5. (a) Which colour of visible light has the longest wavelength? A blue B green C red D yellow (b) Some television remote controls use infrared radiation and other remote controls use radio waves. Explain why an infrared remote control may not switch on the television from behind an armchair but a radio wave remote control always will. (c) Figure 4 is a diagram of a water wave. A cork is floating on the water. (i) Use the scale on the diagram to measure the wavelength of the wave. wavelength = ............................ cm (ii) Describe the motion of the cork. You should include how the cork moves relative to the direction of travel of the wave. (d) A different water wave has a wavelength of 0.25 m and a frequency of 1.5Hz. Calculate the wave speed. wave speed = ............................ m/s (Total for Question 5 = 9 marks)

GCSE Edexcel Physics Combined Science Waves: 5. (a) Which colour of visible l

5. (a) Which colour of visible light has the longest wavelength? A blue B green C red D yellow (b) Some television remote controls use infrared radiation and other remote controls use radio waves - Edexcel - GCSE Physics Combined Science - Question 5 - 2019 - Paper 1

Question 5

5. (a) Which colour of visible light has the longest wavelength? A blue B green C red D yellow (b) Some television remote controls use infrared radiatio... show full transcript

Worked Solution & Example Answer:5. (a) Which colour of visible light has the longest wavelength? A blue B green C red D yellow (b) Some television remote controls use infrared radiation and other remote controls use radio waves - Edexcel - GCSE Physics Combined Science - Question 5 - 2019 - Paper 1

Step 1

Which colour of visible light has the longest wavelength?

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Answer

The correct answer is C red, as red light has the longest wavelength in the visible spectrum.

Step 2

Explain why an infrared remote control may not switch on the television from behind an armchair but a radio wave remote control always will.

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Answer

Infrared radiation doesn't penetrate solid objects effectively. Therefore, if the remote control is behind an armchair, the emitted infrared rays are blocked, preventing the television from receiving the signal. In contrast, radio waves have a longer wavelength and can easily pass through obstacles, allowing a radio wave remote control to function even when obstructed.

Step 3

Use the scale on the diagram to measure the wavelength of the wave.

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Answer

To find the wavelength, measure the distance between two consecutive peaks. From the diagram, the wavelength is approximately 10 cm.

Step 4

Describe the motion of the cork. You should include how the cork moves relative to the direction of travel of the wave.

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Answer

The cork moves up and down in a vertical motion while the wave travels horizontally. This means the cork oscillates perpendicular to the direction of wave travel, floating on the surface of the water.

Step 5

Calculate the wave speed.

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Answer

Wave speed can be calculated using the formula: $ext{wave speed} = ext{wavelength} imes ext{frequency}$ Substituting the values, we have: $ext{wave speed} = 0.25 ext{ m} imes 1.5 ext{ Hz} = 0.375 ext{ m/s}$ Therefore, the wave speed is 0.375 m/s.

5. (a) Which colour of visible light has the longest wavelength? A blue B green C red D yellow (b) Some television remote controls use infrared radiation and other remote controls use radio waves - Edexcel - GCSE Physics Combined Science - Question 5 - 2019 - Paper 1

Which colour of visible light has the longest wavelength?

Explain why an infrared remote control may not switch on the television from behind an armchair but a radio wave remote control always will.

Use the scale on the diagram to measure the wavelength of the wave.

Describe the motion of the cork. You should include how the cork moves relative to the direction of travel of the wave.

Calculate the wave speed.

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