Mirror and Water Image
1. Mirror Image
When an object is placed in front of a mirror, the image formed is called a mirror image.
Rules:
- Left ↔ Right are interchanged.
- Top and Bottom remain the same.
- Image distance from the mirror = Object distance from the mirror.
- Image size = Object size.
Example: ROOPA → Mirror image → APOOR
2. Water Image
When an object is placed near still water, the image formed in the water is called a water image.
Rules:
- Left and Right remain the same.
- Top ↔ Bottom are interchanged.
- Image size = Object size.
- The image appears upside down.
Example:
12345 → Water Image → 54321 (Wrong for ordinary water-image concept)
The correct idea is that the vertical position changes, while left-right order remains unchanged:
12345
↓12345 (flipped top-to-bottom)
3. Key Difference
1. Mirror Image
- Left ↔ Right are interchanged.
- Top & Bottom remain the same.
- The image appears side-to-side reversed.
- Image size remains the same as the object.
- Example: ROOPA → APOOR
2. Water Image
- Left & Right remain the same.
- Top ↔ Bottom are interchanged.
- The image appears upside down.
- Image size remains the same as the object.
- Example: The object is reflected vertically in water.
Trick
- MIRROR → Left ↔ Right (Side change)
- WATER → Top ↔ Bottom (Up-Down change)
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Mirror & Water Image – PYQ MCQs
Q1. Which of the following represents the mirror image of ROOPA ?
A. APOOR B. ROOPA C. APORO D. OAPOR
Ans: A. APOOR
Explanation: In a mirror image, Left ↔ Right are interchanged. Therefore, ROOPA → APOOR.
Q2. In a mirror image, which of the following changes ?
A. Top and Bottom B. Left and Right C. Size only D. Shape only
Ans: B. Left and Right
Explanation: A mirror reverses the left and right sides, while the top and bottom remain unchanged.
Q3. In a water image, which of the following changes ?
A. Left and Right B. Size and Shape C. Top and Bottom D. Only the left side
Ans: C. Top and Bottom
Explanation: A water image is a vertical reflection. Hence, Top ↔ Bottom are interchanged, while left and right remain the same.
Q4. Which statement is correct about a mirror image ?
A. Top and bottom are interchanged B. Left and right are interchanged C. Image becomes upside down D. Image becomes smaller
Ans: B. Left and right are interchanged
Explanation: The main rule of a mirror image is Left ↔ Right. The size remains the same.
Q5. Which statement is correct about a water image ?
A. Left and right are interchanged B. Top and bottom remain the same C. Top and bottom are interchanged D. Image size becomes double
Ans: C. Top and bottom are interchanged
Explanation: In a water image, the object appears upside down, so Top ↔ Bottom.
Q6. The mirror image of 12345 will have:
A. Same left-to-right order B. Reversed left-to-right order C. Reversed top-to-bottom only D. No change
Ans: B. Reversed left-to-right order
Explanation: Mirror reflection changes the left-right position. Therefore, the sequence appears in reverse order.
Q7. The water image of an object is formed by changing its:
A. Left and right position B. Top and bottom position C. Size D. Colour
Ans: B. Top and bottom position
Explanation: Water reflection changes the vertical position, so Top ↔ Bottom.
Q8. If an object is placed 10 cm in front of a plane mirror, the image will be formed:
A. 5 cm behind the mirror B. 10 cm behind the mirror C. 15 cm behind the mirror D. 20 cm behind the mirror
Ans: B. 10 cm behind the mirror
Explanation: In a plane mirror: Object distance = Image distance
Therefore, image distance = 10 cm behind the mirror.
Q9. Which is the easiest trick to remember ?
A. Mirror → Top-Bottom B. Water → Left-Right C. Mirror → Left-Right; Water → Top-Bottom D. Both are the same
Ans: C. Mirror → Left-Right; Water → Top-Bottom
Explanation: i. Mirror → Left ↔ Right, ii. Water → Top ↔ Bottom
Q10. A water image of a vertically written word will appear:
A. Horizontally reversed B. Upside down C. Larger D. Smaller
Ans: B. Upside down
Explanation: Water reflection reverses the object vertically, making it appear upside down.