Educational worksheet on electricity and circuits for students, including multiple-choice questions and a diagram to complete.

Problem Analysis and Solution

The provided worksheet focuses on Electricity and Circuits. Let's solve each part step by step.

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#### Section 1: Choose the correct answer

##### Question A
- Which of the following is the source of electricity in a mobile phone?
- Options:
- a. Solar cell
- b. Charger
- c. Primary cell
- d. Secondary cell

Explanation:
- A mobile phone typically uses a rechargeable battery as its power source. This type of battery is called a secondary cell because it can be recharged multiple times.
- A primary cell is a non-rechargeable battery, which is not used in mobile phones.
- A solar cell converts sunlight into electricity but is not the primary power source for mobile phones.
- A charger is used to recharge the battery but is not the source of electricity itself.

Correct Answer: d. Secondary cell

##### Question B
- Which device is used to make or break a circuit?
- Options:
- a. Closed circuit
- b. Insulator
- c. Switch
- d. Open circuit

Explanation:
- A switch is a device that controls the flow of electric current in a circuit. It can either allow current to flow (closed circuit) or stop it (open circuit).
- A closed circuit refers to a complete path for current to flow, but it is not a device.
- An insulator is a material that does not conduct electricity, so it cannot make or break a circuit.
- An open circuit is a condition where the circuit is not complete, but it is not a device.

Correct Answer: c. Switch

##### Question C
- LED stands for:
- Options:
- a. Light Emulation diode
- b. Light Emitting diode
- c. Load Emitting disc
- d. Load Emulation digital

Explanation:
- LED stands for Light Emitting Diode. It is a semiconductor device that emits light when an electric current passes through it.
- The other options are incorrect:
- "Light Emulation diode" is not a standard term.
- "Load Emitting disc" and "Load Emulation digital" are unrelated to LEDs.

Correct Answer: b. Light Emitting diode

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#### Section 2: Complete the diagram so that the bulb can start to glow

The diagram shows a light bulb and a battery. To make the bulb glow, a complete circuit must be formed. This requires connecting the positive terminal of the battery to one terminal of the bulb and the negative terminal of the battery to the other terminal of the bulb.

Solution:
- Draw a wire connecting the positive terminal of the battery to one terminal of the bulb.
- Draw another wire connecting the negative terminal of the battery to the other terminal of the bulb.

This completes the circuit, allowing current to flow and making the bulb glow.

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#### Section 3: Give one word answer for the following questions

##### Question a
- Device that converts chemical energy to electricity.

Explanation:
- A device that converts chemical energy into electrical energy is a battery. Batteries store chemical energy and release it as electrical energy when connected to a circuit.

Answer: Battery

##### Question b
- A material that does not allow electric current to pass through it.

Explanation:
- A material that does not allow electric current to pass through it is called an insulator. Examples include rubber, plastic, and glass.

Answer: Insulator

##### Question c
- A cell that cannot be recharged.

Explanation:
- A cell that cannot be recharged is called a primary cell. These cells are disposable and are used once before being discarded.

Answer: Primary cell

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#### Section 4: You switch on an electric torch, but the bulb does not glow. Become a detective and solve the mystery.

##### Question
- List three possible reasons why the bulb does not glow.

Possible Reasons:
1. Dead Battery: The battery may be drained or not providing enough power to the bulb.
2. Loose Connection: There might be a loose connection between the battery terminals and the bulb, preventing the current from flowing.
3. Burnt-Out Bulb: The bulb itself may be burnt out or damaged, preventing it from glowing even if the circuit is complete.

Answer:
1. Dead battery
2. Loose connection
3. Burnt-out bulb

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Final Answers:

1. Choose the correct answer:
- A. d. Secondary cell
- B. c. Switch
- C. b. Light Emitting diode

2. Complete the diagram:
- Draw wires connecting the battery terminals to the bulb terminals to form a complete circuit.

3. Give one word answer:
- a. Battery
- b. Insulator
- c. Primary cell

4. Reasons why the bulb does not glow:
- 1. Dead battery
- 2. Loose connection
- 3. Burnt-out bulb

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Final Boxed Answers:

1. A. (d), B. (c), C. (b)
2. [Diagram completed with wires connecting the battery to the bulb]
3. a. Battery, b. Insulator, c. Primary cell
4. a. Dead battery, b. Loose connection, c. Burnt-out bulb

\boxed{See above for detailed solutions}