Q1.9: NCERT Physics - Part 1 UNITS AND MEASUREMENT 1.9 Solution: The photograph of a house occupies an area of 1.75 cm_ on a 35…

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Q1.9: NCERT Physics - Part 1 UNITS AND MEASUREMENT 1.9 Solution: The photograph of a house occupies an area of 1.75 cm_ on a 35…

⚠️ Common Exam Traps & Conceptual Pitfalls

Students often divide the screen area by the slide area without first converting cm² to m², treating the numbers as directly comparable. Always express both areas in the same unit (e.g., convert $1.75\,\text{cm}^2$ to $1.75\times10^{-4}\,\text{m}^2$) before forming the area ratio, then take the square root to obtain linear magnification.

The photograph of a house occupies an area of 1.75 cm_ on a 35 mm slide. The slide is projected on to a screen, and the area of the house on the screen is 1.55 m_. What is the linear magnification of the projector-screen arrangement?