Black Holes & Astronomy Basics

Albert Einstein first proposed that gravity affects light's motion through his General Theory of Relativity in 1915. His work predicted that massive objects like stars would bend light passing near them, which was later confirmed by Eddington's observations.

The event horizon is the boundary surrounding a black hole beyond which nothing can escape, not even light. It's the point of no return for any matter or radiation. Options B, C, and D are incorrect - the event horizon is not about reflection, refraction, or 'nothing happening'.

Gravitational lensing is the bending of light due to gravitational effects from massive objects, not just black holes. It occurs when a massive body curves spacetime, causing light to follow a curved path. Option B is correct - it's about gravity's effect on light. Options A, C, and D are incorrect as they mention magnetic fields or restrict it to black holes.

From the perspective of an observer on Earth, someone falling into a black hole appears to slow down as they approach the event horizon due to gravitational time dilation, and seems to take infinite time to cross it. This is called infinite redshift. Option B correctly describes this relativistic effect. Options A, C, and D are incorrect.

Nephrons are the functional units of the kidney responsible for filtering blood and producing urine. They are found exclusively in the kidneys.

One unit of electricity is defined as one kilowatt-hour (kWh), which means using 1 kilowatt (1000 watts) of power for 1 hour. This is the standard unit for billing residential electricity consumption worldwide.

Diesel engines use fuel injection and compression ignition, so they don't require carburetors. Carburetors mix air and fuel for spark-ignition engines like petrol engines, not diesel engines.