Ray Optics and Optical Instruments: Class 12 Physics (CBSE) important questions and practice

Topics in this chapter

• Reflection by spherical mirrors and the mirror equation
• Refraction, total internal reflection and its applications (optical fibres)
• Refraction at spherical surfaces and by lenses; lens maker's formula; power and combination of lenses
• Refraction through a prism and the angle of minimum deviation
• Optical instruments: microscope (simple, compound) and telescope (refracting, reflecting) with magnifying power

What examiners usually ask

• Derive the lens maker's formula for a thin convex lens
• Draw a labelled ray diagram of a compound microscope and derive the expression for its magnifying power when the image is at the least distance of distinct vision
• A ray of light passes through an equilateral prism such that the angle of incidence equals the angle of emergence and each is 3/4 of the angle of the prism; find the angle of deviation

Exam tip

Ray diagrams for the compound microscope and astronomical telescope (normal adjustment) are asked almost every year with their magnification formulas; the lens maker's formula derivation and the prism relation n = sin((A + Dm)/2)/sin(A/2) are the other regular items.

Ray Optics and Optical Instruments on other boards and exams

• NEET UG Physics
• Bihar Board Class 12 Physics
• UP Board Class 12 Physics
• MP Board Class 12 Physics

Frequently asked questions