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Light-time Example
Distance 1.5 x 10^8 km divided by speed 3.0 x 10^5 km/s is (1.53.0) x 10^(8-5) = 0.5 x 10^3. Rewrite 0.5 x 10^3 as 5 x 10^2, which is 500. So the time is 500 s. The same pattern works for any divide-then-adjust case.
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Light-time Example
What is it?
Distance 1.5 x 10^8 km divided by speed 3.0 x 10^5 km/s is (1.53.0) x 10^(8-5) = 0.5 x 10^3. Rewrite 0.5 x 10^3 as 5 x 10^2, which is 500. So the time is 500 s. The same pattern works for any divide-then-adjust case.
In simple words
- Distance 1.5 x 108 km divided by speed 3.0 x 105 km/s is (1.53.0) x 10(8-5) = 0.5 x 103.
- 1.5 x 10^8
- 3.0 x 10^5
- 500 s
Important terms
Light-Time Example: Distance 1.5 x 10^8 km divided by speed 3.0 x 10^5 km/s is (1.53.0) x 10^(8-5) = 0.5 x 10^3. Rewrite 0.5 x 10^3 as 5 x 10^2, which is 500. So the time is 500 s. The same pattern works for any divide-then-adjust case.
What you should learn
- Define and explain light-time example.
- Apply light-time example to a focused FBISE question.
- Check the answer for correct terms, evidence, working, and units.
Examples
- 1.5 x 10^8
- 3.0 x 10^5
- 500 s
CORE UNDERSTANDING
Distance 1.5 x 10^8 km divided by speed 3.0 x 10^5 km/s is (1.53.0) x 10^(8-5) = 0.5 x 10^3. Rewrite 0.5 x 10^3 as 5 x 10^2, which is 500. So the time is 500 s. The same pattern works for any divide-then-adjust case.
EXAM APPLICATION
State the correct term, connect it to the chapter rule or evidence, and use a clear example or calculation.
Recommended for Class 9
Full school-level explanation
Distance 1.5 x 10^8 km divided by speed 3.0 x 10^5 km/s is (1.53.0) x 10^(8-5) = 0.5 x 10^3. Rewrite 0.5 x 10^3 as 5 x 10^2, which is 500. So the time is 500 s. The same pattern works for any divide-then-adjust case.
Learn the idea, then use it:
WHAT — LIGHT-TIME EXAMPLE
Distance 1.5 x 10^8 km divided by speed 3.0 x 10^5 km/s is (1.53.0) x 10^(8-5) = 0.5 x 10^3. Rewrite 0.5 x 10^3 as 5 x 10^2, which is 500. So the time is 500 s. The same pattern works for any divide-then-adjust case.
HOW — Use the idea
Identify what is given, select this topic's rule or evidence, apply it one step at a time, and check the result.
CORE UNDERSTANDING
Distance 1.5 x 10^8 km divided by speed 3.0 x 10^5 km/s is (1.53.0) x 10^(8-5) = 0.5 x 10^3. Rewrite 0.5 x 10^3 as 5 x 10^2, which is 500. So the time is 500 s. The same pattern works for any divide-then-adjust case.
Remember
- 1.5 x 10^8
- 3.0 x 10^5
- 500 s
Examples
- 1.5 x 10^8
- 3.0 x 10^5
- 500 s
- LIGHT-TIME EXAMPLE: Distance 1.5 x 10^8 km divided by speed 3.0 x 10^5 km/s is (1.53.0) x 10(8-5) = 0.5 x 103. Rewrite 0.5 x 103 as 5 x
EXAM APPLICATION
State the correct term, connect it to the chapter rule or evidence, and use a clear example or calculation.
Remember
- correct term
- chapter link
- clear application
Examples
- Define first
- Show the rule or evidence
- Check units, labels, and conclusion
Remember
- 1.5 x 10^8
- 3.0 x 10^5
- 500 s
- keep the ideas separate
- 1.5 x 10^8
- 3.0 x 10^5
- 500 s
- correct term
Deeper understanding
Go beyond memorising Light-time Example. Connect the definition to reasons, relationships, exceptions, and exam wording.
Common mistakes
Exam focus
Core Idea
Key Points
Simple Check
How to Answer
Exam focus
Quick revision
- 1.5 x 10^8
- 3.0 x 10^5
- 500 s
- keep the ideas separate
- Light-Time Example: Distance 1.5 x 10^8 km divided by speed 3.0 x 10^5 km/s is (1.53.0) x 10(8-5) = 0.5 x 103. Rewrit
- WHAT — LIGHT-TIME EXAMPLE: Distance 1.5 x 10^8 km divided by speed 3.0 x 10^5 km/s is (1.53.0) x 10(8-5) = 0.5 x 103. Rewrit
Do not merge light-time example with a neighbouring idea that uses a different definition, rule, or method.
For long answers on Light-time Example: define clearly → explain the main parts → give one example → state one exam caution.
Exam Focus
Exam Focus
Important points
- 1.5 x 10^8
- 3.0 x 10^5
- 500 s
- keep the ideas separate
Important formulas
- 1.5 x 10^8
- 3.0 x 10^5
- 500 s
Common exam traps
- Do not merge light-time example with a neighbouring idea that uses a different definition, rule, or method.
- Do not invent a formula, fact, unit, or diagram label that the chapter does not support.
Long question structure
Definition → key parts → example → exam caution
Common Mistakes
Common Mistakes
- Mistake
Do not merge light-time example with a neighbouring idea that uses a different definition, rule, or method.
- Mistake
Do not invent a formula, fact, unit, or diagram label that the chapter does not support.
- Mistake
Do not merge light-time example with a neighbouring idea that uses a different definition, rule, or method.
Revision Zone
60-Second Revision
Quick cues from this topic — use them for last-minute revision.
1.5 x 10^8
3.0 x 10^5
500 s
keep the ideas separate
Distance 1.5 x 10^8 km divided by speed 3.0 x 10^5 km/s is (1.53.0) x 10^(8-5) = 0.5 x 10^3. Rewrite 0.5 x 10^3 as 5 x 10^2, which is 500. So the time is 500 s
- Definition
- Distance 1.5 x 10^8 km divided by speed 3.0 x 10^5 km/s is (1.53.0) x 10^(8-5) = 0.5 x 10^3. Rewrite 0.5 x 10^3 as 5 x 10^2, which is 500. So the time is 500 s
- Example
- 1.5 x 10^8
- Critical warning
- Do not merge light-time example with a neighbouring idea that uses a different definition, rule, or method.
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Exam Practice
Define
Q1. Define Light-time Example.
Explain
Q2. Explain: CORE UNDERSTANDING.
Example
Q3. Give one clear example of Light-time Example and say why it fits.
Mistake
Q4. State one common mistake students make about Light-time Example.
Exam note
Q5. Write a short exam note on Light-time Example: definition, two points, one example.
Sources & References
School-standard facts for Matric and Intermediate. Original explanations — not copied from textbooks.