A film projector and microscope give equal magnification. But a film projector is not used to see living cells because
a microscope has greater resolving power than a projector.
The question asks why a film projector, despite having the same magnification as a microscope, is unsuitable for viewing living cells.
Magnification vs. Resolving Power
Magnification makes objects appear larger, while resolving power determines the ability to distinguish between two closely spaced points. Both are important for viewing small objects, but resolving power is critical for seeing detail.
Why Microscopes are Used for Cells
- Living cells contain tiny, intricate structures that are very close together.
- To see these structures clearly, an instrument needs high resolving power to separate these close points.
- A microscope is specifically designed with high resolving power to achieve this.
Film Projector Limitations
A film projector magnifies an existing image (from a film frame) to be viewed on a large screen. Its primary function is magnification for distant viewing, not the resolution of minute details inherent in the original image subject (like a cell).
Resolving Power Difference
The key difference lies in resolving power. Microscopes possess significantly higher resolving power compared to film projectors. While both might magnify equally, only the microscope can distinguish the fine details necessary to observe the structures within living cells.
Conclusion
Therefore, a film projector is not used to see living cells because a microscope has greater resolving power, enabling the visualization of the fine details essential for cell observation.
Important Questions from Optics and Diffraction
A monochromatic and linearly polarised light is used in a Young's double slit experiment. A linear polarizer, whose pass axis is at an angle $45^\circ$ to the polarization of the incident wave, is placed in front of one of the slits. If $I_{max}$ and $I_{min}$, respectively, denote the maximum and minimum intensities of the interference pattern on the screen, the visibility, defined as the ratio $\frac{I_{max} - I_{min}}{I_{max} + I_{min}}$ is
- The separation between the energy levels of a two-level atom is 2 eV. Suppose that $4 \times 10^{20}$ atoms are in the ground state and $7 \times 10^{20}$ atoms are pumped into the excited state just before lasing starts. How much energy will be released in a single laser pulse?
A screen has two slits, each of width $w$, with their centres at a distance $2w$ apart. It is illuminated by a monochromatic plane wave travelling along the $x$-axis.
The intensity of the interference pattern, measured on a distant screen, at an angle $\theta = n\lambda/w$ to the $x$-axis isA pair of parallel glass plates separated by a distance $d$ is illuminated by white light as shown in the figure below. Also shown is the graph of the intensity of the reflected light $I$ as a function of the wavelength $\lambda$ recorded by a spectrometer.
Assuming that the interference takes place only between light reflected by the bottom surface of the top plate and the top surface of bottom plate, the distance $d$ is closest to- A highly collimated laser beam with a diameter of 1 cm and wavelength 500 nm is directed from the earth's surface towards the moon (~384,000 km away from the earth). Assuming ideal diffraction limited propagation in vacuum, which of the following best estimates the diameter of the beam upon returning to the earth after reflection from an ideal reflector installed on the moon.
