Conduction, convection or radiation worksheet - Free Printable

Let's solve this step-by-step by identifying whether each image represents conduction, convection, or radiation. Here's a quick recap of the three methods of heat transfer:

1. Conduction: Heat transfer through direct contact between materials (usually solids).
2. Convection: Heat transfer through fluids (liquids or gases) via movement of heated particles.
3. Radiation: Heat transfer through electromagnetic waves (does not require a medium).

Now, let’s go through each image:

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1. Toaster

- The bread is heated by electric heating elements that touch the bread.
- Heat is transferred directly through contact.
- ✔ Conduction

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2. Hair Dryer

- Blows hot air onto hair.
- The air heats up and moves to transfer heat.
- This involves movement of hot air.
- ✔ Convection

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3. Iron

- Heats clothes by direct contact with a hot metal plate.
- The heat is transferred from the iron to the fabric.
- ✔ Conduction

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4. Campfire

- Fire emits heat in all directions as infrared radiation.
- You feel warmth even without touching it.
- ✔ Radiation

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5. Space Heater

- Heats the surrounding air, which rises and circulates.
- Warm air moves upward, cool air sinks — creating convection currents.
- ✔ Convection

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6. Person sunbathing

- Sunlight warms the person’s skin through electromagnetic waves.
- No physical contact; heat comes from the Sun.
- ✔ Radiation

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7. Barbecue Grill

- Food is cooked over flames, but heat reaches food through hot air and radiant heat from coals.
- However, since it's an open flame and air circulates, both convection and radiation are involved.
- But the dominant method here is radiation from the fire.
- ✔ Radiation (primary), though some convection occurs.

> In most educational contexts, grilling is considered radiation due to direct infrared heat from flames/coals.

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8. Oven (with bread inside)

- Air inside the oven gets hot and circulates.
- Also, the oven walls radiate heat.
- But the main mechanism for cooking inside an oven is hot air circulation.
- ✔ Convection

> Note: Modern ovens may use radiation too, but standard baking relies on convection.

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9. Cup of Coffee

- The steam rising indicates evaporation, but the cup transfers heat to your hand.
- If you're holding the cup, heat travels from the cup to your hand via direct contact.
- ✔ Conduction

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10. Pan on Fire

- The pan is placed directly on the flame.
- Heat goes from the flame → pan → food.
- Direct contact between flame and pan (but flame = radiation? Wait…)
- Actually, the flame heats the pan primarily by radiation and convection, but the pan conducts heat to the food.
- However, the main mode of heat transfer from the flame to the pan is radiation and convection.
- But since the pan is in direct contact with the flame, and we’re considering how the pan heats up:
- The flame radiates heat to the pan.
- Hot gases also convect heat.
- But radiation is dominant in open flames.
- ✔ Radiation (primary)

> Some sources say "conduction" if the pan is touching the burner, but here it’s shown over open flame → Radiation

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11. Soldering Iron

- Heats metal by direct contact.
- The tip touches the solder and circuit board.
- ✔ Conduction

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12. Air Fryer (showing cold air in, hot air out)

- Uses rapid air circulation to cook food.
- Air is heated and blown around the food.
- ✔ Convection

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Final Answers:

| # | Image | Method |
|---|------|--------|
| 1 | Toaster | Conduction |
| 2 | Hair Dryer | Convection |
| 3 | Iron | Conduction |
| 4 | Campfire | Radiation |
| 5 | Space Heater | Convection |
| 6 | Sunbathing | Radiation |
| 7 | Barbecue | Radiation |
| 8 | Oven | Convection |
| 9 | Cup of Coffee | Conduction |
| 10 | Pan on Fire | Radiation |
| 11 | Soldering Iron | Conduction |
| 12 | Air Fryer | Convection |

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✔ Summary:
- Conduction: 1, 3, 9, 11
- Convection: 2, 5, 8, 12
- Radiation: 4, 6, 7, 10

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