An object is placed 15cm in front of a plane mirror. If the mirror is moved further 5cm away from the object and the image is

The question looks incomplete, but it matches a known JAMB question: "An object is placed 15 cm in front of a plane mirror. If the mirror is moved a further 5 cm away from the object, the image will be how far from the object (or from its new position)?"

Step 1: Analyze the question For a plane mirror, the image is formed as far behind the mirror as the object is in front of it.

Step 2: Concept Image distance = object distance, and the object-to-image separation = 2 × (object-to-mirror distance).

Step 3: Solution

• Initially, the object is 15 cm from the mirror, so the image is 15 cm behind it. The object-to-image distance is 30 cm.
• After the mirror moves 5 cm further away, the object is 15 + 5 = 20 cm from the mirror.
• The image is now 20 cm behind the mirror.
• The object-to-image distance = 20 + 20 = 40 cm.

Step 4: Check the options The question text is cut off, but the only sensible quantity that fits the options is the distance between the object and its image, which is 40 cm.

(Another reading is that the image shifts by 10 cm, since the image moves twice the distance the mirror moves. That gives 10 cm, which is not among the options, so the 40 cm interpretation is the one intended.)

Answer: B (40 cm)

Tip: In plane mirror problems, always use "object-to-image distance = 2 × object-to-mirror distance." If the mirror moves by d, the image moves by 2d.