GCSE Physics Revision "Required Practical 10: Infrared"

Summary

This video demonstrates a practical investigation into how different surfaces absorb and emit infrared radiation. By using a Lesley’s Cube, infrared detectors, and metal plates painted with various surfaces (matte black, shiny black, white, and shiny metallic), the experiment reveals that matte black surfaces are the most effective at both emitting and absorbing infrared radiation. The shiny metallic surface, on the other hand, reflects infrared radiation. This engaging experiment highlights the difference in infrared properties of materials, offering valuable insights for students in understanding thermal radiation.

Takeaways

• 😀 Infrared radiation is emitted by hot surfaces, including glowing coals, which cannot be seen by the human eye.
• 😀 The Lesley's Cube is used to measure how much infrared radiation is emitted by different surfaces.
• 😀 The surfaces in the Lesley's Cube include shiny metallic, white, shiny black, and matte black.
• 😀 Infrared radiation emitted by the surfaces is measured using an infrared detector to ensure consistency and accuracy.
• 😀 Matte black surfaces emit the most infrared radiation, followed by shiny black, white, and shiny metallic surfaces.
• 😀 A thermometer with a blackened bulb can also be used to measure infrared radiation, though it has lower resolution than an infrared detector.
• 😀 The ability of a surface to absorb infrared radiation is tested by using an infrared heater and metal plates coated with different surface types.
• 😀 The time it takes for a drawn pin to fall off, attached by Vaseline, is used to determine how well a surface absorbs infrared radiation.
• 😀 Matte black surfaces absorb infrared radiation more effectively than shiny metallic surfaces.
• 😀 Shiny metallic surfaces reflect infrared radiation rather than absorbing or emitting it.
• 😀 This practical is crucial for understanding the behavior of infrared radiation and prepares students for related questions in exams and revision workbooks.

Q & A

What is the main purpose of the experiment in the video?

The main purpose is to investigate how much infrared radiation is absorbed or radiated by different surfaces.

Why is this experiment considered a required practical?

It is a required practical because it helps to understand the properties of infrared radiation, which is a key concept in physics.

What surfaces are used in the Lesley’s cube experiment?

The surfaces used are shiny metallic, white, shiny black, and matte black.

What does the Lesley’s cube help to measure?

The Lesley’s cube helps to measure the amount of infrared radiation emitted by different surfaces.

How is the infrared radiation measured in the Lesley’s cube experiment?

The infrared radiation is measured using an infrared detector, ensuring that the distance between the Lesley’s cube and the detector remains consistent for repeatable measurements.

Which surface emitted the most infrared radiation in the experiment?

The matte black surface emitted the most infrared radiation.

What equipment can be used if an infrared detector is not available?

If an infrared detector is not available, a thermometer with a blackened bulb can be used, though it has lower resolution than the infrared detector.

What does the resolution of a thermometer refer to in the context of this experiment?

The resolution refers to the smallest change in temperature that the thermometer can detect, which is less sensitive than an infrared detector.

How is infrared absorption measured in the second part of the experiment?

Infrared absorption is measured by using an infrared heater to heat two metal plates (one painted with shiny metallic paint and the other with matte black paint), and timing how long it takes for a drawn pin attached with Vaseline to fall off.

Which plate absorbs infrared radiation more effectively, the matte black or shiny metallic plate?

The matte black plate absorbs infrared radiation more effectively than the shiny metallic plate, causing the drawn pin to fall off first.