In its rest frame, a source emits light in a conical beam of half-angle width −45° to 45°. An observer is moving towards the source with a speed v. For the observer, the beam half-angle width appears to be −30° to 30°. The speed v of the observer is closest to:

Which Indian independence movement leader was primarily known for his philosophy and practice of non-violent civil disobedience?

Who gave the call for 'Do or Die' during the Quit India Movement in 1942?

Which of the following revolutionary pairs were imprisoned together in Cellular Jail and faced harsh conditions, contributing significantly to the Indian independence movement?