What is the magnifying power M of a simple microscope (magnifying glass) of focal length f when image is formed at near point D? (Hard)
Answer and explanation
Correct answer: D. 1 + D / f
- Step 1: Using the lens formula with image distance v = -D and object within focal length. Step 2. Magnification M = 1 - v / f = 1 - (-D) / f = 1 + D / f. Answer: 1 + D / f. Why not the others: D / f is the magnification when image is formed at infinity (relaxed eye); 1 - D / f has wrong sign; f / D inverts ratio.
Practise more Waves, Thermodynamics and Optics.
Free questions with an explanation for every one, and full timed Higher Secondary Certificate Examination (Bangladesh) mock tests.
More Waves, Thermodynamics and Optics questions
- What is the time period T of a simple pendulum of length L in a gravitational field g for small oscillations?
- If the length of a simple pendulum is increased by 4 times, what happens to its time period?
- What is the velocity v of a wave having frequency f and wavelength lambda?
- What is the frequency of beats produced when two sound waves of frequencies 256 Hz and 260 Hz interfere?
- In a standing wave, what is the distance between two consecutive nodes?
- What is the distance between a node and its adjacent antinode in a stationary wave?