Ray Optics and Optical Instruments — Physics STD 12 Science — Question

Name the physical quantity which remains same for microwaves of wavelength 1mm and UV radiations of 1600 Å in vacuum.

Two blocks A and B of mass m_A and m_B respectively are kept in contact on a frictionless table. The experimenter pushes the block A from behind so that the blocks accelerate. If the block A exerts a force F on the block B, what is the force exerted by the experimenter on A?

Galileo was punished by the Church for teaching that the sun is stationary and the earth moves around it. His opponents held the view that the earth is stationary and the sun moves around it. If the absolute motion has no meaning, are the two, viewpoints not equally correct or equally wrong?

Write the formula for capacitance of parallel plate capacitor. What effect does the area of the plates have on capacitance?

Two Polaroids are placed with their optic axis perpendicular to each other. One of them is rotated through 45°, what is the intensity of light emerging from the second Polaroid if I₀ is the intensity of unpolarised light?

In an unbiased p-n junction, holes diffuse from the p-region to n-region because,

1. Free electrons in the n-region attract them.
2. They move across the junction by the potential difference.
3. Hole concentration in p-region is more as compared to n-region.
4. All the above.

Using figure find the relative luminosity of wavelength:

1. 480nm
2. 520nm
3. 580nm
4. 600nm

Water is slowly coming out from a vertical pipe. As the water descends after coming out, its area of cross-section reduces. Explain this on the basis of the equation of continuity.