3.2 Why a light bulb lights up

Technology

Grade 6

Systems and control: an electrical shock

Module 14

Why does a light bulb in a circuit light up?

Background information

The electrical energy is converted into heat energy, which causes the glow (incandescence). This happens because the wolfram wire (filament) in the bulb becomes hot because of its resistance to the electric current. The glass globe is filled with gas and this keeps the wire from being burnt out. Apparatus like light bulbs, loudspeakers and stove plates that generate light, sound and heat also offer a type of resistance to the electrical current. An electric engine is a motor that generates motion.

Assignment 1

1. Build the simple electric circuit shown in the sketch.

Draw a diagram to illustrate the circuit.

1. Add another light bulb in series in the electric circuit. Is the light emitted from the light bulb brighter or duller?

Supply the reason by underlining the correct word: The energy that is available for each light bulb is (halved / doubled).

What will happen if one of the light bulbs stops working / breaks?

1. Add another light bulb to the circuit in parallel, in circuit (a). Do both light bulbs glow equally brightly?

Supply the reason by underlining the correct word: The amount of energy supplied to each of the light bulbs is (the same / different).

What will happen if one of the light bulbs stops working / breaks?

1. Application: Underline the correct expression to make the statement correct: The lights in our house remain bright, even if all of them are switched on at the same time. This is because they are connected (in series / in parallel).
2. Touch the light bulbs.

Are they warm or cold to the touch?

A light bulb that emits light therefore supplies light energy, as well as______________________ energy.

[LO 1.3

Assessment

Learning Outcomes(LOs)

LO 1

TECHNOLOGICAL PROCESSES AND SKILLS

The learner will be able to apply technological processes and skills ethically and responsibly using appropriate information and communication technologies

Assessment Standards(ASs)

We know this when the learner:

1.3 performs, where appropriate, scientific investigations about concepts relevant to a problem, need or opportunity using science process skills;

Memorandum

Assignment 1

(a)

(b) weaker

Halved

The current will not flow

(c) Yes

The same

The other bulb will keep on burning

(d) parallel

(e) warm

Warmth