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IELTS Practice Reading: Note/Summary Completion Diagram ID: #56526 Hard Night vision technology
Instructions ›
Choose NO MORE THAN TWO WORDS from the passage for each answer.
1 Select text → 2 Right-click → 3 Highlight or Add Note

Night vision technology has transformed from old-fashioned bulky devices to compact sophisticated equipment that can intensify any light source up to 50,000 times. A device for night vision was first developed in the 1930s by the German military, and later by the Americans. Today, it has become an essential device in the kit of soldiers, permitting them to find out their targets in reduced visibility or complete darkness and move around in comparative safety as there are fewer chances of a surprise attack. ‘It improves their mobility, their survivability and their lethality’, says Lt. Col. Timothy Fuller.

Even on dark nights, the stars and the moon emit near-infrared light. In a device that works on image enhancement technique, this faint light is captured to amplify it to a visible level. As the light consisting of photons enters the front lens of the image intensifier tube, it hits a photocathode which converts the photons into electrons. These electrons multiply as they pass through a thin microchannel plate. At the end of the tube, the electrons strike a phosphor screen which converts them back into photons and creates an image, usually green, on the screen. Since more photons are emerging than those which entered the tube, the image is much brighter than the original scene. Rich Urich, director of operations at Night Vision Equipment Company in Prescott Valley Arizona, says, ‘The reason it is green is because when you put the unit down, you want your eyes to remain dilated so you can see in dim light.’ 

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Question Focus: Identifying the main tube/device shown in the diagram

Correct Answer: image intensifier

Why this is correct: The diagram labels the main tube that captures and enhances light. The passage clearly names this part as the image intensifier tube, so the answer must be image intensifier.

Passage Reference: In a device that works on image enhancement technique, this faint light is captured to amplify it to a visible level. As the light consisting of photons enters the front lens of the image intensifier tube

Common Mistake: Students may write night vision device because it sounds logical, but this phrase is too general and not the labelled part in the diagram. This is a context shift trap.

Paraphrasing: Passage: 'image intensifier tube' = Diagram: 'main tube that enhances light'

Tips: For diagrams, match each label to a physical part named in the passage, not a general idea.

Key Vocabulary:

  • intensifier = makes stronger
  • tube = long hollow container

Question Focus: Identifying the component that converts photons into electrons

Correct Answer: photocathode

Passage Reference: As the light consisting of photons enters the front lens of the image intensifier tube, it hits a photocathode which converts the photons into electrons.

Why this is correct: The diagram shows the first internal part the light hits. The passage says the light hits a photocathode, which converts the photons into electrons, so this matches exactly.

Common Mistake: Some students write front lens, but the lens only lets light in and does not convert photons. This is a partial truth trap.

Paraphrasing: Passage: 'photocathode converts photons' = Diagram: 'part that changes light into electrons'

Tips: Look for verbs like 'converts' or 'changes' in the passage to identify process steps.

Key Vocabulary:

  • photon = light particle
  • electron = tiny charged particle

Question Focus: Identifying the part where electrons multiply

Correct Answer: microchannel plate

Passage Reference: These electrons multiply as they pass through a thin microchannel plate.

Why this is correct: The diagram points to the middle section where the signal becomes stronger. The passage states that electrons multiply as they pass through the microchannel plate, so this is the correct label.

Common Mistake: Students may write image intensifier again, but that is the whole tube, not this specific part. This is a wrong section trap.

Paraphrasing: Passage: 'electrons multiply in the microchannel plate' = Diagram: 'section where electrons increase'

Tips: Follow the order of the process. Diagrams usually move step by step like the passage.

Key Vocabulary:

  • multiply = increase in number
  • microchannel = very small channel

Question Focus: Identifying the screen that turns electrons back into visible light

Correct Answer: phosphor screen

Passage Reference: At the end of the tube, the electrons strike a phosphor screen which converts them back into photons and creates an image, usually green, on the screen.

Why this is correct: The diagram shows the final part where the image appears. The passage says electrons strike a phosphor screen, which creates an image, so this directly matches.

Common Mistake: Some students write screen only, but this is incomplete and not the exact term from the passage. This is a partial truth trap.

Paraphrasing: Passage: 'phosphor screen creates an image' = Diagram: 'final screen showing the image'

Tips: Always copy the full technical term if it appears in the passage.

Key Vocabulary:

  • phosphor = light-producing material
  • image = picture

Question Focus: Identifying the colour of the image produced

Correct Answer: green

Passage Reference: creates an image, usually green, on the screen. Since more photons are emerging than those which entered the tube, the image is much brighter than the original scene. Rich Urich, director of operations at Night Vision Equipment Company in Prescott Valley Arizona, says, 'The reason it is green is because when you put the unit down, you want your eyes to remain dilated so you can see in dim light

Why this is correct: The diagram asks for the colour of the final image. The passage clearly states the image is usually green, so the answer is green.

Common Mistake: Students may write bright because the image is brighter, but that describes intensity, not colour. This is a paraphrase trap.

Paraphrasing: Passage: 'usually green' = Diagram: 'colour of the image'

Tips: For single-word gaps, be careful not to add extra descriptive words.

Key Vocabulary:

  • dilated = opened wider
  • dim = not bright

General Tips:

  • Diagram completion follows passage order. Find the first label, then move forward step by step.
  • Always copy the exact word from the passage. Do not change it or use a synonym.
  • Check the word limit carefully. More than two words is automatically wrong here.
  • Use process verbs like 'enters', 'hits', 'multiply', and 'creates' to track each stage.

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