Q3 Science Worksheet 8 - Heat Transfer worksheet - Free Printable

Here's the solution to the worksheet, with explanations for each answer:

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1. Heating food in a microwave oven.
✔ Answer: RADIATION

Explanation:
Microwave ovens use electromagnetic waves (microwaves) to heat food. These waves travel through space and are absorbed by water molecules in the food, causing them to vibrate and generate heat. This is radiation, because heat is transferred via electromagnetic waves without needing direct contact or a medium.

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2. The butter on top of the pancake melted.
✔ Answer: CONDUCTION

Explanation:
The hot pancake (which was heated by the pan) is in direct contact with the butter. Heat flows from the hotter pancake into the cooler butter through physical contact — this is conduction.

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3. Your wrinkled shirt flattened out after ironing it.
✔ Answer: CONDUCTION

Explanation:
The hot metal plate of the iron touches the fabric directly. Heat transfers from the iron to the shirt fibers through direct contact, smoothing out wrinkles. Again, this is conduction.

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4. You feel the warmth of the fireplace even if you are sitting on the sofa.
✔ Answer: RADIATION

Explanation:
You’re not touching the fire, and air isn’t circulating hot air directly to you (that would be convection). Instead, infrared radiation travels through the air from the fire to your skin — that’s radiation.

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5. You feel hot after reading for a long time under a lamp.
✔ Answer: RADIATION

Explanation:
Incandescent or halogen lamps emit visible light and infrared radiation (heat). Even though the bulb may not touch you, you absorb the radiant energy — this is radiation. (Note: Some heat may also come from convection of warm air rising, but the primary mechanism for feeling heat *directly* from a lamp is radiation.)

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6. Roasting pig over fire.
✔ Answer: RADIATION

Explanation:
The pig is suspended above the fire, not touching it. Heat reaches the pig primarily through infrared radiation emitted by the flames and hot coals. While some convection (rising hot air) may play a role, the dominant method of heat transfer in roasting meat over an open fire is radiation.

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✔ Final Answers:

1. RADIATION
2. CONDUCTION
3. CONDUCTION
4. RADIATION
5. RADIATION
6. RADIATION

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