This page covers RRB NTPC Mirror & Water Images with complete concept notes, 11 graded practice MCQs, key points and exam-specific tips. Free to study.
Core ConceptRead this first — the foundation of the topic
CORE CONCEPT
Mirror Image: When you place a vertical mirror on the right side of an object, you get its mirror image. The image appears reversed horizontally
Water Image
When an object is reflected in water below it, you get its water image. The image appears flipped vertically
KEY RULES
Mirror Image Rules:
- Left becomes right, right becomes left
- Top and bottom positions remain same
- Curves change direction (C becomes reversed C)
- Numbers: 3 becomes reversed 3, 7 becomes reversed 7
Water Image Rules:
- Top becomes bottom, bottom becomes top
- Left and right positions remain same
- Curves flip vertically (smile becomes frown)
- Letters like M become W, p becomes d
Formula BlockMemorise — at least one formula appears in every paper
Exam PatternsWhat examiners ask — read before attempting PYQs
1
Find mirror image of letters/numbers/shapes
2
Find water image of clock faces
3
Combined mirror and water images
4
Which option matches the given transformation
ShortcutsUse these to save 30–60 seconds per question
#1 - CLOCK METHOD:
For clock mirror images:
- Mirror time = 12:00 - Given time
- If 3:15 is given, mirror = 12:00 - 3:15 = 8:45
- Remember to adjust minutes: 60 - given minutes
Worked ExampleSolve this step-by-step before moving on
1
Step 1
Write letters in reverse order: M-A-X-E
2
Step 2
Reverse each letter individually:
- E becomes reversed E
- X remains X (symmetrical)
- A becomes reversed A
- M becomes reversed M
3
Step 3
Final answer: Reversed M, Reversed A, X, Reversed E
WORKED EXAMPLE 2:
Question: Find water image of triangle with base at bottom
1
Step 1
Identify the orientation (base at bottom)
2
Step 2
Flip vertically - base moves to top
3
Step 3
All other features flip accordingly
4
Step 4
Answer: Triangle with base at top
SHORTCUT TRICK #2 - SYMMETRICAL LETTERS:
Symmetrical letters need no change:
- Horizontally symmetrical: A, H, I, M, O, T, U, V, W, X, Y
- Vertically symmetrical: B, C, D, H, I, O
- Use this to eliminate wrong options quickly
SHORTCUT TRICK #3 - DIRECTION ARROWS:
For arrows in mirror/water images:
- Mirror: Left arrow becomes right arrow
- Water: Up arrow becomes down arrow
- Combined: Diagonal arrows flip completely
Exam TrapsCommon mistakes students make — avoid these
#1:
Students confuse mirror and water images. Remember:
- Mirror = Side mirror of car (horizontal flip)
- Water = Lake reflection (vertical flip)
Many students apply wrong transformation and lose easy marks.
ADVANCED TIP:
For complex shapes, focus on one distinctive feature (like a small circle or line). Track how this feature moves in the transformation.
This saves time and reduces confusion.
PRACTICE STRATEGY:
Solve 10 questions daily. Start with simple letters, then move to numbers, shapes, and finally complex figures. Time yourself - aim for 30 seconds per question.
Key Points to Remember
Mirror image flips horizontally (left becomes right, right becomes left)
Water image flips vertically (top becomes bottom, bottom becomes top)
Clock mirror formula: 12:00 - Given time = Mirror time
Symmetrical letters remain unchanged in their respective transformations
Combined images require both horizontal and vertical flips
Direction arrows flip according to transformation type
Focus on distinctive features to track movement quickly
Letters like b become d in water image, p becomes q in mirror
Numbers 6 and 9 commonly interchange in water images
Practice identifying transformation type before attempting solution
Exam-Specific Tips
Mirror images show horizontal reversal with vertical positions unchanged
Water images show vertical reversal with horizontal positions unchanged
Clock showing 3:00 has mirror image showing 9:00
Letter 'R' becomes backwards 'R' in mirror image
Letter 'p' becomes 'q' in mirror and 'd' in water image
Number '2' becomes backwards '2' in mirror image
Triangle pointing up becomes triangle pointing down in water image
When a water image is formed, which of the following statements is TRUE?
A) The image appears upside down and reversed left-to-right
B) The image appears upside down only
C) The image appears reversed left-to-right only
D) The image appears identical to the original
Practice 2easy
A letter 'P' is written on a paper. When this paper is held in front of a mirror, the mirror image will look like which letter?
Practice 3easy
A word 'MIRROR' is written on a paper. When this paper is held in front of a mirror, how will the word appear?
Practice 4easy
When the figure shown below is reflected in a vertical mirror placed on its right side, which of the following will be the mirror image?
[Original: Triangle pointing RIGHT with a dot inside]
A) Triangle pointing LEFT with dot on same side
B) Triangle pointing LEFT with dot on opposite side
C) Triangle pointing RIGHT with dot on opposite side
D) Triangle pointing DOWN with dot inside
Practice 5medium
A word 'REASONING' is written on a piece of transparent paper. When this paper is placed in front of a mirror, how will the mirror image appear?
Practice 6medium
A figure consists of an arrow pointing to the upper-right (↗), a square, and a star. When viewed in a vertical mirror placed to the left of the figure, the arrow will point in which direction?
Practice 7medium
A figure shows a shape with a triangle pointing upward, a square below it, and a circle at the bottom. When this figure is reflected in a horizontal mirror (placed below the figure), which statement is correct?
Practice 8hard
A figure consists of an arrow pointing to the upper-right direction (45° angle from horizontal). When this arrow is first reflected in a horizontal mirror (water reflection), and then the resulting image is reflected in a vertical mirror, what will be the final direction of the arrow?
Practice 9hard
A figure shows a clock face with numbers 1-12. When viewed in a water reflection (vertical axis), the clock shows a time of 3:00. What was the original time on the clock before reflection?
Practice 10hard
A complex figure contains overlapping geometric shapes: a triangle, a square, and a circle. When this figure is placed in front of a mirror, the number of intersection points between shapes changes. If the original figure has 6 intersection points, how many intersection points will the mirror image have?
Practice 11hard
A word is written as 'REASONING'. When this word is placed in front of a mirror, what will be the mirror image? Then, if the mirror image is again placed in front of another mirror (perpendicular to the first), what will be the final image?
60-Second Revision — Mirror & Water Images
Remember: Mirror = horizontal flip, Water = vertical flip
Formula: Clock mirror time = 12:00 - given time
Trap: Don't confuse mirror and water transformations
Quick check: Identify symmetrical letters to save time
Focus: Track one distinctive feature for complex shapes
Speed tip: Eliminate options using symmetry rules
Common error: Applying wrong flip direction loses marks