, keep liquids away from electrical connections, and do not eat the tested vegetables.

TEST I Question 1. (1 point) According to the experimental results, which one is series and parallel connection?

TEST I Question 2. (1 point) Draw some arrows that represent electrical current on the circuit below

TEST I Question 3. (1 point) Draw some arrows that represent electron current on the circuit below

TEST I Question 4. (1 point) The following figure shows schematic diagram of the battery

Which point has higher voltage?

TEST I Question 5. (3 points) Complete the table below by giving the direction of electrical current and electron current [(+) = positive charge and (-) = negative charge]

TEST I Question 6. (2 points) Two charged bodies, 10 C and 30 C respectively, are connected by a conductor. How much is their charge after equilibrium state?

EXPERIMENTAL TEST II: Electrical Conductivity in Certain Vegetables

Some organisms have an ability to conduct electricity. In this experiment, the electrical conductivity in various vegetables; cucumber, eggplant, and carrot will be measured.

Objectives
1. To measure electrical conductivity in cucumber, eggplant, and carrot.
2. To measure and compare electrical conductivity in a vegetables based on different electrode distances.

You will need
- Electrical “Blackbox”
- Cucumber
- Eggplant
- Carrot

What to do
1. Take a wire, then plug the base probe to the hole in the Blackbox apparatus.
2. Take a cucumber, then put it on an experiment chamber. Make sure the cucumber is located at the end of closed experiment chamber space. Press the cucumber so that the electrode needle sticks tightly with the cucumber.
3. Plug the tip point probe of red wire into the hole number 1 which is located on the side of an experiment chamber.
4. Write down the value of the gauge meter in Table 1 in your WORKSHEET
5. Repeat steps 3-4, to hole number 2, hole number 3, hole number 4, and hole number 5 which are located on the side of an experiment chamber.
6. Discard the cucumber from the experiment chamber, then clean the electrode needle and electrode probe with tissue papers.
7. Repeat steps 2-6 by with egg plant and carrot.
8. Make sure all of your data are written in your WORKSHEET.

Question 1. (3 points) Make a graph based on your data in Table 1. Give a legend in your graph.

Editorial blank recording table: the separate Test II worksheet and measured data were not supplied. Enter actual meter readings and units, and measure actual electrode separations if available. Do not treat a hole number as a known distance.

| Vegetable | Hole 1 | Hole 2 | Hole 3 | Hole 4 | Hole 5 |
| --- | --- | --- | --- | --- | --- |
| Cucumber | \_\_\_\_\_ | \_\_\_\_\_ | \_\_\_\_\_ | \_\_\_\_\_ | \_\_\_\_\_ |
| Eggplant | \_\_\_\_\_ | \_\_\_\_\_ | \_\_\_\_\_ | \_\_\_\_\_ | \_\_\_\_\_ |
| Carrot | \_\_\_\_\_ | \_\_\_\_\_ | \_\_\_\_\_ | \_\_\_\_\_ | \_\_\_\_\_ |

Safety: use only the supplied low-voltage battery apparatus under adult/teacher supervision. Never connect this experiment to mains electricity. Disconnect power before changing wires or cleaning probes; avoid short circuits, hot batteries and sharp electrodes. Keep hands dry, keep liquids away from electrical connections, and do not eat the tested vegetables.

TEST II Question 2. (1 point) Based on your data, which vegetable has the highest electrical conductivity?

TEST II Question 3. (1 point) On every vegetable tested, which holes number gives the highest value of electrical conductivity?

TEST II Question 4. (2 points)Why is there a difference of electrical conductivity between different distances of electrode?

TEST II Question 5. The table below show the data of water and electrolyte content in each vegetables that is used in the experiment.

| Vegetables | Water content (%) |
| --- | --- |
| Cucumber | 95 |
| Eggplant | 91 |
| Carrot | 87 |

a. (1 point) Which part of the vegetable that has ability to store the water?

b. (1 point) Mention 3 factors influence electrical conductivity measurement in vegetables?

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| Fruit juice 1 | Fruit juice 2 | Fruit juice 3 | Fruit juice 4 |
| --- | --- | --- | --- |
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