The amount of heat required to change the state of 1 kg of a substance from solid to liquid at its melting point without any change in temperature is called: MCQ with Answer and Explanation

Explanation:
Polarized sunglasses use polarizing filters to block horizontally polarized glare reflected from surfaces (water, roads). LCD displays use liquid crystals to rotate polarization, controlling light transmission through polarizers. Memory tip: 'Polarization applications: glare reduction (sunglasses), display technology (LCDs), 3D movies'. This application question tests wave optics uses, frequently appearing in competitive exams. Always link physical principles to everyday technologies; competitive exams emphasize practical relevance of physics concepts, making abstract phenomena tangible through common devices.

Explanation:
Magnetic field lines represent direction of force on an isolated north pole. They emerge from north and enter south. They never cross. Tangent gives field direction. Compass aligns along these lines.

Explanation:
g=0 at centre, so weight zero.